UCI CYCLING REGULATIONS  16.16.010  In road races, a tricycle with two rear wheels shall be fitted with a safety bar to prevent  the front wheel of a following tricycle from entering the space between the rear wheels.  The safety bar must be well fixed to the tricycle so that there is no risk of the bar moving  during competition. The distance from the ground to the centre of the safety bar should  be the same as the distance between the ground and the middle of the hub when the  tires are inflated to the pressure used in competition. The safety bar must not exceed the  width of each rear wheel tire and all tube ends closed or plugged. The safety bar must  be fitted 15 mm (+/- 2 mm) behind the wheels. It must be a round tube of at least 18 mm  in diameters, made of adequate solid material. Both tube ends must be plugged (see  drawing).  (text modified on 01.01.09; 01.01.10; 01.01.17)  E0121  PARA-CYCLING  72 