Rim brakes stop the bike by clamping the wheel rim between two pads. Disc brakes have a calliper that clamps a disc between the pads, similar to a motorcycle brake .
Stopping power is not a big issue to compare. All modern brakes work well, even with 20kg on board.
The real issues are;
· Braking in the wet,
Braking in the wet with a rim brake requires touching the lever to wipe away water before the pads will grip enough to stop the bike.
Disc brakes work almost immediately. Any water that might be on the disc is squeezed away through holes.
Wear on rim brakes are mostly the cable, pads, and the wheel rim itself.
A cable-operated disc will wear cable, pads, and the pivot in the calliper. The actual disc will last many thousands of km's before showing any wear.
A hydraulic disc has less moving parts and only wears brake pads.
Maintenance on a rim brake is cable lubrication & adjustment, pivot lubrication & spring tension on the brake arms, cleaning the wheel rim, and replacing pads.
A cable-operated disc needs cable libration & adjustment, pivot lubrication & spring tension on the calliper, and replacing pads.
A hydraulic disc needs no maintenance at all apart from replacing pads, and changing the fluid once a year.
Repairs on a rim brake will usually just be a broken cable.
Repairs on a cable-operated disc will typically be a broken cable or calliper.
Repairs on a hydraulic disc would usually be a damaged hose or leaking seals.
Cost is relative. Rim brakes are dirt cheap, cable-operated discs can be expensive, and hydraulic disc brakes will be expensive.
Tips and Gripes:
Rim brakes create black grime when riding in the wet. This is the pads wearing away the alloy rim, and it makes a mess all over the wheels. Disc brakes are very clean.
A buckled rim or split tyre will interfere with a rim brake, but a disc brake will be fine.
Rim brake spares are simply cable and pads.
Cable-operated disc spares are cable and pads, although a spare calliper might be a good idea. The calliper can be disassembled for repairs.
Hydraulic discs are a sealed unit from lever to calliper and the design is almost maintenance free. They are quite tough and not likely to fail. Carry spare pads, and sometimes a bleed kit.
Unless you have your own workshop space, and the know-how, hydraulics need to be serviced by a qualified technician, which could be expensive.
Rim brakes are easy to find cheap parts and do road-side repairs, but discs are definitely a big improvement. It's truly wonderful being able to stop well in wet conditions and continue riding with a buckled rim.
The idea of a hydraulic disc brake is excellent, but not in less-developed areas that are a long way from good bike shops.
In my opinion, a good quality cable-operated disc brake brings both the maintenance and quality braking performance that a touring cyclist really needs.
Source by Axel Schaar