Originally Posted by USCF Rulebook

1J. Bicycles
1J1. Bicycles used in competition must be propelled solely by the rider's legs and shall have the following characteristics:
(a) Dimensions. Bicycles may be no more than 2 meters long and 75 cm wide, except that tandems may be up to 3 meters long
(b) There may be no protective shield, fairing, or other device on any part of the bicycle, which has the effect of reducing air resistance except that spoke covers may be used
(c) Wheels may be made with spokes or solid construction. No wheel may contain special mechanisms to store and release energy