Patent ID: 7243936

Claim:
A foldable bicycle frame comprising a top tube having a front top tube with a rear coupling end and a rear top tube with a front coupling end, a head tube at a front side of said top tube, a seat tube at a rear side of said top tube, and a rear fork assembly obliquely backwardly extending from said seat tube opposite to said top tube, and a folding structure connected between the rear coupling end of said front top tube and the front coupling end of said rear top tube, wherein said folding structure comprises: a top connecting bar and a bottom connecting bar arranged in parallel at top and bottom sides of said front top tube and said rear top tube and respectively pivotally coupled to rear coupling end of said front top tube and the front coupling end of said rear top tube to join said front top tube and said rear top tube and respectively vertically movable relative to said front top tube and said rear top tube between a first position wherein said top connecting bar and said bottom connecting bar are respectively engaged with said front top tube and said rear top tube at top and bottom sides to prohibit relative movement between said front top tube and said rear top tub, and a second position where said top connecting bar and said bottom connecting bar are disengaged from said front top tube and said rear top tube for allowing said front top tube and said rear top tube to be turned relative to each other; at least one spring stopped between said top connecting bar and said bottom connecting bar for holding said top connecting bar and said bottom connecting bar in said second position; and a locking mechanism having at least one axle mounted in said top connecting bar and said bottom connecting bar, and at least one operating member provided at one end of said axle and turnable relative to said axle between a locking position to lock said top connecting bar and said bottom connecting bar in said first position, and an unlocking position to unlock said top connecting bar and said bottom connecting bar for enabling said top connecting bar and said bottom connecting bar to be moved by said spring to said second position.