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June 2018

Bicycle brakes get better…mostly

by John Allen

Bicycle brakes have come a long way since the days of wooden-wheeled boneshakers with steel tires, but change does not bring perfection in this world.

Some history

Most early bicycles had only a fixed gear, or a spoon brake, which pressed on the tread of the tire. High-wheeler bicycles couldn’t benefit from a powerful brake anyway, as it would only pitch the rider forward from a high perch.

With the 1890s and the safety bicycle came the coaster brake, popular in the USA, Germany and the Netherlands, and rim brakes, most popular in the British isles. Coaster brakes were a major improvement over spoon brakes, but overheat on long downhill runs. So do all other hub brakes except for disc brakes and the very large drum brakes sometimes seen on tandems.

English three-speeds became popular in the USA following World War II, much so in the Boston area. These represented the first widespread exposure to hand-lever-operated rim brakes in the USA. But the long-reach sidepull brakes on steel rims of typical three-speeds offered poor leverage. The rims were as slippery as ice in wet weather, and prone to damage which made the brakes lurch and grab. I’m old enough to remember! My own first bicycles as an adult were three-speeds, and the braking ranged from marginal to terrible depending on rim condition.

Bicycling took a turn upward in the USA with the rise of the baby-boom generation, but fashion and marketing oversold the American bicycle market on imitation racing bicycles. The run-of-the-mill 10-speeds of the 1960s and the 1970s bike boom generally had good-quality rim brakes, but steel rims.

Only high-grade derailleur-equipped bicycles had aluminum rims until the 1980s, and wheel true had to be excruciatingly accurate for braking to be even, because the rims had angled sidewalls, and any departure from roundness made them wedge the brake shoes apart. French Super Champion Model 58 rims, the first common aluminum clincher rims with parallel sidewalls, first became available in the mid-1970s.

The mountain-bike phenomenon brought other changes in technology, not least with the widespread application of cantilever brakes, then direct-pull brakes and now disc brakes.

All-around advice

So, here we are now.

Any bicycle should have a rear brake capable of skidding the rear wheel (but to spare the rear tires, do it only briefly as a test). The front brake also should be powerful but you need to be careful in using it – more about that in another article. Operation should be smooth and predictable.

Cable failure – or loss of hydraulic fluid -- disables any brake – which is why every bicycle should have two separate braking systems, and brakes should be serviced from time to time. Anywhere a cable is repeatedly bent back and forth – on a brake lever, pulley or brake – it is like bending a paperclip back and forth. The cable will fail sooner or later. Cables should pivot where they attach, and the pivots should be kept lubricated. Cables should be replaced periodically.

Rim-brake issues:

A traditional cantilever brake without protection for the transverse cable. Tolerable with a smooth tire, but…

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  • Brake shoes of cantilever and direct-pull brakes (with the pivots on the fork or frame, closer to the hub than the rim) migrate downward as they wear. The brake shoes can dive under the rim and catch on the spokes. So, check alignment frequently.
  • A direct-pull brake (also called V brake)
  • Both brake shoes of a centerpull brake and the off-center pivoted brake shoe of a dual-pivot sidepull brake migrate upward toward the tire as they wear. Check alignment periodically to avoid a potential blowout.
  • A dual-pivot sidepull brake. One pivot is off-center.
  • A centerpull brake. Both pivots are off-center.
  • Disc brake issues:

    Disc brakes are much preferable to rim brakes for off-road use in the wet and mud but introduced new issues. A disc brake stresses the front fork heavily. It can loosen a quick release and pull the front wheel out of the fork, or put a quick-release lever which opens too far into the rotor – leading to a Trek recall, but not only a Trek problem. A large percentage of CRW members is now riding bicycles with disc brakes, but I’ll make a case here for lagging behind the bleeding edge of progress. This way, other people, not you, get to experience early-production bugs. And they have happened.

    You need to be very careful to check that the wheel is secure with a front disc brake. If the bicycle has a through axle – with holes rather than slots to secure the wheel in the dropout – good. That will prevent the wheel from coming out. Otherwise:

    Exposed-cam quick release

    A Shimano internal-cam quick release

    More info
    More about rim brakes is at https://sheldonbrown.com/rim-brakes.html and linked pages.
    More about disc brakes is at https://www.sheldonbrown.com/disc-brakes.html
    More about quick releases is at https://www.sheldonbrown.com/skewers.html

    Be safe out there!

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