Patent ID: 7153229

Claim:
A chain alignment structure for a bicycle transmission, comprising: a drive sprocket wheel, said drive sprocket wheel being rotatably drivable by a crankshaft; a driven sprocket wheel, said driven sprocket wheel being drivably connectable with an output shaft that is rotated in an interlocking manner with a drive wheel of the bicycle; and an endless chain, said endless chain being wound around the drive sprocket wheel and the driven sprocket wheel, wherein a chain guide member is arranged on an endless-chain-reel-in side of the drive sprocket wheels, wherein the chain guide member includes an upper guide portion arranged above a path of the endless chain, a lower guide portion arranged below the chain path, a vertical connecting portion that connects the upper guide portion and the lower guide portion together, and a throat portion allowing the chain to pass through to the drive sprocket wheel, and wherein the upper guide portion includes a first guide portion that is substantially parallel with the lower guide portion and includes a second guide portion extending downwards toward the lower guide portion such that when the endless chain is slackened, the endless chain abuts against the second guide portion and is aligned in a straight line at the throat portion of the chain guide member so as to be enter the drive sprocket wheel.