The values in Table III are in line with CD and CR values reported by Lim et al.9 The value of CR must be between zero and tan θ = 0.035; otherwise, the bicycle would not begin to roll in an experiment with zero initial speed. The large uncertainty on CR is related to the uncertainty on the slope angle θ (Δθ = 0.3°) because the fitting procedure only provides a value for sin θ − R cos θ. But what clearly can be seen is that the rolling resistance increases in the case of underinflated tires. The larger cross section has, within the obtained accuracy, no influence on CR. To graphically illustrate the forces that act on the cyclist along the stretch, the rolling resistance
and the air drag are plotted in Fig. 4 as a function of speed for
the three experiments in Table III.