1) The tandem bicycle is a vehicle for two riders, with two wheels of equal diameter, which conforms to the general principles of UCI construction for bicycles. The front wheel shall be steerable by the front rider, known as the ‘pilot’. The guide shall be the front rider and the TRI 6 competitor will ride in the rear. Both riders shall face forward in the traditional cycling position and the rear wheel shall be driven by both cyclists through a system comprising pedals and chains. 2) The tandem top tube, and any additional strengthening tubes, may slope to suit the morphological sizes of the riders.