Adjustable bicycle frame

The invention provides an adjustable bicycle frame which comprises a front tube, a saddle tube, a rear fork, a beam and a saddle. The beam comprises a first beam body and a second beam body. A first side lug and a second side lug are arranged on the front tube. The saddle tube is fixed between the first beam body and the second beam body through a fastener on a fixing device. The end, close to the front tube, of the first beam body and the end, close to the front tube, of the second beam body are each provided with a groove. The first side lug and the second side lug are erected into the groove in the first beam body and the groove in the second beam body respectively. An adjusting component is arranged on the rear fork. A plurality of adjusting holes are formed in the adjusting component. The rear fork is erected between the first beam body and the second beam body through the adjusting holes. A positioning stand column is arranged at the bottom of the saddle, can move inside the saddle tube and is fixed through the fastener. The adjustable bicycle frame has the advantages that the front tube, the beam, the saddle tube, the saddle and the rear fork are detachably connected, the connecting positions can be adjusted, no welding points exist on the whole frame, and functions are added.