Auxiliary power device of bicycle

[0015]As shown in FIG. 1, a bicycle 1 of the first preferred embodiment of the present invention includes a frame 10 having a front fork 12, a rear fork 14, and two wheels 16, 18 pivoted on the front fork 12 and the rear fork 14 respectively. The frame 10 further includes a handle bar 20 connecting the front fork 12, a seat 22, a crank 24, and a transmission assembly 26 including a front gear set connecting the crank 24, a rear gear set on the rear wheel 18, and a chain connecting the front gear set and the rear gear set. The aforesaid elements are as same as the conventional bicycle, so we do not describe the detail here.

[0016]The frame 10 includes a first section 28 and a second section 30. A cushion 32 is provided between the first section 28 and the second section 30 that the first section 28 and the second section 30 will have a relative motion therebetween in cycling. The present invention uses such relative motion between the first section 28 and the second section 30 to generat