We try and limit bike failures during touring by regular maintenance. Our approximate schedule is:
- Regular inspection of bike, including checking for bolt tightness and cables that are fraying.
- Brakes: replace pads (or remove all embedded aluminium) every 2-3000km
- The chain stretches and is best replaced about every 3-5000km otherwise the chain wears the expensive cassette and chain rings prematurely. Chains are cheap.
- The cassette needs replacing every 10,000-15,000km. If indexed shifters are used this will probably be required more frequently.
- The chain rings need replacing every second or third time you replace the cassette. We generally consider changing the gear cables at this time.
On an extended tour, one of the most common and serious failures is rims – often the rear rim. It’s braking against the rim that causes wear, and the side wall can become so thin the rim fails, often with little warning. This failure is also made more likely by a heavily loaded wheel, so it makes sense to carry at least a third of your luggage weight in the front panniers thus lessening the load on the more laddened rear wheel.
Most of the rim wear is from aluminum slivers from the rim becoming embedded in the brake pads. More aluminum from the rim then cold welds to slivers already in the pads, so wear accelerates. Periodic removal of the slivers from the brake blocks (with tip of a knife) or frequent brake pad replacement slows this process.
We use cartridge-style brake shoes to simplify replacement. Ease insertion of brake pads by putting a drop of oil on the receiving slot of the brake shoe cartridge. N.B. Don’t get oil on the braking surface of the pad!
Segment of old rim showing cross-section and 0.35mm dishing of side wall.
This was Chris’s rear rim after 25,000 km.
We inspect the wear of the rim and conservatively replace them when more than a quarter of the wall has worn away (~0.45mm for our Alex Adventurer rims). We also visually check the weld as this is sometimes point at which the rim fails. The reason we believe in changing rims early is that the most likely failure is the pressure of the tire widens the thinned rim and you get a sudden and dangerous blow out. We have found we can get at least 20,000 km from a rim.
We use Shimano XT pedals. We have suffered from several pedal bearing failures while on tour. Luckily these are not catastrophic. Instead the bike gets a clicking noise from the pedal on each rotation that cannot be stopped by tightening the pedal on the crank. After a while this clicking can be like water torture to the rider. We have always replaced pedals within 1000km of onset of clicking. Once we were lucky enough to find a mechanic who repacked the bearings and the pedal lasted several thousand more kilometres.