New UCI rules to address follow cars and Hour Record prototype frames

Cycling's governing body puts aerodynamic advantage and marginal gains under scrutiny with new regulations.

by Ronan Mc Laughlin

photography by CorVos


The UCI has updated its technical regulations in a bid to reduce the aerodynamic aid of following vehicles on a rider in individual time trials. While cyclists instinctively know of the benefits of following another rider or vehicle, it is only relatively recently that riders and teams have become aware of the aero benefits presented by both riders and vehicles behind a rider.

The issue came to greater public awareness earlier this year when the new World Hour Record holder Filippo Ganna’s following car in the Tirreno Adriatico time trial was pictured with as many as ten spare bikes on the roof, following closely behind the then-world time trial champion. While the tactic of “pushing” a rider with a gust of wind from an accelerating following car has long played a role in professional time trialling, it is only recently that aerodynamicists discovered the pressure-reducing effect the following car offers in helping a rider move faster.

This marginal gain touched a nerve with many spectators and the UCI alike, and the world governing body has now moved to restrict this effect as of January 1 2023 in an update published on September 23. While the number of spare bikes permitted on the roof of following cars has not been restricted, the UCI amended the regulations to mandate following cars must now stay a minimum of 15 m behind the rider, an increase of 5 m over the 10 m previously in effect.

The following vehicle shall follow at least 10 15 meters behind the rider, shall never overtake him nor draw up level with him. In the case of a breakdown, technical support may be rendered only with the rider and vehicle stationary and the following vehicle shall not hinder anyone else.

Chapter IV Individual time trials, 2.4.023: Following vehicles

Big deal?

How much difference can the following car make? A study conducted by Bert Blocken and the Eindhoven University of Technology (TU/e) suggest it’s quite significant, with 3.7%, 1.4%, and 0.2% for cars following at 3, 5 and 10 m. Over a 50 km time trial, the study says these three scenarios could save the rider as much as 62.4 s, 24.1 s and 3.9 s versus no car. Professor Blocken has been calling for a 30 m minimum following distance since the study was first published in 2015.

Regardless of the exact distance stated in the regulations, the rule change will only prove effective if the UCI actually enforces it. Only time will tell if that happens.

No more prototype records

In a further update released just last week, the UCI has also moved to prohibit the use of prototype frames in Hour Record attempts.

Currently, the regulations state, “any equipment in development phase and not yet available for purchase (prototype) must be subject of an authorisation request to the UCI Equipment Unit before its use.” The UCI has now restricted prototype use with an amendment set to come into effect as of January 1. The regulations update now states, “use of equipment under prototype authorisation in track events and/or in the context of a particular performance (best performance, world record, hour record or other) shall not be authorised.”

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