In the sport of
mountain biking you experience both accelerations and decelerations. This
is what makes mountain biking so exciting, but it also the reason why you
should always wear a helmet! Acceleration is defined as a change in velocity
divided by a given amount of time. A rider accelerates as he or she exerts
energy and starts to pedal, but can also accelerate as he or she rides down
a hill, and this acceleration is due to the force of gravity mentioned earlier.
As you accelerate, the weight of the wheels affects the acceleration process
three times as much as the weight of the bike and its rider. So one pound
in a wheel feels and behaves more like three pounds. This explains the reason
why wheels and tires are made as light as possible. Once the rider eventually
coasts to a stop or applies the brakes, he or she experiences a deceleration.
This deceleration is what causes the bumps and bruises a mountain biker
is bound to get as they ride and eventually crash.