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Race motorbikes can give cyclists 48% less drag, new research shows

True effect of race motorbikes uncovered in latest research from the Netherlands

Joe Robinson
28 Jun 2019

New research from Eindhoven University has worked out just how much help a cyclist can get by riding behind a motorbike. The analysis found that a cyclist would experience 48 per cent less drag while riding 2.5 metres behind a motorbike.

If that cyclist was travelling at 54kmh without a motorcycle, the presence of the motorcycle would allow the cyclist to travel at a staggering 67kmh for the same effort. Over a minute, this would also translate to 14.1 seconds gained.

Even when the motorbike is not as close, there is still a tangible effect. A cyclist riding at 30m behind a motorbike will still experience 12 per cent less drag which is around 2.6 seconds every minute.

Increase the distance to 50m and cyclists will still receive a 7 per cent reduction in drag, at around 1.4 seconds over a minute.

Lead professor on this investigation Bert Blocken believes that these figures reveal the true effect a motorcycle can have on a professional bike race.

'Even if a motorcyclist only rides for a few seconds in front of the riders, a considerable time advantage can still be gained. For a rider cycling for 10 seconds at 2.5 metres behind a motorcycle, this gain can exceed 2 seconds,' said Blocken.

'We repeated the wind tunnel measurements and our calculations a few weeks after the first tests because I couldn’t believe the size of the effects. But we always found the same results.

'Because races are sometimes decided by seconds, these differences can determine whether you win or lose. The often-heard complaint that motorcycles can influence the outcome of races is therefore justified.'

The study also contained a comment from performance director Dr Fred Grappe of French WorldTour team Groupama-FDJ

Grappe stated that it is 'necessary to define a kind of "free zone" around the rider in which no motor vehicle is allowed for more than a few seconds.

He went on to say that, 'Bert Blocken's new scientific study in cycling dynamics provides the knowledge to determine such a zone effectively. Given the influence of even a few seconds on a ranking, it is unacceptable to ignore this knowledge and its importance.'

The effect of motorcycles on a professional bike race has been a persistent issue although particularly pertinent in the past few seasons.

The UCI introduced stricter rules in 2017 to reduce the number of vehicles and their access to the race after a series of unfortunate incidents with riders.

At last year's Tour de France, Bahrain-Merida attempted to take race organisers ASO to court after its team leader Vincenzo Nibali fractured vertebrae after colliding with a race motorbike.

In 2017, Geraint Thomas was forced to abandon the Giro d'Italia after colliding with a police motorbike on Stage 9 to Blockhaus.

More recently, some observers claimed that Mathieu van der Poel's heroic victory at Amstel Gold was aided by the number of race motorbikes that rode in front of him in the closing stages of the race.

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