Bike driving device

A bike driving device mainly comprises a frame (3), a speed changing box (18), a rear driving wheel (15) installed on an output shaft of the speed changing box, an overrun clutch (37) installed on an input shaft of the speed changing box, and driving device bodies installed on the frame (3). The bike driving device is characterized in that the driving device further comprises connecting rod transmission pieces (10) used for being connected with driving connecting rods (7); two driving device bodies are installed on the two sides of the part, between the part, with each pedal (1), of the frame (3) and the speed changing box (18) respectively, other structures are arranged, and when a user stands on the two pedals of the bike to conduct treading, the four driving device bodies on the two sides of the pedals can be driven simultaneously. Thus, the defects that in the prior art, a driving connecting rod of a bike with the Chinese patent number 201420590209.3 is of a single-edge single-strip structure, and consequently when a user treads the pedals for driving, due to the single-edge stress in the pulling of the driving connecting rod, the overrun clutch is uneven in stress, prone to fracturing, very poor in durability and the like are overcome; thus, the overrun clutch of the bike driving device is even in stress, capable of avoiding fracturing and very durable, treading is very light and stable, and much effort is saved.