Question

Question: While reducing the mass of a racing bike, the greatest benefit is realized from reducing the mass of the tires and wheel rims. Why does this allow a racer to achieve greater accelerations than would an identical reduction in the mass of the bicycle’s frame?

Short answer

Greater acceleration in bicycle can be achieved by reducing the mass of tires and rims.

Step-by-step solution

Concept of moment of inertia with reduced mass of tires and wheel rims in bikes.

Moment of inertia is obtained by the addition of the product of mass and the distance squared for all the masses comprising the body.

In racing bike, wheels are the rotating parts not the frame of the bike. By reducing the mass of tires and the wheel rims, its moment of inertia gets reduced.

The moment of inertia of wheel rim is given by,

$I=M{R}^2$

Here, M is the mass of tire and the rim together and R is the distance between the wheel axle to the rim.

Reason for greater acceleration in bicycle with reduced mass of the tires and wheel rim.

Work done during cycling is used in the rotational energy of the tires and rim. When the mass of tires and rims is reduced, higher velocities can be achieved with less work. This achievement of high velocities means high acceleration.