Filippo Ganna claimed victory on the opening stage TT at Tirreno Adriatico yesterday, though some cycling fans watching the race on TV pointed to the very large number of bikes on the roof rack of the car following the Italian.
While the affects of drafting from a vehicle ahead is well understood in cycling, the impact a following vehicle can have has not been thrashed out as much publicly.
However, the first study conducted on the subject suggests a following vehicle can reduce drag, helping the cyclist to cut through the air much more easily, thus increasing their speed and TT times.
The rule of thumb is that the bigger the following vehicle is, the bigger the benefit will be for the rider.
And so a car with a roof rack packed with spare bikes effectively increases the size of the following vehicle, thus aiding the rider even more. The practice is not illegal, by the way.
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To be fair to Ganna and his Ineos Grenadiers team, they were not the only ones who stacked the roof racks of the team car following their best TT riders yesterday. Remco Evenepoel was 2nd in the 13.9km flat TT in Lido di Camaiore, 11 seconds down on Ganna, and his Quick-Step Alpha Vinyl team also used a team car following him that was stacked with spare bikes on the roof.
Tadej Pogačar (UAE Team Emirates) was 3rd in the test, at 18 seconds, and the team car following him had just one bike – a single TT machine ready to be given up to the Slovenian in the event of a puncture or crash. The BikeExchange-Jayco team car following Italian TT champion Matteo Sobrero was also notably packed with bikes - he was 10th at 39 seconds.
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Dutch engineer Bert Blocken, who has studied aerodynamics in cycling, pointed out the only research he was aware of on the impact of following vehicles, and which he himself conducted in wind tunnels, suggested there were very significant gains to be made.
Those gains, from the drag reduction created by the following vehicle, were the biggest when larger following vehicles were used and when those cars were driven very closely behind the rider.
“The drag reduction for the cyclist ranges from 3.7 per cent over 1.4 per cent to 0.2 per cent for realistic separation distances of 3, 5 and 10m, respectively,” that study concluded.
“For a typical 50 km individual time trial, the potential time reduction by exploiting this effect (e.g. by a car following the rider at this short distance versus no car behind) is 62.4 s, 24.1 s and 3.9 s, respectively. As elite cyclist time trials are often won based on seconds or sometimes even less, these differences can be decisive for who wins the stage.
“Therefore, it is recommended that the UCI not only raises its current minimum separation distance of 10 m to at least 30 m, but also strictly enforces it, to avoid this unwanted aerodynamic effect that can influence the outcome of the race.”
If you want to read more on that study, from 2015, you can find it by following this link.
