A stretching bicycle comprises a front frame section having a hollow front bar as a portion of crossbar, a rear frame section having a hollow rear bar for slidably receiving the front bar, the front and rear bars being disposed in a straight line not aligned with the front and rear wheels, and fastening means for securing the front and rear bars together at a front opening and a rear opening of the rear bar respectively. The bicycle has the advantages of adjusting length for accommodating users of different body heights in use, saving storage space after disassembly, and being structurally strong and lightweight.