To provide a vehicle with a trailer and a bicycle having a one-way transmission part, allowing the trailer to be easily connected to the bicycle.

A vehicle 10 includes a bicycle 12 and a trailer 14. The bicycle 12 includes a frame 16, a front wheel 44, rear wheels 56, 58, a regulation device 146, a crank 178, and braking devices 204a, 204b. The trailer 14 is connected to the frame 16. The front wheel 44, rear wheels 56, 58 and crank 178 are supported by the frame 16. The crank 178 and rear wheel 56 are connected to each other through a transmission mechanism T including a one-way clutch 186. The transmission mechanism T transmits forward rotation of the crank 178 to the rear wheel 56, while the forward rotation of the rear wheel 56 is not transmitted to the crank 178. The braking devices 204a, 204b brake the rear wheels 56, 58. The regulation device 146 is provided independently from the braking devices 204a, 204b to regulate rotation of the rear wheels 56, 58.