Physilab bicycle ergo graph a bicycle frame is supported by a wooden stand, from the front of which two uprights ascend and carry a desk and cross piece, which provide for the attachment, directly in front of the subject, of the tension balances and other pieces in front of the subject, of the tension balances and other pieces of apparatus. A cast iron wheel of 5 1/2 feet in circumference, weighing 22 kilos and mounted on ball bearing, is substituted for the back wheel. This wheel has slightly beveled edges and is turned true. To the circumference of this, a stout calico is applied, and the two ends of the band ate attached to spring balances of 6 lbs. Range (graduated in one oz. ) calico-band to the balance pass round adjustable pulleys in order to give them the right direction. An adjustable record counter records the revolution of the wheel.