Preventing problems - taking care of your Brompton

Contents:
When you just purchased a (used) Brompton Retension spokes Toss out abbrasive brake blocks Grease Regular checks Basic brake care Infrequent inspections (but do it sometimes!) Replace the brake cables Check the handlebars Check the frame clamps Check for frame cracks Check for loose pivot bolts Check the front carrier block Check suspenion block pretension Check rim thickness Check for handlebar cracks Grease the front hub and tighten its cones

Contents:

When you just purchased a (used) Brompton
Regular checks
- Basic brake care
Infrequent inspections (but do it sometimes!)

When you just purchased a (used) Brompton

Spotlight on brakes - A little modification I made to keep water out of the brake cables

Retension spokes

if you are not a lightweight person, to prevent Spotlight on wheels (rims, spokes and hubs) - Broken spokes

Phil Gough:
I have now had the rear wheel replaced (using the Sturmey Archer steel hub with brass washers again) because the wheel had become so sloppy that the spoke holes in the original hub had become ovalised and rendered the it useless. That was my lesson learned, that spoke tension should be part of regular checking routine.

Toss out abbrasive brake blocks

Unless you're planning to regularly perform Preventing problems - taking care of your Brompton - Basic brake care, read about Spotlight on brakes - Alternative brake blocks.

Grease

Jonathan Brickley, Feb 2000:
I also found when servicing the bike that my dragging brakes were caused by a complete absence of grease on the caliper pivots.....it's well worth dismantling and greasing from new!!

Regular checks

Spotlight on the (hub) gears - Adjusting Sturmey Archer hub gears

Basic brake care

Larry Chinn - The Freewheel, Sep 1999:
If you look at your rims, you will see bits of aluminum looking like tiny bits of glass impeded in the pad. File them down until they look clean. Sandpaper your rims similarly removing all remnants of dirt and rubber.
You need be much more vigilant about clean rims and pads on a bike with fenders
Also quality of the pad and rim make a big difference much like tires and anything else on a bike. Despite the fact I have Shimano XTR V-brakes and Mavic MA-2 rims on my 700 cm hybrid, I sandpaper the rims and file the pads to prevent squealing and improve braking, especially in the rain.

If (like me) you're too lazy to do this, get some softer brake blocks (Spotlight on brakes - Alternative brake blocks).
Or do it less often? Asked how he'd taken the B over 2,000 mi in a long trek he did some years back, Channell Wasson reports:
I have had no problems with the Brompton brake blocks. Keep the rims clean (steel wool is useful) and sand any glaze off the brake blocks. I do this occasionaly.

Infrequent inspections (but do it sometimes!)

Replace the brake cables

The pre-March 2000 brakes with pear shaped cable ends break easily (Spotlight on brakes - Brake cables) Don't risk it!

Check the handlebars

Before they break (Spotlight on handlebars - Broken handlebars)

Custfold, Aug 1997:
The point about inspection cannot be stressed (sorry no pun intended) enough. The failure of early B bars is preceded by a very noticable crack line -usually along the neutral axis of the bend, for around 3-6 months before it fails.
The top of a loaded beam is in compression, the bottom is in tension (and vice versa for cantilevers). As you approach the centre of the beam they cancel each other out until at the neutral axis the result is zero, ie neither tension nor compression. This is the reason why rolled steel beams are "I" (capital i) shaped, because you need the most material at the top and bottom where the stresses are highest. And why if you're putting holes in timber floor joists to run cables, pipes etc, you should always drill through the centre and not notch the top or bottom.
There's no reason why bars should fail at the 'neutral axis'. I suspect this is a mis-use of the term because obviously you would expect failure where the stresses are highest. Failure is caused by the torsional stress set up in the horizontal part of the bars when you push or pull against the handles, which is highest on the surface of the bar and zero at the centre
Custfold, Aug 1997:
Oops I made a wee assumption, which may not hold absolutely true. The line appears on the neutral axis of the bend where the alloy handlebar tube has neither been stretched or compressed, it was a crack, as the failure of the bars focussed onto it from upper & lower faces at the clamp. Now in use it may be that the 'neutral axis' of the bend may focus stresses, because the tube is deformed from a true radius to have thicker walls, and larger diameter in that plane and not be a neutral axis of the whole unit under load. Stress modelling program anyone?

Check the frame clamps

Custfold:
Did spot an aesthetically displeasing Brompton front main frame clamp, on one machine - possibly a mis matching of assemblies/tolerances, but the 2 halves did not meet evenly in the clamp - possibly damaged pivot pin, or mis drilled holes - and suggested the owner referred back to check this was not a damaged or defective finish bike, which had got out. Do however check the clamp plates occasionally for damage if the bike is intensively used. One of my earliest machine's plates (1989) started to show signs of the alloy clamp cracking, and tightening right to the frame (no gap). These pieces are crucial to keeping the frame stresses evenly distributed (the bike can be ridden with them loose but it is (sic) not recommended and very noticable in the ride quality). Later issue clamps are not anodised - could this reduce the potential skin effect of the harder Al2O3 ?
Such a series of annual checks and visual awareness is just the same as one would do for the UK motor vehicle annual test after the vehicle reaches 3 years old, and would include examining highly stressed points at frame 'junctions' and rear pivot for deformity, and large areas lifting paint (a previously noted indicator of a crack or movement of the metal below). Brake cables should be examined, as should rim wear etc - above normal brake checks and spoke tightness. Over a long period wear will also occur in the rear pivot pin and bearings, but this does tend to be relatively minor - perhaps dismantling at 4-6 years for a check on a heavily used machine might reveal a need for renewal.
Peter Amey, Aug 1997:
No sign of a crack in my T5 handlebars (touch wood) but I did get two lovely, propagating fatigue cracks in one of the aluminium frame clamps after about 3000 miles of hard use. These are worth checking - the main frame tube folding in half at speed would make even handlebar failure look tame!
David Henshaw, Aug 97:
On the subject of fatigue failure, someone mentioned the hinge clamp plates. It's worth inspecting these on older machines, as they do eventually develop cracks, but I have not heard of a catastrophic failure. However, Dave Holladay has broken just about everything else on a Brompton, so I'm sure he can correct me on that. All alloy parts that 'work' should be replaced after high mileage - I replaced my plates at about 8,000 miles, still crack-free, but a bit the worse for wear.
Custfold, Aug 1997:
Again I can only point out that looking at the clamp plate when you tighten it gives a clue (a crack in the corner) well before failure, and the other clue is that the clamp will 'bottom' onto the hinge plates, which will then be slack, and only a completely insensitive rider will not notice the hairy handling. This is akin to not tightening the main frame clamp before riding off (do not try this at home children). There are 2 types of plate - shiny (new) and satin anodised (old) IIRC. I have changed 1 main frame clamp plate in 7.5 years, during which I've broken 2 main frames, and front sections. NB you can tighten the clamps whilst riding should you forget this minor detail, it doesn't do the hinge plates much good though :-(
Custfold, Jun 1999:
My second clamp this year has been changed - split half way through and the front kept moving when braked hard - check those clamps as a regular detail you heavy riders.

Check for frame cracks

David Hansen, Jun 1999:
[...] a crack between the weld and tube in front of the hinge. The crack was around about half the circumference of the weld. Presumably the ride had aggrevated a crack that was spreading slowly.
Custfold, Jun 1999:
Score on this failure with Holladay Bromptons - 4 units - now avoided by sweating on an outer sleeve - major stress raiser in 2 points - abrupt change of section & material in joint from tube to hinge casting, and HAZ for that little loop that hooks the front brake cable away under the frame.
Watch also for a smile under the joint from main tube to y branch for b/b - early frames had less meat to form the joint and a number parted - the failures are usually noticed early by bike crabbing along road out of track, and pedals hitting ground on corners (fixed wheel freaks will appreciate that whatever one rides one keeps pedalling out of habit)

Check for loose pivot bolts

They are threadlocked, but can work loose under heavy use. If they are, hurry to the dealer or carefully do the reverse of Maintenance at home - Removing the rear triangle.