Starting times are at equal intervals, usually one or two minutes apart. The starting sequence is usually based on the finishing times in preceding races (or preceding stages in the case of a multi-stage race) in reverse order of the competitors placing (with the highest ranked cyclist starting last). Starting later gives the racer the advantage of knowing what time they need to beat (and also makes the event more interesting to spectators). Competitors are not permitted to 'draft' (ride in the slipstream) behind each other. Any help between riders is forbidden. The rider with the fastest time is declared the winner.
At the professional level, time trials (TTs) are frequently accompanied by motorcycles, some carrying video equipment or race officials, and riders may be followed by a team car carrying coaches and spare parts, but the cyclists are not permitted to draft behind the vehicles. Race regulations typically dictate a minimum distance behind the cyclist which the car must maintain and a minimum gap that must exist between two cyclists before the car may enter that gap.
For many years in the UK, time trials were the main road-based cycling competitions ('massed start' events only gained grudging approval after the Second World War). Even today, TTs are usually held over a specified course of fixed distance, 10, 25, 50 and 100 miles being common. TTs can also be held over or a fixed time (12 and 24 hours being common). If a racer catches up to a competitor, the overtaken rider is required to fall back to a specified distance (about 50 metres) behind the other so that he receives no aerodynamic shelter or help from the other.
To do well in an ITT, a cyclist must