SECTION K: ROUTINE REPLACEMENTS.
Planned replacement is advised to ensure both safety and good performance. The suggested
intervals between replacements are for bicycles subjected to normal use: the most appropriate
timing depends on the conditions of use and your riding style.
1. ALUMINIUM COMPONENTS: as on other lightweight machines, aluminium alloy is used in
the construction of the Brompton, and this material has a finite life before failure. In normal use,
the risk of aluminium fatigue failure is remote, even after many thousands of miles. However, the
risk of failure increases with use, especially with hard riding or other severe loading: as such a
failure could cause injury, the hinge clamp plates, handlebar and chainset should for safety be
replaced every 5,000 miles (more frequently on any machine subjected to hard use), and we
recommend that these items are anyway checked regularly. For the handlebar, an alternative is to
fit a cross bar (see Section M).
2. Transmission: if the chain is allowed to stretch unduly, through lack of lubrication or long term
wear, power transmission will be inefficient and rough and the sprockets will also wear quickly. A
new chain is not expensive: so replace every 2 - 3,000 miles (or sooner if it has lacked lubrication
or been used in harsh conditions). If you have allowed the chain you are replacing to stretch
unduly, you will almost certainly have damaged the rear sprocket(s), and possibly the chainwheel
too: these should be checked when fitting a new chain and if worn should be replaced at the
same time as fitting the new chain.
3. Brake cables: these do not have an indefinite life, and to reduce the risk of brake cable failure,
replace the inner cables at intervals of 4,000 miles or less. If there is any doubt about the free
running of the cables, the outer cables should also be replaced. New outers should be exactly the
same length as the original cables, with the correct terminating ferrules.
4. Gear cables: though less safety critical than brake cables, the hub-gear inner control cables
should be replaced at the same interval as brake cables.
5. Tyres: the risk of punctures increases with the mileage covered, as the tyre accumulates small
sharp particles in its tread. You should reckon on replacing the rear tyre every 3 - 4,000 miles and
the front tyre every 6,000 miles.
6. Lighting on the T-type: a) repeated flexing of the wires around the rear hinge when folding
eventually causes failure - replace the wiring loom connecting the dynamo to the front light at
intervals of 7,500 miles: b) front bulb and dynamo: these can have a very long life between failure,
but performance deteriorates - replace after 250 hours.
8. Suspension bush (flanged bush under the suspension block): 10-15,000 miles.
