Page last changed August 8, 2002

Spotlight on tyres

Preventing punctures

Is it worse on a Brompton?

• Chris Newport, Jul 1998:
  I'm still deeply in love with my L5 after 2 months of living together, but my view of the Raleigh Records with which it is shod [before March 2000] grows dimmer by the day.
  These wretched artefacts are averaging only 100 miles between punctures - I've had 3 so far. Is this typical or have I been particularly unfortunate? With my road bike, on which I do around 120 miles per week, I only expect one puncture every 3 months or so.
  It would be more bearable if it weren't so physically difficult to work with these tyres. The strength needed in your thumbs to get them back on the rims is more than most people possess.
  It might be entertaining for future folding bike rallies to supplement the standard 'fastest folding time' competition with a 'fastest time to fix a punctured Raleigh Record on the back wheel' competition.
  Is it reasonable to expect punctures at the same frequency as on a larger tyre?

Cause analysis

• Andrew Henry, Jul 2000:
  Rear tyres get a lot more punctures than front ones. To explain why, it helps to outline the different ways that you can get a puncture:
  1. The inner tube gets pinched. This happens if there is a heavy load on the wheel (rear wheels typically carry 60-65% of the weight on a bicycle) and if the tyre isn't pumped up hard enough.
     I found that I got punctures a lot less often once I bought a decent track pump, that has an accurate guage and can pump a tyre easily up to 100psi (7 atmospheres). When you have a nice pump, its quick and easy to pump up your tyres, so you do it more often, and with a good quality guage, you can tell when you have a slow puncture. This means that you can fix problems in the warm and dry and not by the roadside.
     The other time when inner tubes get pinched is if you snag them under the bead of the tyre when you repair a flat. The symptom for this is if you get a puncture a few miles after fixing another. For me, the solution to this problem was to watch whilst a mechanic fixed a puncture. Reading any number of descriptions in magazines and books didn't work for me.
  2. The tyre gets punctured by a thorn, nail, piece of glass etc. These happen more often in the wet as the rubber of the tyre cuts more easily. They also happen more often on the rear tyre. If you ride over a nail or thorn in the road, then it will probably be lying on its side. This isn't a problem for the front tyre, but every so often, the thorn gets plinged up as the front tyre passes over it, so that when the rear tyre comes along, the thorn is pointing straight up. Its worth scanning the road ahead carefully to try and avoid riding over debris.
     Tyres with a thick outer layer help for some punctures, if they stop a thorn from penetrating the casing. However a thinner and more supple tyre might have been able to survive the same thorn by flexing out of the way. The thinner tyre will also be lighter and roll much more smoothly.
  3. A patch comes loose on the inner tube. Its best to carry a spare inner tube with you and repair the punctured one when you get home. This gives the rubber solution longer to cure. It also means that you have a spare in case the inner tube is beyond repair (eg a puncture near the valve), and it means you don't have to mess about with instant patches.
  4. The tyre overheats when you brake heavily going down a hill. Sometimes its safer to ride down a hill quickly, so you lose more energy to air resistance than riding down slowly using the brakes. If you do this, the rim and tyre get hot and this can increase the chance of a puncture.
  I used to get a lot more punctures than I do now. Keeping tyres properly inflated, repairing them correctly, avoiding road debris and buying decent quality tyres is what I have done to help this.

Airless tyres (Greentyre): a scientific analysis

• Andrew Henry, Jul 2000:
  I found to my cost that , solid tyres are a good way of exchanging problems with punctures, with problems with buckled wheels. They also have a lot of rolling resistance, poor grip and poor ride. They are _extremely_ difficult to fit. Its easier and cheaper to learn how to use pneumatic tyres without getting punctures.
• John Blackburn, Nov 1998:
  The topic of puncture-resistant tyres has arisen again. Punctures can ruin the pleasure of cycling. Punctures jeopardise punctuality. Here is some new information.
  1. "Greentyre" is a well-known brand of polyurethane-foam tyre, but another company that makes similar tyres was the subject of an article in a recent issue of "Eureka", a UK magazine that specialises in engineering innovations and inventions. The company is Urathon Limited and is based in Wiltshire, UK. It recently became a subsidiary of American Tire Corporation of Akron, Ohio, USA. Urathon make tyres for wheelchairs, lawnmowers, golf buggies etc. They also make bicycle tyres but are aware of the drawbacks, which lead to higher rolling resistance.

     The article explains that, in a "freewheeling" test, cycles with polyurethane tyres come to a halt at about 60% of the distance reached with normal inflatable tyres. The reason is that hysteresis losses absorb energy. As a tyre rolls, the rubber (or plastic) in contact with the road is compressed. Energy is used when the rubber is compressed, and this energy comes from the cyclist's pedal-power. As the wheel rolls on, the rubber uncompresses, but only a part of the energy is recovered; most of the energy is lost as heat. A polyurethane foam tyre is worse than an air-filles rubber tyre in this respect. At the moment, the grade of polyurethane is a compromise; a grade is used which is satisfactory both for the surface of the tyre and the foam interior.

     To improve matters, Urathon are developing a two-shot moulding system. The surface is moulded from a thin hard-wearing grade of plastic, then filled with a foam than can contain more air than the grade previously used. Urathon claim that "freewheel" tests show that the improved tyre gives a figure of more than 90% (compared with the previous 60%), and further improvements may be possible.

     So, what is the ideal material to fill bicycle tyres with? We need something that is light (polyurethane tyres are currently slightly heavier than normal tyres), and easily balanced (current moulding techniques have difficulty in getting an even density of foam at all parts of the tyre, giving wheel-balancing problems). And it should be cheap.

     A very good substance is AIR. It is light, cheap, and naturally distributes itself evenly throughout the tyre. Best of all, it has very small hysteresis losses; when energy is used to deform an air-filled tyre, almost all of this energy is returned when the deformation is removed. Pumping the tyres to a very high pressure gives a limited improvement - the rubber is still there, it will still be compressed, and the losses will still occur.

     For best performance, you need a tyre that is mainly air and very little rubber, which is why very thin tyres are so effective in minimising the power required to propel a bicycle. When you hit a bump, the energy lost in the rubber is small if there isn't much rubber; the thickness and weight of rubber is more important than the tread pattern.

     This also applies to suspension systems. Imagine you are riding a bicycle at speed "v", and the total weight of cycle plus rider is "m". The kinetic energy stored in the moving bicycle is 0.5*m*v²

     Suppose you hit a bump so large that the bicycle bounces into the air, and moves upwards with speed "u". The upward energy is therefore 05*m*u². Where did the energy to throw the cycle in the air come from? >From the "forward" energy, which is now less than before; it is (0.5*m*v²)-(0.5*m*u²). The forward speed of the cycle had been reduced. Gravity dictates that the cycle will come down again, and hit the ground. Is the energy returned? Unfortunately it is not - much of it was lost on heating the tyre and (in the case of a sprung frame) compressing the high-hysteresis suspension medium. The cycle is now travelling more slowly than before the bump.

     So energy is lost on the way up and on the way down. It is necessary to have "damping" in a suspension system, with unavoidable energy loss, or the machine would bounce violently on contact with the ground.

     An ideal arrangement would be to use lossless air suspension, and absorb the energy in a storage device such as a large spring, whose energy could later be released to help you to climb hills or get away more quickly at traffic lights. But the weight of such a device would probably negate the improvements. In suspension systems, as with tyres, energy loss is minimised by improving the "air-to-rubber ratio". If a tennis ball were used as the suspension medium, it would lose less energy (because it is mainly air) than a solid block of polyurethane.

  2. There may be other approaches to the puncture-proof tyre. It occurred to me that a long steel coil spring could be used instead of an inner tube. The steel would have the highly elastic properties that go with low energy loss, it would be filled with air and the outer rubber tyre would give good road adhesion and silent running. The problem would be fitting and removal, and assuring that the tyre could not come off in use.
     Something like this has probably been tried. And abandoned. In 100 years of cycling, everything has been tried. But that's no reason to give up - this is 1998, new materials exist, better design methods, computers - it's time to try again.
     Such a "throw-away" puncture-proof wheel would suit the military. If it worked, everyone would want it, and after a few years the world would be piled high with useless worn-out tyres.
  3. The amount of energy needed to propel a bicycle seems to be about 100 watts. This is made up of:
     • Rolling resistance
     • Air resistance
     • Transmission losses
     A useful example: The Raleigh Electric Bicycle has a battery-pack containing 20 4 Ampere-Hour NiCad rechargeable cells (approx. D-size cells). Since one cell is 1.2 volts, the total voltage is 24 volts. The energy capacity (volts*ampere-hours) is therefore 24*4 = 96 Watt-hours. So it is about 100 watt-hours, which means that it will deliver a power of 100 watts for one hour. Raleigh claim that the cycle can be ridden for 15 miles at 15 miles per hour, so you can ride it for an hour. So the power needed is 100 watts. This is of course an approximate figure.

     As a comparison, the "Gossamer Condor" man-powered aeroplane that was pedalled 22 miles across the English Channel weighed a total of 104 kg and required 200 watts to maintain level flight. The pilot - a Californian racing cyclist - maintained this power for several hours.

     The problem for cyclists is hills, which require extra energy. It is very easy to calculate how much more: If a bicycle and rider of mass "m" is lifted upwards at a vertical speed "u", the power needed is m*g*u watts (where g=9.81 as always).

     Suppose you and your bike weigh 100 kg, and are riding along at 5 metres/sec (about 11 mph) and you come to a gradient of 1:20 (upwards). If you maintain your forward speed, then your upward speed "u" will be 5/20 = 0.25 metres/sec. The power is therefore 100*9.81*0.25 = 245 watts. This is in addition to the power needed to overcome rolling resistance etc.

     This is a lot of power. You can see that it is a pity, when descending a hill, to waste this power in the heating of brake-blocks. How much better to charge up a battery, or wind a spring.

     Recent postings have shown that transmission losses are very small compared with other losses, and in any case little can be done about them, apart from regular lubrication. Rolling resistance is about tyres and has been considered.

     So it is worth looking at air resistance. The resistance of a moving body is:

     R = k*rho*A*Cd*v² (where k is a constant).

     "rho" is the density of the air, about which we can do nothing, apart from avoiding valleys.

     A = the cross-sectional (frontal) area of the cyclist, as viewed from the front. Small people benefit here.

     Cd = the Coefficient of Drag. If a thin sheet of plywood is cut out to be the same shape as the cyclist plus cycle (as seen from the front), it would, by definition, have a Cd of 1. A useful improvement to both Cd and to "frontal area" can be made by adopting a more aerodynamic posture, such as using "full drop" handlebars.

     v² means the square of the speed. At double the speed, air resistance is bigger by (2²), which is 4 times bigger; at 3 times the speed it is 9 times bigger. If you ride much faster, this becomes very large indeed, and the energy loss in tyres and transmission become unimportant.

     How low a value of Cd can be achieved? Without plastic nose-cones and pointed tails, not much (but maybe these could also be used as luggage containers, with zips and ingenious folding handles). One might hope for values of around 0.3 using a recumbent design. Motor-cars manage this sort of figure. The best and most "slippery" shape is a long slim glider fuselage, which could have a Cd of 0.05 or less.

     The "square-law" speed calculation breaks down at very low speeds (by which I mean speeds much slower than those at which aircraft fly), but the accuracy is not too bad. At these low speeds, a correction factor called "Reynold's Number" has to be built into the calculation. Ask any cyclist what "Reynold's Number" is, and he will immediately reply "531". However, that is something completely different.

Summary of cures

• Rob Cope, Mar 1999:
  Don't touch Tuffy Tape: it may well score your tube & cause a puncture. It is too thick: even the more recent, softer varieties (unless NY version is much better than what reached UK). I use Protec, a much thinner polyurethane-based liner which seems effective: not cheap but has so far outlasted 3 tyres. Mike at Phoenix Cycles info@phoenix-folders.demon.co.uk had some a few months ago.
  Slime et al do work, but should be treated as temporary fixes (you will usually see some goo emerge when they start working: presumably why they tend to be dayglo colours). But they do get you home. The goo is slippy enough to stop a patch vulcanising so clean carefully before attempting repairs.
  Solid/semi-solid tubes: do not even think about them. See A to B 9 on Easiryda tubes.
  Boring old but still valid advice: keep tyre pressures up, check for cuts & embedded detritus, make sure brakeblocks & dynamo are adjusted OK & nothing is rubbing where it shouldn't. Avoid broken glass (you can usually recognise a UK cycle route by its alternative use as impromptu bottle-bank).

Tyre liners (Mr. Tuffy and allies)

• Jane Thomas:
  I use "Mr Tuffy", and I've found it to be excellent. On last inspecting my new primo tyres I found 3 cuts in the front tyre all containg glass, and a piece of glass inside the tyre between the tyre and the liner - so I guess thats at least 4 punctures I've avoided!
  One tip if you do decide to use this stuff - on prolonged use it can cut into the tube where the ends overlap causing a puncture! The way round this is to get a piece of old inner tube (2-3 inches should do) and put this between the end of the tuffy tape and your inner tube so that the tube is protected from the tuffy tape end.
• Custfold:
  A solution from an old hand seems to work - cut the sidewalls off the old Primo, or other light casing, and put it inside the new carcase.
• Rob Cope, Jul 1998:
  Puncture sealants work, but only really as a get you home service. Polyurethane tyre liners help but do nothing to protect sidewalls. Avoid the horrid Tuffy Tapes, which still damage inner tubes long term: mine came from Cyclecare long ago and apparently are Moulton-recommended (hence not cheap, but more or less indestructable). Even with this lot I still get the occasional blowout, but then local drinkers do tend to treat cyclepaths as impromptu bottlebanks.
• Ming Dinh, Jul 1998:
  The Tuffy strips are made of rubber, the kevlar ones are called Spinskins and both cut into the inner tubes, the Spinskins do so at a faster rate. I have only used Tuffy's and it can take from 1 1/2 to 3 years for them to puncture the inner tubes. I'm sure they also prevent some, but I'm not using them now, and haven't noticed getting bothered with flats much. Mind you, if I had to commute through broken glass a lot, I may put them on again.
• Doug Faunt, Jul 1998:
  I cut Tuffy tapes to fit my Brompton tires, and was unhappy with the smoothness of the cut, so I featherd the lap using a power sander. The parts stick togther tight enough so that I don't think there's wear at that point when I've looked. This problem could be minimized by rotating the tire with Tuffy a bit every now and then. Lastly, I'll gladly put in a new tube every year in order to prevent punctures at inconvenient times. I like Tuffies, and have them on my bikes.
• Jane Thomas, Jul 1998:
  I cut a piece of old inner tube, and use this to protect the inner tube proper from the ends of the tuffy tape. I renew this piece periodically, and it certainly gets cut into by the tuffy tape. I've had no problems with tuffy tape on my Brompton, and the only puncture I've had in recent years has been where the inner tube failed on its seam. Hurrah for tuffy tape.
  Having said all that, I had a disaster using a tuffy tape clone on my Moulton. Not only did it appreciably slow things down, but it actually abraided the inside of the tyres to such an extent that both tyres failed. I realised something was wrong as I was cycling home to a sort of 'thonkada thonkada' noise - on checking them I found that both tyres had bulges in the tread. When I got them off, they were full of grey dust, and the threads inside the tyres had been worn away in one place allowing the tyre to start bulging. Boo for 'tuffy' tape.
  'course I don't know if the problem was the Moulton or the 'tuffy' tape - and I'm not keen to repeat the experience, so no tape in the Moulton, and check the tyres twice a week.
• ?, Jul 1998:
  Has anyone mentioned in this discussion Panaracer 'Flataway' kevlar fabric tapes? These are not hard like Tuffy tape, are thin, lighter and easier to fit as they are self adhesive on one side which sticks to the inside of the tyre. As with all 'puncture proofing for pneumatic tyres, these are not puncture proof! It is worth saying though that when repairing the puncture I had a few weeks ago I found that the Flataway tape had prevented a number of minor punctures as the objects had discoloured the white tape where they had impinged on the fabric without piercing it.
  I bought my Flataway tapes from BikeFix in London for about £12-£13 each - more expensive than tuffy, but worthwhile I think. You could probably do three Brompton wheels with two rolls. I recently bought another Primo for the front after a short trial some time ago with one; I was most pleased to transfer the slightly grubby tape to the Primo as I ride around central London frequently and average 3-4 punctures per year.
• Ming Dinh, Jul 1998:
  Tuffys can cut along the sides as well as the ends of the strips, the resulting twin grooves around the whole length of the inner tubes makes them unpatchable.
• Rob Cope, Aug 1998:
  Have just come across Spin Skins on an American newsgroup. Sound like they may have solved some of the Tuffy Tape et al problems. Here's the website: http://www.spinskins.com/spinskins.nsf/ Before you get too excited, they're not cheap (c/$40 in US) and shortest size made is 20" (no they cannot be cut to length).
• Dave RM Lyons, Nov 1998:
  Having hear a number of contributions to the list about puncture prevention I feel compelled to de-lurk and raise the subject of Panaracer Flataway tapes. These are a kevlar felt like tape, self adhesive on one side which stick to the inside of the tyre. They do not prevent punctures 100% but give you more time to remove likely causes. As I remember they are about 12UKP each and you need one and a half for a Brompton - expensive but I think worthwhile. I use these tapes on both our Bromptons and the Birdy (which is undergoing the 16 inch rim (Custfold)/Primo/36 spoke treatment at Bikefix as I write). The tape is fairly soft and there is no risk of nipping/chafing the inner tube.
• Steven M. Scharf, Mar 1999:
  I've used Mr. Tuffy extensively on several bikes and have been almost flat free. The acid test was a tandem ride in Russia in 1993. I did get one flat in 700 or so miles, but it was due to a sidewall puncture IIRC. Compared to the other 15 or so tandems on the ride, I had far fewer flats.
  Most of the problems people are having are probably due to improper use.
• Custfold, Mar 1999:
  It is also the hard edges which perforate a neat circumferential line that is almost impossible to patch, on the tube.
• Channell Wasson, Sep 1999:
  Duct tape over the exposed overlapping joint along with talc helps save tube.
• Channell Wasson, Sep 1999:
  I bought expensive kevlar linings. After a one year use in Primo tires I finally had a flat. It appeared that the kevlar had cut the tube. The entire kevlar liner was broken like glass at about 1 inch intervals, and each exposed area was working hard to cut the tube. The tube was abandoned and Tuffy type tire liner was reinstalled with duct tape over end joint. cw
• Jane Thomas, Sep 1999:
  As a seasoned user of Tuffy tape, I've never had it cause a puncture - I cut it to fit, then place a piece of old inner tube between the overlapped cut end and the inner tube proper. I find that everything sticks gently together preventing any movement between the parts. The last puncture I had on my Brompton was caused by the join in the inner tube failing.
• Rob Cope, Oct 1999:
  Protec polyurethane liners: thinner than Mr T's. Were distributed by Wolber & recommended by Moulton. Does not in my experience reduce lifetime of inner tube.
  I *think* CycleCare & Pheonix Cycles (info@phoenix-folders.demon.co.uk) in London still have stock. Is/was supplied in 2 rolls sufficient for 2 700c wheels. Trimmed to Brompton size, leaves plenty spare but not quite enough for a 3rd 16" wheel, which is annoying: probably sufficient for you friend's Bickerton front wheel though. Instructions say to fix to inside of tyre with rubber solution, but this isn't really necessary.
  Pricier than Mr T but near indestructible. Won't stop sidewall punctures but neither will any liner.

Slime

• Pamela Barnett:
  I happen to live in an area that has a huge amount of thorn - producing weeds which are death on my tires. For two years, I dealt with multiple flats per season, and fear of going further than 2 miles from home. After realizing that my bike mechanic was getting rich off of me, I went to another fellow who guaranteed my tires for a year by doing the following:
  1. heavy duty inner tubes
  2. new, wider, heavier rim strip (the one given with the bike shifts and is cheap)
  3. fill the inner tubes with 'Slime' (trade mark). Slime is a polymer that is merely squirted into the tube BEFORE inflating it via the valve. It coats the inside of the tube and is a self sealing agent when punctures occur.
  I ride 10 miles daily, and have had no problems. My only regret was not to have replaced the so so tires provided with high pressure tires.
• David Cox:
  I've put "Slime" a coagulant fluid in both tubes and this does cut down punctures by sealing smaller holes from glass and thorns. Of 12 punctures since Feb94 (c8,000miles) the sealant has worked for 5 and got me home for one other. No good for traumatic splits, lumps of metal or impacts though !
• Johan Hesse, Jul 1998:
  I own among other bicycles a brompton. On the others i use special puncture resistant tyres.. they have a PVC breaker layer... But those are not available for a brompton. You could use SLIME TIRE SEALANT i use it on my coaching bicle i use for coaching rowing.. I bought it at Halfords in the netherlands. It will instantly seal most tread area punctures up to 1/8" in tube tires and 3/16" in tubeless..
  Its green slimy stuff you put into your tyres... it works very well...and costs almost nothing [14 guilders = +/- 4 pounds] for 2,50 ml which is enough for 2 tyres..
• Rob Cope, Jul 1998:
  Yes, it works most of the time ie still subject to Murphy's law. You unscrew the valve core, squeeze the gunk in (with care: it's luminous & stains!), put back the core, reflate the tyre and ride around a bit to distribute the stuff evenly. It doesn't block the valve (too big a hole. BUT it only repairs rather than prevents punctures. You will eventually get one that overwhelms it: when you then take the tube out, you will likely find a number of smaller holes that have been filled without fuss.
  Sorry, there is no 100% solution bar solid tyres (yuk). Aint life tough?
• Mark Maier, Jul 1998:
  Just a few questions. I understand this Slime stuff will seal any hole up to a certain size - what about the valve (this has probably been asked before)? E.g. if I decide to change from Records to Primos I will have to release the air in order to remove the Records. Will Slime not seal my valve, too? After Slime sealed a puncture, will the tube be glued to the tyre?
  If it really works that well, you will find me walking into Halfords, soon... - BTW, do you actually mean 2.5 ml (is this a decimal comma)? Or may I assume it's 250 ml and the comma just slipped in by accident...
• David Edge, Jul 1998:
  I fitted two Specialized pre-filled presta-valved tubes to a cumbersome cycle. The first punctured after 20 miles and spewed all gunk through a small hole. The second went 120 miles and sealed a puncture. Unfortunately, I didn't notice and when I hit the next pothole wrote off the rim due to low pressure. This was mildly irritating as I was off touring Germany the next day and had an essay to write. Janette learned wheelbuilding rather quickly that night.
  So GBP20 for the tubes, GBP20 for a new rim buys 120 miles of puncture free cycling (apart from two punctures). I'm not convinced.
  Since then, I've discovered Continental Top Tourings for the cumbersome and they puncture once a year at most (say 2000 miles with 120kg rider). I see they are now available in 20", but fear that even if they were available in 16" that their relative sluggishness would be exaggerated by the small wheel size.
• Steven Cain, Jul 1998:
  [...] Some months later I got CY [ Curious Yellow an L3]serviced. Freewheel Pimlico were advertising a superior alternative to Slime. Essentially liquid Teflon, that sits in your inner tubes, and heals all but the worst punctures as they happen. The catch is that you can't really DIY- a shop has to remove the cores of the inner tube valves and pump the stuff in. It was something like 5UKP each.
  Since then I've had no punctures. How significant this is difficult to tell, as I've done less than 300 miles on CY since (they're mending the escalators at Walthamstow and Victoria, which makes it all rather inconvenient).
  I've not seen the sealant advertised recently mind, which is a bit worrying. Rather ominously, Trek have started selling inner tubes with sealant included, but I worry that they'll only cover the 26in and 700c sizes; this could easily be enough to make the Freewheel service uneconomic.
• Roland Elsenberg, Mar 1999:
  I use Slime Tire Sealant. It helps against small punctures. Today it sealed a puncture caused by a small piece of glass. Last Tuesday it failed to seal a larger hole cut by a standing broken bottle. Half of the slime got out. When this happens, the tire must be cleaned properly. Otherwise the rubber plugs won't hold. Statistically Slime helps once in a month. It fails less than once in a year.
• Bob Gelman, Mar 1999:
  By "rubber plugs" I think you mean what in English is called a "patch". It has been my experience that if the hole is big enough so that the slime won't work (and that's most anything bigger than a thorn), the gooey mess gets all over the outside of the tube where the puncture is. It makes using a "patch" very difficult because the darn slime just keeps on coming out. The patch won't adhere to where the slime is on the tube. It makes a field repair very difficult. Also, slime weighs quite a bit.... After getting a golf tee (yes, golf tee!) stuck in my rear tyre and attempting half a dozen repairs in the field, I gave up on this stuff. I carry a tube. I also carry a conventional repair kit with a tube of rubber cement. I try to avoid using the cement because once you open it the next time you need it it will invariably be dried out; no matter how tight you close it. I try to make my repairs at home. I have found that a large jar of Elmers Rubber Cement (comes with a brush!) only costs $2, won't dry out, and will last for years. There used to be a product (from Germany?? England?) which were very small red gelatine like capsules with glue for individual use-once repairs. They were cheap and worked great. I haven't seen them for years and years....
• Rob Cope, Oct 1999:
  Puncture sealant goo (various colours & brands) will usually help you get you home, but gets all over tube making patching a pain. Not to be treated as a permanent repair: tends to give up loudly (flatulent raspberry that no one believes is from the bike), spectacularly (fluorescent goo flying everywhere like spray string) and (of course!) very publicly...

Airless tyres

• Roland Elsenberg, Jul 1998:
  Are there solid polyurethane tyres in Brompton-Land ? Greentyre seem to have all sizes including old-fashioned 28'', but they won't supply 37*349. Perhaps they don't dare, as the average Bromptoner is keen on speed and rolling-resistance. I am, too, on my red Brompton with Primos. On the black one I would like to try solid polyurethane if I could find some. If there are others tired of boarding a train or entering office with aluminium-powder on their fingers, perhaps we could convince Greentyre to stop neglecting us.
• Channell Wasson, Jul 1998:
  Roland, You can make your own. Iserts are often sold in bike sections of discount type stores. cut one to proper length plus a bit more, glue it together (super glue gel works), and put it in your 37 349 Brompton tire. It will be hard as H to get on, but you won't have to worry about pinching the tube. I would keep a spare set of wheels for nuematics. Solids give an awful ride so far as my experiments go, and yu will soon be tempted to change off the solids. cw
• Dave H, Jul 1998:
  ISTR a thing like pipe insulation which is cutto length and put into wheelchair tyres, and no doubt it can be put in any size (increasing the rotating mass & thus seriously depleting the acceleration/weight benefits.
  Solid tyrea also knock 6 bells out of the wheels and this is amplified by having short spokes.
• Mike Sparks, Jul 1998:
  What we use in our folding ATBs for military use are No More Flats solid foam inner tubes which NEVER GO FLAT. They are available from Cycle Manufacturing in Colorado. http://www.geocities.com/Pentagon/5265/atb.htm No more flats:

  Cyclo-Manufacturing 1438 S. Cherokee St Denver, CO 80223 (303) 744-8043

• Dave H, Jul 1998:
  The performance of a small wheeled bike is much more critically affected by the tyre and wheel performance - solid tyres are very hard on spokes (which are stressed more on SWB's) and the rotating mass is much more significant - hence the efect experienced when Primo tyres which weigh 2/3 of the weight of OEM Records, and light tubes (as little as half the weight with the 19-349 tube) are substituted - less punctures more weight - Mr Rubin wouldn't achieve his featherlight folder with such devices. (or was it fetherlight as in LRC)
• Roland Elsenberg, Aug 1998:
  Let's force them to make some for us! Another interesting system is the tubeless continental tire: http://www.conti.de/2wheel/tech/tube_e.htm . It requires a special rim. This rim is made by Rigida Tire and rim are only availiable in dino-size.
• Stephen W. Butler, Oct 1998:
  I have contacted the "No-More Flats" Company and discovered they do not market a tube that fits Brompton (16 x 1 3/8). I intend to try out their tubes on my full size mountain bike but have not yet ordered them. I hope it works out because I find the "gooey glop" in the tubes solution offends my sensibilities.
• David Edge, Nov 1998:
  The e-mail address of the supplier whose product was tested by A2B:
  eaziryda@inter-group.co.uk
• Ka Lun Tam, Mar 2000:
  You might also want to try Air Free Tires at http://www.airfreetires.com which happens to have 16" tires on their website. They're labelled as Child Safety Tire, but I suppose they might fit the bill.

Tyre pressure

• Phil Neff, Oct 1999:
  I also have had good luck with regard to flats. I think that inflating the tire to 80 psi helps. On all my bikes, now in my old age, I try to inflate to whatever is the maximum. On my street bikes it is 110 psi. I'm not sure why this might be, but my theory is that bits of glass and stickers that might puncture the tire never get the chance to adhere to the surface. Or it could be that there is less surface contacting the pavement, hence less chance of touching the bad things. At any rate, I get far fewer punctures now than when I used to be more careless about inflation pressure. A good floor pump with a pressure guage helps. I use it before most rides.

Time

• Stein Somers, Jul 1997:
  My second T5 seemed more puncture resistant than my first. I was told it had been a demonstration model in a store for a few months. Raleighs might become stiffer or less sticky (with respect to glass) over time, apparently a truth or myth cycling in bicycle world.

Insanity

Dear Spinskins,
I use a Birdy folding bike which has 18" x 1.5" (80 lb psi) tires made specially for this bike. Is there any way I could use your product on this unusual size tire?

<Spinskins> That's no problem. We do have to give you a special size but we can work that out. Just call our toll-free hotline at 1-888-477-4675 and ask for John. He can make the arrangements for you.

The plant is called puncture vine (tribulus terrestris) and it grows primarily on barren ground, ground that has either been sprayed with herbicides or is otherwise bare in arid regions. It does not compete with grasses or other roadside vegetation so it is easy to see. Know thy enemy and I think the major problem of flats will be solved. You can see this plant at: http://www.fortnet.org/CWMA/puncture.htm and http://chili.rt66.com/hrbmoore/Images/T-Z/Tribulus_terrestrus.jpg and http://gnv.ifas.ufl.edu/~fairsweb/images/lh/lhp58.gif

Jobst Brandt

Alternative valves

• Peter Amey:
  The most recent Folder magazine [Issue Twenty page 31] mentions "short" shraeder valve inserts which are supposed to help with this pressure loss on pump removal
• Ken Twydell:
  Another trick that I have found helpful is to use plumbers PTFE thread tape on the valve and hose threads. This eliminates all air loss so that really high pressures can be obtained. There still remains the unscrewing problem - I think that the short shraeder inserts would be a good idea.
• Malcolm Lyon:
  I read that item bought and some of the short valves but I find they still let quite a bit of air escape as I release them from my trackpump. I did see another item in an earlier issue of the Folder about chopping a bit off one of the long valves as a cure for the problem but I can't find the article. Has anyone tried that fix?

Fat or slim tyres?

1. they absorb more road shock,
2. they are much less susceptible to flats,
3. they have greater stability in rock and gravel,
4. they are easier to balance on in near stop condition,
5. they have less sink in sand and/or soft mud,
6. for any given distance of travel, they afford slightly more exercise,
7. they have better start/stop traction on ice or other slick surface.

• Mike Hessey, Sep 1998:
  Reduction of rolling resistance is desirable to reduce effort - speed does not come into it for the MANY riders who prefer tyres such as the Primo. Actually many youthful riders nowadays go for fat tyres because they look aggressive (to use your word), and are not interested in efficiency (probably because they don't do much cycling anyway). One could go on to question all the argument you quote, but I'm sure other knowledgable people on this list are going to do so! Interesting address you have - this combined with topic 6 leads me to guess that you are just amusing yourself trying to wind us all up - I hope that is the real explanation.
• Rob Cope, Sep 1998:
  [1] Tests show resistance to flats is more to do with the strength of the carcass than the thickness of the rubber on top (eg in the new issue of Bycycle which flopped onto my doormat this week). Also, deep treads can hold shards that smoother tyres shed, allowing the shard to penetrate deeper on later revolutions. I think this explains my experience of Primos vs Records. The Primos develop alarming numbers of small cuts & holes in the tread, but do not puncture much. The Records puncture more, usually from a lump of glass that has pressed deep into the tread.
  [5] Primos on Porthmadog beach 1997 (fitted to both a Brompton & a rewheeled Birdy) seemed to perform about as well as the low-pressure knobblies fitted to a standard Birdy.
  [7] In theory, surely, a slick tyre works best on slick surfaces? I remember coming a cropper on Morcambe jetty going over a marble/glass inlaid design with Records. Tried this again with Primos, no problem. But i think snow/ice is one of those (few) times I'd leave the Brompton at home & use something with bigger wheels.

Alternative tyres

Schwalbe

• Channell Wasson, Mar 2000:
  We have had two reports of tread separation failure on the new Schwalbe tire. This means the tread rubber has broken or separated away from the woven casing. The supplier will replace tires in event of such faillures. One of our customers was using the tire in light casual use.
• Scoman, Jul 2000:
  I'm at 1200 mi on my first set of schwalbs w/ 1 flat on the rear. Better than the Raleighs and far better than the Primos over similar mileage. Rear looks like it has a way to go before replacement is necessary.
• Roland Elsenberg, Jul 2000:
  My Schwalbe achieved 5000 km on the rear wheel. There is still some tread visible. It got 4 punctures on this distance, which is far better then the Primos or Raleighs I rode before.
• Mike Hessey, Jul 2000:
  My Schwalbes have performed superbly. I have had them fitted since late last year, and they have done around 900Km. Grip is good, and there is almost no sign of wear. I had my first puncture (rear of course) on Saturday, caused by a small piece of wire. I find the rolling resistance is very nearly as good as the Primos, and they are now my preferred tyre in this size. I haven't yet fitted the new Brompton tyre to try it, though I have a set ready.
• Chris Newport, Jul 2000:
  [...] the Schwalbes I put on around 3 months ago are excellent. After nearly 1000 miles there is little sign of tread wear, even on the rear.
  There *is* a bit more rolling resistance compared with the Primo or even the Record, but not enough to worry about and the advantage of being able to cycle on just about any surface without worrying about punctures (none so far, at least) outweighs just about everything else for me.
• Stein Somers, Jul 2000:
  It's quite rainy over here at the moment. I'm not happy with that and my Nordlicht dynamo is not happy with the new Schwalbe tyre. I have to force it with my heel for the first few minutes. Then it obeys without further hassle. So it's better than with my last Primo that kept on slipping, but worse than the first Primo that ran perfectly (until the tyres thread succumbed to the dynamo wheel).
• mark james, Aug 2000:
  [...] in 500 miles riding, 75 Kg on road, no rough stuff silliness ;-) 4 punctures/ one tyre (schwalbe). Failure - bad fortune??
• Martin Whitfield, Mar 2000:
  It may or may not be of interest but we have just completed surveying our latest map (of Bradford, England) using Schwalbe Marathons instead of Raleigh Records.
  Normally, such survey work (500 miles of riding on urban streets with glass-strewn cycle paths and rough lanes) would produce an average of four punctures. This has happened on every one of the past 12 maps we have done. Raleigh Records or Primos would produce the same result, although Records could be used with the dynamo.
  This time: no punctures.
  The tyres were pumped up near 100 psi and give good rolling resistance. They will be on the bike for the next map survey (end of March/beginning of April) and I will keep you informed of any incidents. This time it will be Rotherham...
• Chris Newport, Aug 2000:
  I now have Schwalbes front and back. Good roadholding, excellent puncture resistance (until they wear through), but VERY SHORT TREAD LIFE - and I see someone has reported the same experience in the latest A to B magazine.
  To be fair I've only gone through 1 Schwalbe so far, and I didn't measure its life accurately, but subjectively I reckon it must be well under half the life of a Record. Still, they're not that expensive and for me the absence of punctures compared to Records or Primos outweighs reduced lifespan.
• Martin Whitfield, Aug 2000:
  The ones talked about [in the "Map of London" item in A to B (Where can I find out more? - A to B)] are fitted to my bike and the rear has gone to a replaceable level in about 1,000 miles of (albeit hard) riding. The front is still OK.
  In that time I have had five punctures (the three in on day reported in A-B, all glass fragments on rainy day), one pressure puncture front wheel falling down one of London's deep potholes, and one glass somewhere else (Rotherham, I think).
  Although this may sound like a lot of punctures, I reckon it is about half that of the Records doing a similar amount of inner-city cycling. In my opinion, the Schwalbe has less rolling resistance at high pressures, but is quite hard on the wrists as a result.
• Chris Newport, Aug 2000:
  That lifespan roughly equates with my experience. I reckon I've done a little over a thousand miles on the Schwalbes (on relatively good roads though - Kew to the City and back). The front one is fine of course; it's the rear that gave up. But in fairness to Herr Schwalbe I weigh nearly 200 lbs so the rear wheel on my Brompton is heavily loaded - I had to have it rebuilt to stop the spokes breaking.
  The good news is that I had no punctures in either tyre until I had to replace the rear. I too thought I was a tread separation victim until I looked more closely and saw the cover grinning through the tread in places.
  I reckon a rear tyre on my MTB typically lasts 4000-5000 miles (though usually the tyre wall breaks down before the tread wears through). I've forgotten how to do the trig to calculate the effective length of a 16" tyre compared to a 26" tyre, but I would guess it's in the region of between 2:1 and 3:1. And given that on an MTB the weight is more evenly distributed between front and back wheels, perhaps the equivalent lifespan isn't so bad after all.
• Roland Elsenberg, Aug 2000:
  I still ride pre-production samples. In more than one year they did over 6000 km. Even on the rear wheel tread is visible. I had 6 punctures on the rear wheel, less than half compared to Records and nothing compared to Primos

How do the Schwalbe tires fit on the rim?

• Nico J. de Boer, Jul 2000:
  Much easier than the Raleighs!
• mark james, Jul 2000:
  Absolutely no bother at all as easy as Primos kms better than Records. Still I make sure bead is in middle of rim.

Brompton Mk3 tyre

• Mike, Jul 2000:
  The day after a Brompton was fitted to my rear wheel, I nearly came off it because it slipped from under me on a bit of a bend.
• Mike, Aug 2000:
  Slippery in wet on certain surfaces compared with Records.

Riding feeling

• Channell Wasson:
  I have run the Primo tires for hundreds of miles at 110 to 115 psi and find them comfortable and very durable. If the Raleigh Record (standard Brompton tire) is run at over 85 psi it is possible to blow out the tire sidewall. [...] Thread spacing in the Primo is much denser and therefore stronger. The Kenda tire blows at lower pressures. I would advise avoiding use of the Kenda gum wall 16" x 1 3/8" tire. It is no longer offered on the market, but they are still around.
• Andrew Henry:
  I found that these were wider than the Raleigh Record tyres and they are quite a close fit for the rear wheel. I had to bend the mudguard away using a pair of pliers. The tyre also runs quite close to one of the chainstays. Have I fitted the axle incorrectly or is this normal. I have an L5 Brompton from late 1995.
• Norman Tulloch:
  Certainly on perfect road surfaces the Primos are fine but on rougher roads they provide a ride which is, I think, harsher and more uncomfortable than the standard tyres run at 70 p.s.i. [...] They do seem to be of quite a light construction and I have already had to discard one because of a cut in the side wall.
• Rob Cope, Nov 1998:
  One distinct advantage of Primos not previously mentioned is they are much easier to remove & refit, even for the temporarily single-thumbed (fell on the other one). Hence it is feasible to mend simple punctures without removing the wheel (though make sure you do it better than I evidentially did).
• Scheiner, Joerg, Dec 1999:
  I had the chance to test my Schwalbe Marathon tyres on the weekend. When I mounted them last week I had difficulties with a small hole in the inner tube. Most probably I produced it during demounting of the primo tyre. This is fixed now and the tyres have been used for about 80 km. Rolling resistance seems to be a little bit higher than the primos. Grip is good on every surface. Although I pumped them up to the maximum of 7 bar (100 psi) they are not less comfortable than the primos in contrary I often found myself checking the pressure because the felt so soft during riding. I had a hard time on Sunday morning with frozen snow/ice on the roads. The tires didn't slip but the rolling resistance was quite high. I did not have another bike to compare to but think it would have been the same with any other tyre.
  So far I am quite satisfied.
• Mike Hessey, Dec 1999:
  My Schwalbes have now done a rather meagre 18 miles, but I am pleased with the performance so far. It's been a windy day, and this plus the fact that the tyres are on my old T5 and I rode last week on my SP (with Primos) make it difficult to judge performance accurately. I would say that rolling resistance didn't feel greatly different from the Primos, though the difference would be in the Primos favour. They gripped well, on the wet roads, though I didn't actually try to see at what point they would break away - I don't like coming off! I am running them at 90psi, and I too was surprised how comfortable they felt even at this pressure. The tyres are quite silent running (unlike the new Birdy tyres) which is a good sign for rolling resistance.
• Peter Amey, Dec 1999:
  This confirms my early impressions. All I can add is that the dynamo track seems to work well (with my B&M S6). The dyno runs very quietly and doesn't seem to slip - I did bash through a few puddles this morning to see.

Do slicks slip?

• Anthony Cartmell, Dec 1997:
  The leaves probably mostly slip on each other, and tyre choice might not make much difference unless you get studded tyres or extremely knobbly MTB-style ones.
  If you're trying to ride on ice, no amount of tread will help - you'll come off! (unless you ride a trike, in which case you will just go straight on!).
  You might find that slick tyres, with their larger contact area, are better than treaded tyres on frosted smooth surfaces. The tread will only help if it has something rough or soft to bite on to.
  As an experiment, just change the front tyre. It would be interesting to hear if you find it any grippier. Losing control of the front wheel is usually much more serious than the back, and when pedalling you usually get some warning slips on the back before it all gets too slippery.
• Len Rubin, Oct 1998:
  Primos do have a light tread. Not exactly a snow tire, but not a slick, either.
• Rob Cope, Oct 1998:
  Primos have a very light tread which wears smooth quickly, however this has not in my experience affected performance at all on any surface. I have yet to try them on ice, but on other smooth surfaces they out-perform Records in wet & dry conditions. One testbed was the marble-inlaid compass on one of Morecambe's jetties. On the Records, I skidded; on Primos, no problem.
  Winter riding is often on roads wet from a thaw: another situation where Primos will comfortably win. The Record has a reassuringly chunky tread, but this rarely has other than cosmetic effect (plus it tends to pick up grit of just the right size to puncture further down the road). Presumably the tread pattern means it is laying *less* rubber on the road than its slicker rival? Moreover, the compound used for the Primo tread is about 30 years younger than for the Record and the difference shows.
  The only time I have found Records surpassing Primos was an extremely churned-up canal path just after a rainstorm. Neither tyre performed particularly well but the Record tread did just about win out. By this time we had chosen to dismount & walk anyway!
• Roland Elsenberg, Oct 1998:
  I agree with Rob that they perform better than Raleighs due to their material. When I rode into our underground-parking (painted concrete, watered by cars) with my old Brompton, which is still on Raleighs after months of purely riding Primos I slipped and fell. No damage, but lesson learned.
• Willi Mindak, Oct 98:
  I have not tried Primos and Records side by side, but I think that in the wet the Records must hold an advantage. My bike is currently equipped with Primos, but on several occasions I skidded in the wet, in particular when going over white lines on the road. The amout of rubber on the road cannot be the deciding factor for the behaviour in the wet of the tyre. The friendly policeman is going to explain that to you, should you be caught with bald tyres on a car. Raintyres in F1 also have a tread. The reason is that the tread can displace water much better than bald tyres, and aquaplaning is prevented . Surely the same must be true for a bicycle?
• David Hansen, Oct 1998:
  I agree. There are several places I ride were Primos will slip sideways, such as badly laid setts, where Records will not slip. This is undoubtedly due to the tread.
• Len Rubin, Oct 1998:
  No! True "hydroplaning" only occurs when lower contact patch pressure per square inch exists (e.g. the combination of the very much wider tires used on motor vehicles, while travelling at high speed on slick freeways, where the pressure per square inch of tire on the road is very much lower); bicycle tires have HIGH contact patch pressure, due to much narrower tires and fewer of them, plus no high-speed lift effect--hence the rarity of airfoils on Bromptons!) On very wide off-road bicycle tires, tread is quite useful, but, despite personal anecdotes and belief/intuition, in lab and road tests, it proved unhelpful on narrow (1-1/4" and below) tires on paved surfaces. The tire's construction (tread hardness, tread and sidewall suppleness) and tire pressure are far more significant.
• Rob Cope, Nov 1998:
  The Moulton list didn't produce much direct Record/Primo experience but suggested the 20" Primo (APB size) is noticeably inferior in wet/ice to equivalent Continentals. So I continue to dream of a 16" Conti (fat chance). Still think the Primo is the best of the limited choice we have.
• Ian Oliver, Aug 2000:
  On tarmac they were fine, but on cobbles and raised manholes they were lethal. We have loads of both in Leeds.
• Chris Newport, Aug 2000:
  I found a Primo on the back gripped noticeably worse in the wet than a Record, to the point where I didn't feel safe.
  

Which one is quicker?

• Leonard Rubin:
  There is a mountain of evidence by now, both scientific (various competent comparison tests) and anecdotal to establish the advantages of the Primos over other tires. The advantages stem from the following well-known principles:
  1. Reduction in frictional loses through hysteresis (a tire's internal resistance to flexure) translates into greatly improved rolling resistance. This means that a tire with a suppler sidewall will roll better than a stiff one, and this is far more significant than pressure--especially in a small tire, where LOWER pressures often yield LOWER rolling resistance! This is due to better compliance with the irregularities of the road (think of it as a suspension advantage conferring the ability to travel at a higher speed.)
  2. Reduced rotational mass (especially at the wheel's periphery) translates into substantial improvements in acceleration, braking and handling.
  These effects are widely accepted both on a theorectical basis and--more importantly--on an experiential basis. This does not mean, of course, that all parties, under all circumstances will immediately realize these differences. Given a fair trial, however, the Primos will prove themselves to any remotely objective rider!
  The most important element in Norman's communique, though, is the benefit-negating high-pressures he cited. These tires will perform better under most real-world road conditions at lower pressures (in the range of 45-65, depending on rider weight and road surfaces)!!!
  Lastly, although I (and many others here) have had great luck with the casings so far, it is rather intuitive that lighter, thinner tires will probably not be as long-lived as heavy, thick ones. Bear in mind though, that the specific rubber compounds and construction techniques used do affect the wear considerably, and the greater expense of high-quality tires is often due in part to higher costs for improvements in both of these critical areas.
• Leonard Rubin, Aug 1997:
  [sort of laymen summary of the above] People are focusing on the wrong attribute; the Primos have reduced rolling resistance because of the suppler casings, good rubber compounds and overall performance design, which all result in reduced hysteresis losses.
  The pressure rating is often a general indicator as to the quality of the casing, but as previously discussed here, above a certain point, increases in (operational) tire pressures do not correlate to decreases in rolling resistance in small tires on real roads -- except inversely!
• Norman Tulloch, Aug 1997:
  I changed to Primo tyres and inflated them to the 85psi indicated on the sidewall of the tyre. However, I found the ride to be fine on perfect road surfaces but uncomfortable and inefficient on anything less good.
  After advice from other Brompton-Talk people (David Henshaw and Len Rubin?), I reduced the pressures to 70psi rear, 60psi front. These lower pressures make the bike much more comfortable and allow it to run more smoothly and efficiently. Though initially I was very doubtful about the Primos and seriously considered changing back to the Raleigh originals, I now agree that the Primos provide a genuine improvement in the Brompton's performance and comfort - but not at 85psi or above.
• David Henshaw:
  May I refer all Brompton-Talkers to 'Folder' magazines issues 17 and 18 which feature, I believe, the only comprehensive tests of the Primo fitted to a Brompton (and a Moulton for that matter).
  Yes, in our experience, Len 'Folding Bike' Rubin is quite correct. The Primo really does roll better with just 60psi for a rider of average weight. At this sort of pressure the tyre gives a softer ride AND better rolling resistance than the Raleigh Record. The high pressure capability is only really useful for heavier folk who will experience the same rolling resistance/ride compromise at higher pressures.
  Another advantage of the very supple sidewalls is that high rolling resistance doesn't kick in until the tyres are almost dead flat. Jane and I did a regular 10 mile cross-country ride faster than ever before this afternoon, but I only had 'Brompton pump' pressures in my rear Primo following a puncture - that's 40psi. It makes remarkably little difference. [...]
  After several thousand miles, we wholeheartedly recommend the Primo - it's lighter, it handles better, rolls better and looks better. A word of warning though - the frail sidewalls don't take kindly to dynamos and the 'bead' is very easily damaged by ham-fisted removal. Otherwise they last and last. Strangely, some people haven't bought them yet.
• Custfold, Aug 1997:
  Primos also weigh over 30% less than the OEM [Raleigh] tyres, and there is a common belief that 1 oz off the rotating mass, is worth 1 lb off the dead weight of the bike. A bit like the striving in larger vehicles to reduce the unsprung mass and improve handling .
• Custfold:
  For footwear fetishists.

  Tube weights Brompton OEM - 108g Michelin 400A - 80g

  Carcase weights Raleigh Record - 340g (OEM) Primo 1.375" - 202g

• Zach Kaplan:
  

  TUBES: Kenda 47-305 schraeder (16x1.75) 107.3 g $5 (Taiwan) Kenda 37-349 presta (16x1 3/8) 93.6 g $5 (has been used successfuly in Moulton tyre) Kenda 37-349 (16x 1 3/8) shraeder 99.5 g $5 (Taiwan) Primo 19-349 (16x1) presta 56.8 g $5 (has been used successfully in Primo 37mm tyre) Schwalbe 28-47-355-400 (18") presta 96.6 g $6 (This tube fits the Schwalbe City Marathon 406 and Continental GP 406 among many others. It is made in Korea) Wolber-Moulton 32-369 (17x1 1/4) presta 86.7 g $15 (France) Wolber-Moulton Pacemark Sealant filled prototype 32-369 (17x1 1/4) presta 141 g $20

  TYRES 305mm: Cheng Shin C-639-5 Nylon 37-305 (16x1.5) 2.5 bar (35 psi) 344 g $12 (block tread pattern, black wall, made in Taiwan, standard equipment on BikeE) Hwa Fong Rubber Duro 47-305 (16x1.75) 5 bar (75 psi) 322.5 g $12 (square block tread pattern, black wall, great higher pressure upgrade tyre for BikeE front wheel and BOB trailer wheel!) Schwalbe City Jet 54-305 (16x1.95) 5 bar (80 psi) 348 g can be imported for $30 (slick with grooves, black wall, the best 305mm tyre available!)

  TYRES 349mm: Primo 19-349 (16x1) 7.5 bar (110 psi) 123.5 g $20 (smooth herringbone tread pattern, skinwall, made by Cheng Shin in Taiwan. Note: this is an ultra narrow small diameter tyre and should only be used on the front of a LWB with a light rider or on smooth tracks, also comes in 400mm and 451mm versions) Primo 37-349 (16x1 3/8) 6 bar (85 psi) 215.5 g $21 (smooth herringbone tread pattern, skin wall, made by Cheng Shin in Taiwan)

  TYRES 369mm: Wolber-Moulton Ribbed 32-369 (17x1 1/4) 7.5 bar (110 psi) 260.4 g $32 (linear ribbed tread pattern, black wall, made in France by Wolber which is owned by Michelin)

• Custfold, Apr 1998:
  The tubes I sell are Michelin ref F432308 - with Presta valves and rated for 32/37-349 or 400A. They are no longer generally available in UK but may be available in France at your LBS. I get over the problem by importing very large batches as a special order to the UK. There is also a Primo tube for the 19-349 tyre which will fit the 37-349 if pumped up to arounf 6.5-7bar to make sure it stretches to fill the tyre I also have these but some people prefer the reliablity of a less stressed tube at the cost of 30 gm/wheel. In Netherlands Fiets A Parts has stocks of tyres & tubes and is supplying many LBS.
  Working back through the sums - the Michelin weighs around 80gm against the OEM tube (Raleigh - made in Taiwan) at 110gm. The Primo weighs 57 gm.
  Primo tyres weigh around 220 gm against 360gm for the OEM Raleigh, hence the dramatic improvement in decreased rotational inertia.
• Peter Amey, May 1998:
  Primos are dearer but the rolling resistance decrease really is significant and noticeable (my daily commute reduced by 7% immediately I fitted them).
• See Riding issues - Rolling resistance tests
• Custfold@aol.com, Aug 1998:
  See the Moultoneer review of 406 size tyres which highlighted the Primo 37-406 as equivalent to the discontinued (?) City Jet and priced £1.50 cheaper per tyre, to realise what tyres are costing in special types.
  Currently the Primo 19-349 is being used on one Brompton with a light (under 7 stone?) rider who has recorded some fine better times on regular runs - watch out for developments. The specialist size is however more expensive still than the 37-349.

Which one lives longest?

• Channell Wasson:
  Primos last well, appear to last longer than the Raleigh Record tires, but the Raleigh tire is also good for less than 1/2 the price of Primos. Dynamo does not slip on Raleigh tires.
• Peter Amey, May 1998:
  I use Primos fairly hard (10 miles each way on gravel tow path + roads). I had the cords go in one (monster bulges) quite early but have worn another right down to the canvas with no structural problems after several thousand miles.
• A2B, May 98:
  For those who think Primos do not last, I've only just taken off that original front tyre after about 5,000 miles. In the end it made me nervous, but it only ever punctured once. I don't have shares in the company (!), but I think they are the most wonderful cycle accessory ever invented. After a following wind, that is.
• Stein Somers, May 1998:
  [...] the evening after I put on the Primo's, one was severely cut on a bridleway. I had to greatly reduce pressure or the tube would peek out of it. Later I spotted another small cut, and there's also one on the other Brompton (caused by a metal object). Otherwise I've only had a cut once, at a time 16" wheels were deemed normal for my age :)
  In defense of the Primo, later in the Winter Gardens I picked up a wooden icecream spoon, smoothed the edges and fixed it on the inside of the tyre with a "rustine". It's still fine so I stick with Primo.
  Later (July) the icecream spoon had given all it could so I super-glued a patch of strong nylon fabric to the inside of the tyre. It's still allright.
• David Edge, May 1998:
  Our four Primos have been ok, except for one which burst a sidewall coming down a stony path at Folder Forum.

How do they resist punctures?

• David Henshaw, Jul 97:
  Contrary to Channell's view, I think they [Primo] ARE more puncture-resistant, but it's very hard to be sure. All I know is that I have only mended two punctures in 18 months and 3,500ish miles. Under most circumstances the rolling resistance of the Primo is noticably lower than the Raleigh, and it stays satisfactory down to quite low pressures, so you can get comfort AND speed.
• Peter Amey, May 1998:
  Puncture rate about the same as Raleighs. I have had the cords go in a Raleigh as well. I would say there is little to choose in robustness and puncture resistance.
• David Henshaw - A to B Magazine, Jul 98:
  This subject comes up again and again.Some people get a lot of punctures with Raleigh tyres and some don't. It's not even obviously mileage linked, but weight seems to play a role - if you are heavy you will puncture more.
  Primos are definitely better (for most, but not all, circumstances) because the rubber is of a uniform thickness, whereas the Raleigh has a very thin carcass in the tread grooves. These trap thorns and bits of glass - just try having a look.
  However, it does seem Primos are more susceptible to slashes from glass fragments and a few city cyclists have gone back to Raleighs disappointed.
  Here in the country, where glass is rare, but thorns are common, we use Primos exclusively and we've never looked back.
  Here's our record for the last 12 months. I don't know how old the tyres were at the start - I'm just glad I kept a record:

  ME	Glass	(rear)	26/8/97	0 miles
  	Glass	(rear)	02/1/98	540 miles
  	Gravel shard	(rear)	17/5/98	1,250 miles
  	Rear tyre replaced		14/7/98	1,570 miles

  On my second bike, I've ridden a further 1,000 or so and the Raleigh Records have punctured at least four times (no speedometer)
  

  JANE (bike 1)

  Gravel(front)

  5/8/97

  and no further punctures in 890 miles
  

  JANE (lightweight bike)

  No punctures since built in September 1997 (with Michelin tubes) over a mileage of about 1,400 miles. However, the rear tyre was replaced at about 1,000 miles following damage, but it did not puncture.

  With Raleigh Records we were mending punctures every 200-400 miles or so. We're absolutely delighted.
• Rob Cope, Jul 1998:
  Raleigh Records are probably as good as any £5 tyre can be in this day and age: they are astonishingly good value, but long in the tooth. The tread design tends to pick up & hold glass fragments which can then go deeper: checking tyres regularly (espec if you've just rolled through some glass) pays dividends with all designs. [...]
  I do find Primos puncture less, possibly because the smooth tread sheds debris. When they do puncture, they are far easier to get off 'n on: lighter more modern beading again. In fact they can often be mended without removing the wheel, something I have never persuaded a Record to do.
• Martin Whitfield, Jul 98:
  The puncture rate for Records is similar to that for Primo tyres so there is no solution there. The best prevention is to keep them well pumped up - 60 psi should do it. It also makes pedalling easier.
• Scoman, Dec 1999:
  The first 1,200 miles were on the stock tires. They were fine. I wouldn't replace them until they wore out. Been on the Primos for about 500 miles now. Seems to be a difference of opinion on the board, but I found the Primos to be a bit more flat prone. Got about six flats on the records before for I replaced them. Had three on the Primos within the first 100 miles. However, I have since put "skins" (tire liners made of kelvar) inside the Primos and haven't had a flat in the last 400 miles. Over the same period I've dug out about 20 bits of glass (4 pieces just this morning!), so I think the skins work. Also, when you do get a flat, the Primos are MUCH easier to get off the rim.
• Ian Oliver, Aug 2000:
  [Primos] also suffered with all the broken glass I have to ride over - bits were getting pulled off and then glass was causing many punctures.

How hard is puncture repair?

• Mindak, Sep 1999:
  The Raleigh tyres are *very* difficult to remove, especially when they are new. I wouldn't attempt to repair a puncture on Raleighs with the wheel in situ. The tyre levers may not be the problem. I have broken a sturdy plastic tyre lever on the Raleighs, and you cannot use metal ones because the aluminium rims are easily damaged.
  The Primos are much better, in fact you can remove them on my bike with your bare hands without too much efford. A number of members on this list repair punctures without removing the wheel. I have tried both methods and prefer to remove the wheel, because the couple of minutes saved is in my mind not worth the more complicated and error prone method you describe.
• Rob Cope, Mar 1999:
  Primos are much easier to get on & off: you can often do a repair without removing the whole wheel.

How do they cope with tyre-side bottle dynamo's?

• Channell Wasson:
  Only problem I have had with primo tires was while dynamo was operating for lighting. The dynamo rotor would not properly grip the tire wall and showed signs of wearing through the gum wall as a result. To solve this I put a smear of silicone on the tire wall and covered the rotor with a piece of 1" bike tube which I glued to the rotor. Now all works well and is also quite quiet while operating the lights.
• Channell Wasson:
  My dynamo was stuck with glue. I freed it up and installed an o-ring on the rotar. Now it works fine, but with a new tire. I wore a hole in the other Primo with the stuck dynamo rotor. Seems you have to get friendly with the system. With the neoprene o-ring (use two o-rings if you like and super glue them on) and a free running dynamo head all works well [...]
• Mike Hessey:
  I too have dynamo problems with the Primo if it rains. Even a little moisture seems to stop it working. Mind you, I also had similar problems with the original tyres. [..] The dynamo I'm using is the Nordlicht, and despite many efforts to overcome the slip problem by altering the position, it still slips!
• Peter Amey, May 1998:
  My only concern is sidewalls and dynamos. I have a Nordlicht with narrow rubber wheel running on the rim at present but it is not really satisfactory there; dare I move back to the tyre sidewall?
• Martin Whitfield, May 98:
  My experience with a AXA HR dynamo, which fits on the original bracket with no problem at all, is that the Primo quickly wore out and the sidewall shredded. Switched back to Raleigh Records. For me, the Primos were a bit of a disappointment all round, but I know that others are more enthusiastic. Raleighs have now been restored on both wheels due to the front Primo wearing out.
• David Edge, May 1998:
  We have them on the front of all three bikes, but use Records for dynamo rears. I had a Nordlicht with the little rubber ring which wore away to a point and cut a groove in the Record outer. Suggest fit the big rubber replacement ring (Chris Juden says do this from new) and inspect every month in winter.
• Rob Cope, Aug 1998:
  Primos are great but intolerant of sidewall abrasion (just like other quality lightweight tyres). So you have watch for things like misaligned brake blocks - and avoid dynamos. I really don't think they get on well: either you damage the tyre or spend forever adjusting the dyno to get it to work (espec in rain).
  If you want to keep the fitted dyno: stick to the Records, they're still remarkably good tyres for the money.
• Guy Jackson, Aug 1998:
  My dynamo was slipping on the Primos in wet weather. I than got a ribbed rubber cap from a local bike shop (50p English money) and it has worked perfectly ever since. The side walls have not worn any more than the rest of the rear tyre which takes a hammering anyway.
• Roland Elsenberg, Oct 1998:
  Wear due to the dynamo is a problem with Primos. But it is easily solved: Get a cheap rubber cap for the dynamo's wheel. This will fit onto the AXA iQ that the current models are equipped with. It will probably fit the formerly mounted Soubitez, too. Another possibility is the Nordlicht with O-ring shaped rubber-wheel. Unfortunately this is rather heavy and can on the long run break the point the dynamo is screwed on. I chose the simple solution with the rubber cap and it worked for some months 9 km dayly. It will, at a given speed, make the dynamo turn slower, but you will compensate this!
• Norman Tulloch, Oct 1998:
  I use Primos and the Nordlicht with the O-ring shaped rubber wheel (rather like the rubber tyre from an old-fashioned model car such as the Dinky). I like the Nordlicht which seems to me both quiet and efficient. I don't know much about whether this set-up causes fewer wear problems with Primos, but it certainly doesn't solve the problem of dynamo slippage in the wet.
  • Stein Somers, Oct 1998:
    Same configuration here but not the slightest slippage. I must confess that lately my rainy rides haven't lasted even an hour, which is the time it took the original Brompton lights to become useless.
• Stein Somers, Nov 1998:
  I cut a slot in the mudguard (toughest piece of plastic I encountered), moved my Nordlicht up, so that the thin wheel runs on the black skin of the Primo. Surely the rubber wheel is less abrasive than tarmac? I did have to saw away the unused part of the brake drop at the dynamo side (i.e. left side) to maintain proper alignment.
  [Alas it was too late. A few weeks later the outer layer of the Primo's sidewall tore, the inner layer held the tyre together, but the resulting bulging of the tyre imposed replacement.]
• Stein Somers, Jan 1999:
  Last year I bragged about my perfect dynamo set-up (Nordlicht on custom bracket). Now it's slipping at the mere sight of water...
  My last hope: it doesn't like the recently installed Raleigh tyre. I'll give it a new Primo - although it cut the previous Primo through the thin line that its wheel traces - that thin line between love and hate.
• Rob Cope, Jan 1999:
  I have given up trying to get Primos & dynos to cohabit: even if they do not wear through, that thin, smooth sidewall seems to have a coating (anti-UV?) which a dyno (even rubber-wheeled) just will not stick to in wet. I've tried most of the suggested solutions (inc several sorts of roller cap) but I cannot afford to keep replacing tyres.
  So rule of thumb is decide if you want Primos or dyno: not both.

Is there a difference between Primo and Pr1mo?

• Peter Amey, Dec 1998:
  Has the design/construction of Primo tyres changed? I ask because I destroyed one last year with a Nordlicht dynamo. This tyre had cream-coloured sidewalls and the name was spelt with a 1 as in Pr1mo. I had all sorts of plans to change the lighting setup on my bike for this winter but never got round to it. Inevitably I ended up risking the dynamo again and (touch wood) have had no problems at all this year. The dynamo leaves a clean line on the otherwise dirty tyre sidewall but is not eroding it at all. The primo currently fitted has distinctly yellower sidewalls than its predecessors and does not have a 1 in the name.
• Stein Somers, Dec 1998:
  Mine was a Pr1mo, mail-ordered in April this year from St-John Street Cycles. Opposite to the embedded brand and size is a small box with "1846".

Tyre pressure

Optimal pressure

• David Henshaw:
  For example, we suggested 53psi front and 89psi rear for a rider of 230-260lbs. Note, these figures only hold true for the Primo fitted to the Brompton on a 'typical' road surface. For other bikes, tyres, rider weights and surfaces, you need to think again!
  [...] To find the ideal setting for you, refer to 'Folder 18', page 32. With hindsight we appear to have got the figures about right, but it's worth adding a few more PSI to allow for leakage.
• Martin Whitfield:
  I have had my Brompton for about four years and have yet to have a blow-out (touch-wood). I have found that the best trade-off between the an increasing number of punctures and over-inflation is about 65psi. Down below 55psi and punctures increase, especially on the back.
  I have no experience of any other tyres apart from the Raleigh Records which last about 2-3,000 miles on the back and about 4,000 on the front.
• M.A. James:
  Dont go above 75lbs for Raleigh Records Keep regular check ie pump up every two weeks as they go down fast. Min 50 or they wear out quick and its hard work.... Best 100lb tyre is primo 4oz lighter little tread faster and at least 15quid mail order.
• Custfold, Aug 1997:
  My own observation is done by looking down at the tyre (don't do this when moving - unless you are very skilled!) and seeing how much it 'bulges' beyond the rim, and additionally 'feeling' the potential of snake bite bottoming when riding. Optimum pressure is then achieved when there is a slight bulge, and no snake biting on the bumps.
• Dave H, Jul 1998:
  Records sidewall pressur is 55 psi - Brompton suggest 70 psi - most serious riders use as hard as possible, as 55 psi for most riders is way too soggy, and increases snakebite puncture rate very greatly. I ran Records at 90 psi with consequent explosive failures when clinchers separated from tyre. I now use Primos with up to 100 psi when properly seated.

Maximal pressure

• James Crouse:
  My Brompton arrived with Raleigh Record tires that said inflate to 55 PSI. The owner's manual said to inflate the front to 50-70 PSI and the rear to 60-70 PSI. A "Congratulations to you as a New Brompton Bicycle Owner!" letter from C.M. Wasson Co. said to inflate to at least 65 PSI. An additional hand written insert marked "important" in red ink said 80-85 PSI. So I inflated to 85 PSI (my pump is accurate) and you can no doubt guess the rest of the story. BBBBBBBBAAAAAAAAAANNNNGGGGGG!!!!!
• Ted Mallen:
  Me too, James ! Just got in new L-3. Inflated to 85 psi as instructed. After test riding for 10 miles, rear tire blew while proudly sitting in my office. It,also, was a Raleigh Record. It separated at the bead.
• Peter Amey:
  I used 80-85 psi for while but eventually had a tyre develop a bulge in the sidewall (it was quite new too). I have now settled on 75 psi which is bearable for rolling resistance, ok for ride and seems to be safe from unexpected bangs.
• Simongikuk, Dec 1998:
  I have Raleigh Records which I inflate to 75 psi for my daily 14 mile round trip to work across London. No blow-outs so far, just the very occasional puncture. I don't think I've ever inflated them more than 80psi. Which is probably just as well, really.
• Robert Evangelista, Aug 1999:
  I've used [Primo's] up to 105 psi with no problems.

How does over inflation contribute to rim failure?

• Jeff Dauvin, Mar 2000:
  How will the rims stand up to the high pressure? When my rear rim failed at about 2000 miles the shop who repaired said & I had over-inflated my Raleigh Records to 80psi & that had contributed to the failure.
• Stein Somers, Mar 2000:
  A tyre holds the air that, through its pressure, separates rim from road. Pressure works in all directions, so pushes the sidewalls of the rim outwards. The higher the pressure, the thicker the rim sidewalls need to be to resist collapse. But the sidewalls are grinded away by the brake blocks, until at some point they no longer stand up to the pressure. The higher the pressure, the sooner this happens.
• Mark James, Mar 2000:
  The recommended way of testing whether a rim is safe according to technical man at Cycle Touring Club UK is to pump up to well beyond usual pressure tyre unlikely to be damaged etc. If rim doesn't crack etc its good for several hundred miles.

Tyre sizes

• Leonard Rubin, May 98:
  When I worked on the 5th Edition of Sutherland's Handbook for Bicycle Mechanics, one of my pet projects was to shed some light on the traditionally murky area of tire/rim standards. The original practice of naming a rim size for the outside diameter of its tire was workable in the early days, when each country's tire manufacturers were few and their tires similar, and each market kept to itself.
  With the bike boom of the '70's, suddenly rims and tires from different countries, each with its own national tire standard, started to appear in the U.S. Virtually overnight bike shops were dealing with several different diameter rims, all called 26", varying by as much as an inch in diameter, because one 26" rim was named for its mating giant balloon tire's outside diameter, and another for its very different mate -- a narrow club racer! So everyone began carefully distinguishing between "26 x 1-3/8", "26 x 1-1/4" (sometimes referred to as "Schwinn 26""), "26 x 1.75" (rim sizes descended from original use with hooked-bead tire types were supposed to be distinguished by decimal width figures), "650B" ("650" was a European classification for 26" tires and came in various widths with three gross cross-sections categories -- A, B, & C!; some American mechanics referred to these simply as "tandem size".) This Tower of Babble got even worse when, in the 80's, marketing companies like Specialized and Avocet started selling narrow tires for the traditional balloon-tire rim diameters. This led to actual tire diameters that greatly diverged from the their "named" diameter -- it was not uncommon to hear about shops ordering the wrong size tire based on a bare rim that a customer brought in, or distributors, on occasion, shipping tires that would not fit the supplied rims from their own catalogues!
  When I began to advocate the use of ETRTO beadseat diameters in the 5th edition, it was still controversial (many manufacturers already used this terminology, but very few distributors or bike shop personnel did) but when I contemplated the half a dozen different 26" tires (none interchangeable with each other) and the eight 20" sizes, eight 16" sizes, etc. -- all non-interchangeable -- it seemed like it was worth the effort to forcibly re-educate the U.S. bike industry, by reorganizing all charts and listings according to actual ETRTO beadseat diameters.
  Folding bikes generally use a variety of 20", 16" and 14" tire diameters. Green Gear's Bike Friday models use two different 20" rim sizes. Some models use the smaller, more common (at least in the U.S.) 406mm ("20 x 1.75") diameter, others use the larger, less common 451mm ("20 x 1-3/8", although usually paired with the newer, lighter IRC "20 x 1-1/8" tires) size. Their tires are not at all interchangeable. For each of these two 20" standards, there exist only a couple of reasonably high-performance tires for on-road use (you would NOT want to put 406mm department store kiddie tires on your Bike Friday, as most are so horrible that they would reduce the ride of that fine machine to that of a very heavy old junker with snow tires!), with only a bit more variety just beginning to appear, despite decades of sales.
  The Raleigh Twenty used 451mm rims ("20 x 1-3/8"). as did many of the folders of that era (the others used 406mm or sometimes 440mm ("500A")) Early Moultons mostly used the 349mm ("16 x 1-3/8") standard. (The Moulton AM series uses a really esoteric 369mm ("17 x 1-1/4") size (you can only buy tires from Moulton!). Their ATB and newly introduced model use the more common 406mm. Bickertons used the 349mm on the rear and 298mm ("14 x 1-3/8") on the front. A clever aluminum portable (non-folding) commuter bike, the German Kettler City Hopper also used two sizes -- 305mm ("16 x 1.75") front, 406mm rear. Most Hons (Hon Corporation later changed its name to DaHon) used 305mm rims (many recent models use 406mm). The Japanese Bridgestone Picnica uses the 253mm ("14 x 1.75") size (the Japanese market version uses 203mm ("12 -1/2 x 2 1/4", as do most children's scooters.)
  The Brompton choice of 349mm is one of the more common small-diameter standards worldwide (305mm is another). With the advent of Primo's lightweight, high-performance tires, these sizes are finally becoming attractive, because, as any automotive engineer can tell you, you should design a vehicle around the tire you intend to use with it -- indeed, I would assert that it has historically been the lack of high-performance tires that has held back the progress of small-wheeled bikes (one of the reasons Alex Moulton developed his own tire was to ensure the optimal performance of his AM bikes.)
  To return to the original question, either 406mm or 349mm would be excellent choices, as they are they are each popular standards in several markets, but it is really the design and construction details of THE PARTICULAR TIRE ITSELF that will determine to a very large extent how a bike will feel, handle, and perform, so choose very carefully.
• David Edge, Sep 1998:
  According to Recumbent Cyclist UK, the following sizes exist:

  16"	16x1.75	ISO305	used on BikeE
  400a	400x47A	ISO340
  16"	16x 1 3/8	ISO349	used on Brompton and Vision

  In the CTC handbook Chris Juden lists:

  American	16x1.75x2 = 47-305
  Metric	400A = 32-340 and 400x35A = 37-340
  Imperial	16x1 3/8 = 37-349

  which I think corresponds to the RCUK list. Anyway, as far as I know, the first of the three is the balloon tyre used on the Dahon and the last is the Brompton.

The Brompton Folding Bicycle FAQ - please comment