http://www.active.com/cycling/articles/brush-up-on-your-bike-braking-skills-877520
One of the most important skills to learn in cycling in how to brake effectively and safely on steep downhills. There's more to proper braking than just frantically squeezing the brake levers; knowing how to stop could even save your life.
Here are some tips to learn how to use the front or rear brake in a more effective manner and how to brake under various road and environmental conditions:
Front and Back Brakes
Walk a few steps, wheeling your bike along next to you. Apply the front brake hard. Release it, keep walking and then apply just the back brake hard. You'll notice that the front brake is by far the more powerful one (it has about three times the strength of the rear one), but that applying it hard makes the back wheel lift.
Out on the road that lift can turn into a somersault. You may also have noticed that applying the rear wheel makes it lock; on the road that can send you skidding.
To achieve controlled braking, you should use both the front and back brakes, and sit well down on the saddle, putting your weight over the back wheel to stabilize the bike. If you feel the bicycle skidding, release the brakes a little before re-applying them.
Feathering
Practice feathering, a technique of lightly and rapidly alternating pressure and release of the brakes; this prevents brakes from locking while controlling your speed. Feathering is also useful on long descents when continual pressure can cause wheel rims to overheat, glue on tubular tires to soften, and tires to burst.
On wet roads, feathering helps to dry wheel rims. Avoid cornering and braking simultaneously. If there's an emergency and you really must brake in a corner, put the pressure on the back brake; skidding is preferable to going over the top.
Get Familiar
Different makes and types of brake respond differently; the way they work can be influenced by, among other things, the type of rim on the wheel, wet weather, the load on the bike, the speed you're moving at and the gradient of the road. Familiarize yourself with the way your brakes work under different conditions; try to judge how long it takes and how much ground you cover before coming to a stand-still from different speeds, and visualize using your brakes in an emergency situation.
If you have children who ride in the rain, get them to measure the different stopping distances for a bike with dry rims and one with wet rims; they'll grasp the implications of this far better than if you simply tell them that brakes work slowly in the wet.
Some important things to know about braking:
- Bicycles take longer to stop than cars do.
- Bike brakes take longer to work when the wheel rim is wet.
- Brakes work far better on aluminum alloy rims than they do on steel rims.
- The best brake pads to use in wet and dry weather are synthetic. Though rubber brake pads have a fair grip on aluminum, they skate over wet steel and result in stopping distances that can be four or five times as long as you'd expect in dry weather.
- If you get oil on the rims, you should get off and remove it before going on.
- Braking has the effect of throwing weight forward and destabilizing the bicycle. In a sudden stop, and particularly if you're going downhill, this can catapult you over the front wheel; this is more likely to happen if it's the powerful front brake that is applied abruptly.
- Abrupt braking on the back wheel can make the bike skid out from under you.
