Racing cyclists get aero benefit from a motorcycle behind them, says scientific study

A motorcyclist following a racing cyclist can assist the rider in reducing their air resistance by up to nine per cent, a new scientific study has concluded.

Researchers at the University of Technology Eindhoven, University of Leuven and University of Liege have said that this can give a rider a significant advantage during an individual time trial. "Evidence suggests that the effect is much greater than previously thought," they report.

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Using scale models of a cyclist in a time trial position and a motorbike with two riders on board in a wind tunnel, the researchers measured the aerodynamics at various distances apart.

They also used computer modelling to determine the effect of a following motorbike on the air pressure around the cyclist in front.

Motorbikes with two riders on board are commonly used for TV cameras, in-race photographers and race support.

At a distance of 25 centimetres behind the cyclist, the motorbike could cut the rider's air resistance by nine per cent. If there were three following motorbikes, this was measured as 14 per cent.

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"Race pictures suggest that such short distances are certainly not uncommon in elite races," said the researchers.

Using this Friday's opening Giro d'Italia 9.8-kilometre time trial in Apeldoorn as an example, the study concluded that a rider with a following motorcycle could gain several seconds. Enough of a margin to have a significant effect on the rider's overall position.

One area missing from the summary of the research published online is whether a cyclist, rather than motorbike, following a cyclist would have any effect on the speed of a rider in front.

Previously, research by University of Technology Eindhoven showed that a following car can also give a cyclist a significant advantage.

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The researchers have appealed to the Union Cycliste Internationale (UCI) to increase the minimum allowed distance between a rider and a following motorcycle to 30 metres.

The report also noted the recent incidents involving race motorbikes in causing injuries to riders, adding weight to an argument to increase the distance between cyclists and motorbikes.