Abstract: An air pump for use with a chain-driven bicycle having a free wheel. The pump assembly comprises a pair of opposed cylinders and a double-ended piston rod mounted in a housing. The piston rod has a bearing slot, which engages a crank pin on a crankshaft driven by a sprocket. Rotation of the sprocket reciprocates the double-ended piston rod in the cylinders. The cylinders are each integrally formed with a manifold that uses an elastomeric band covering a passage from the cylinder interior to inside the manifold as a one-way valve. An enlarged diameter skirt on each cylinder allows air to enter the cylinder on each intake stroke. A cap defining the piston head is locked onto each piston and holds a seal in place on the piston. An integral clamp assembly allows the pump to be removably mounted on a bicycle chain stay. The lower run of the bicycle drive chain engages the drive sprocket of the pump assembly, and a chain retainer is used to maintain the engagement of the drive chain with the drive sprocket.

Abstract: An air pump for use with a chain-driven bicycle having a free wheel. The pump assembly comprises a pair of opposed cylinders and a double-ended piston rod mounted in a housing. The piston rod has a bearing slot, which engages a crank pin on a crankshaft driven by a sprocket. Rotation of the sprocket reciprocates the double-ended piston rod in the cylinders. The cylinders are each integrally formed with a manifold that uses an elastomeric band covering a passage from the cylinder interior to inside the manifold as a one-way valve. An enlarged diameter skirt on each cylinder allows air to enter the cylinder on each intake stroke. A cap defining the piston head is locked onto each piston and holds a seal in place on the piston. An integral clamp assembly allows the pump to be removably mounted on a bicycle chain stay. The lower run of the bicycle drive chain engages the drive sprocket of the pump assembly, and a chain retainer is used to maintain the engagement of the drive chain with the drive sprocket.

Abstract: An air pump for use with a chain-driven bicycle having a freewheel. The pump assembly comprises a pair of opposed cylinders and a double-ended piston rod mounted in a housing. The piston rod has a bearing slot which engages a crank pin on a crankshaft which is driven by a sprocket. Rotation of the sprocket reciprocates the double-ended piston rod in the cylinders. A hook-shaped extension of the housing fits over the top of the chain stay of the bicycle, and a vertically movable clamping member provided with a ratchet mechanism abuts the underside of the chain stay; a lever operated cam clamps the chain stay intermediate the hook portion and the clamping member. The lower run of the bicycle drive chain engages the drive sprocket of the pump assembly. Reverse rotation of the bicycle's crank assembly causes the conventional freewheel to also rotate in a reverse direction without rotating the wheel of the bicycle.