2. How brakes work
The braking action of a b icycle is a fu nction of the fricti on bet ween th e brakin g surfa ces. To make sure that
you have
maximum friction available, keep your wheel rims and brake pads or the disk rotor and caliper clean and free of dirt, l ubricants,
or waxes polishes. Brakes are designed to control your speed, not just to stop the bike. Maximum brak ing force for ea ch 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 appro
priate 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 req uired for each wheel at dif ferent spee ds and on dif ferent surfaces. To better under stand 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 bik e begins to slow, but your body wants to continue at the spee d at which it was
going. T
his 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 pressur e
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 th e rear wheel; and at the same time, y ou need to both decreas e rear brakin g 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 a lso Section 4.F). Practice bra king and weight transfer techniques where there is no tra ffic or other ha zards and
distractions.
Everything changes when you ride on loose surfaces or in wet weather. It will take longer to stop on loose surfaces or in wet
weath
er. 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.
D. Shifting gears
Your multi-speed bicycle will have a der ailleur drivetrain (see 1. belo w), an internal gear hub drivetrain (see 2. belo w) or, in
some special cases, a combination of the two.
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