Passage IV

Two types of friction affecting bicycle riders are:

· air resistance

· rolling resistance between the tires and the ground

Table 1 gives the air resistance, R_A, affecting a rider moving at speed V when the cross-sectional area of the rider plus bicycle equaled X. Table 1 also gives the power, P_A, in watts (W), the rider had to generate to compensate for R_A to maintain V. Figure 1 gives the power, P_{A + R}, in horsepower (hp), a rider had to generate to compensate for R_A plus rolling resistance to maintain V = 5.6 m/sec or 11. 2 m/sec for a wheel diameter of 16 inches or 27 inches and various tire pressures. Figure 2 is a graph of power in W versus power in hp.

Figure 1 adapted from Frank Roland Whitt and David Gordon Wilson, "Bicycling Science." @1974 by The Massachusetts institute of Technology.