The function of this invention is to provide exercisers with a safe and easy way to convert a legs-only exercising device, such as a stationary trainer or bicycle, with the capacity to exercise their upper and lower body muscle groups simultaneously or separately. This invention is portable and can be moved easily from one legs-only exercising device to another. Once they are mounted onto the handlebar or attachment bar of the legs-only device, it is now a full-body trainer. Exercisers mount the trainer, place their feet on the cycling pedals, place their elbows onto the elbow holders, grasp the hand grips, and now start their full body exercising activity. The degree of difficulty of their exercise trek is easily accommodated by allowing the rider to adjust the resistance for moving the forearm bars up and down for an upright bike, or back and forth for a recumbent trainer.

A bicycle includes a suspension system of the rear wheel, a crankset integral with the frame, and a hub and pinions assembly integral with the rear wheel, which are subjected to reciprocal displacement by the action of the suspension system. The crankset and the hub and pinions assembly each include at least one gear wheel engaged by the chain and a rotation shaft. Between the gear wheel and the shaft, there is operatively interposed a compensation device placed to allow a compensation angular stroke between them from a rest position corresponding to an absence of chain pull, to a compensation position, corresponding to an action of chain pull generated by the reciprocal displacement, and vice versa. The compensation device includes an adjustment system of the compensation angular stroke.