There are several techniques for efficient braking on a standard, two-brake bicycle. The one most commonly taught is the 25-75 technique. This method entails supplying 75% of the stopping power to the front brake, and about 25% of the power to the rear. Since the bicycle's deceleration causes a transfer of weight to the front wheel, there is much more traction on the front wheel. Therefore, the rear brake can exert less braking force than on the front before the rear wheel starts skidding. For a more-detailed analysis, see bicycle and motorcycle dynamics.
If too much power is applied to the front brake, then the momentum of the rider propels him/her over the handlebars, thereby flipping the bicycle. The skidding of the rear wheel can serve as a signal to reduce force on the front brake; a skillful cyclist in effect becomes a human anti-lock braking machine, thus they must use both front and back brakes
Some front brakes have a spring that limits the applied force; this is easier to use but limits the braking force and cannot compensate for changes in brake effectiveness due, for example, to a wet rim or overheated brake disc. On tandem bicycles and other long-wheel-base bicycles (including recumbents and other specialized bicycles), the lower relative centre of mass makes it virtually impossible for heavy front braking to flip the bicycle; the front wheel would skid first.
A skillful bicyclist often will use the front brake alone for moderate braking when riding on a good, paved surface. As the front wheel does not skid in those conditions, the front brake poses less risk of loss of control, and does not cause rapid tyre wear.
In some situations, it is advisable to slow down and to use the rear brake more and the front brake less:
- When unfamiliar with the braking characteristics of a bicycle. It is important to test the brakes and learn how much hand force is needed when first riding it.
- When leaning in a turn (or preferably, brake before turning).
- Slippery surfaces, such as wet pavement, mud, snow, ice, or loose stones/gravel. It is difficult to recover from a front-wheel skid on a slippery surface, especially when leaned over.
- Bumpy surfaces: If the front wheel comes off the ground during braking, it will stop completely. Landing on a stopped front wheel with the brakes still applied is likely to cause the front wheel to skid and may flip the rider over the handlebar.
- Very loose surfaces (such as gravel and loose dirt): In some loose-surface situations, it may be beneficial to completely lock up the rear wheel in order to slow down or maintain control. On very steep slopes with loose surfaces where any braking will cause the wheel to skid, it can be better to maintain control of the bicycle by the rear-brake more than one would normally. However neither wheel should stop rotating completely, as this will result in very little control.
- Steep descents : the slope angle makes the front flip more easily reached, and moreover a front-wheel skid would be very difficult to recover (crash highly probable), whereas a rear skid does still drag the bike without losing too much control.
- Wet weather conditions, when the road surfaces are generally more slippery.
- Long descents: alternating the front and back brake can help prevent hand fatigue and overheating of the wheel rims which can cause a disastrous tyre blow-out, or boiling of the hydraulic fluid in case of hydraulic disc brakes.
- Flat front tyre: braking a tyre that has little air can cause the tyre to come off the rim, which is likely to cause a crash.
It is customary to place the front brake lever on the left in right-side-driving countries, and vice versa, because the hand on the side nearer the centre of the road is more commonly used for hand signals, and the rear brake can not pitch the bicyclist forward. However, a skillful bicyclist does better with the front brake on the side that is less often used for hand signals. In an emergency situation, operation of the brake has to be second nature; an unskilled bicyclist could find reversed brake levers confusing. Fortunately, it is usually easy to switch brake cables.
Read more about this topic: Bicycle Brake
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