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2. How Brakes Work
The braking action of a bicycle is a function of the friction between the brake surfaces. To make
sure that you have maximum friction available, keep your wheel rims and brake pads or the disc
rotor and caliper clean and free of dirt, lubricants, waxes or polishes.
Brakes are designed to control your speed, not just to stop the bike. Maximum braking force for
each wheel occurs at the point just before the wheel “locks up” (stops rotating) and starts to skid.
Once the tire skids, you actually lose most of your stopping force and all directional control. You
need to practice slowing and stopping smoothly without locking up a wheel. The technique is
called progressive brake modulation. Instead of jerking the brake lever to the position where you
think you’ll generate appropriate braking force, squeeze the lever, progressively increasing the
braking force. If you feel the wheel begin to lock up, release pressure just a little to keep the wheel
rotating just short of lockup. It’s important to develop a feel for the amount of brake lever pressure
required for each wheel at different speeds and on different surfaces. To better understand this,
experiment a little by walking your bike and applying different amounts of pressure to each brake
lever, until the wheel locks.
When you apply one or both brakes, the bike begins to slow, but your body wants to continue at
the speed at which it was going. This causes a transfer of weight to the front wheel (or, under
heavy braking, around the front wheel hub, which could send you flying over the handlebars).
A wheel with more weight on it will accept greater brake pressure before lockup; a wheel with
less weight will lock up with less brake pressure. So, as you apply brakes and your weight is
transferred forward, you need to shift your body toward the rear of the bike, to transfer weight
back on to the rear wheel; and at the same time, you need to both decrease rear braking and
increase front braking force. This is even more important on descents, because descents shift
weight forward.
Two keys to effective speed control and safe stopping are controlling wheel lockup and
weight transfer. This weight transfer is even more pronounced if your bike has a front
suspension fork. Front suspension “dips” under braking, increasing the weight transfer (see
also Section 4.F). Practice braking and weight transfer techniques where there is no traffic
or other hazards and distractions.
Everything changes when you ride on loose surfaces or in wet weather. Tire adhesion is reduced,
so the wheels have less cornering and braking traction and can lock up with less brake force.
Moisture or dirt on the brake pads reduces their ability to grip. The way to maintain control on
loose or wet surfaces is to go more slowly to begin with.
D. Shifting Gears
Your multi-speed bicycle will have a derailleur drivetrain (see 1. below), an internal gear hub
drivetrain (see 2. below) or, in some special cases, a combination of the two.
1. How A Derailleur Drivetrain Works
If your bicycle has a derailleur drivetrain, the gear-changing mechanism will have:
• a rear cassette or freewheel sprocket cluster
• a rear derailleur
• usually a front derailleur
• one or two shifters
• one, two or three front sprockets called chainrings
• a drive chain
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