Patent ID: 7029424

Claim:
An exercise bicycle having a modular transmission assembly, the modular transmission assembly comprising: a hollow housing having two open ends; a drive wheel connected to an exercise input structure, said drive wheel being rotatably mounted on one external side of the hollow housing; an idler wheel rotatably mounted in the hollow housing and having a large portion thereof protruding out of the hollow housing; a belt mounted around the drive wheel and a shaft extending out from the idler wheel to allow rotation of the drive wheel to drive the idler wheel to rotate accordingly; a tension rod pivotally connected to the hollow housing on the external side the same as that to which the drive wheel is fitted and having a first end abutted to a portion of the belt and a second end securely connected to a first end of a first spring, a second end of which is securely connected to a side face of the hollow housing, such that the first end of the tension rod is maintained in abutment with the belt; and a resistance device adjustably mounted on the hollow housing to provide different resistances to the idler wheel such that when the drive wheel is rotated, a force to drive the drive wheel to rotate is dependent on the resistance applied to the idler wheel, wherein the first end of the tension rod is provided with a bearing to abut the portion of the belt, wherein the resistance device comprises: an arcuate plate having a curvature substantially the same as that of the idler wheel, a first end securely connected to a side face of the hollow housing and a second end formed with a wall; and a threaded bolt threadingly extending through the wall to abut a side face of the hollow housing such that a distance between the arcuate plate and the idler wheel is adjustable.