Chris Froome’s curious descending position isn’t as aerodynamically efficient as he might hope, according to new research from the Netherlands and Belgium.
Researchers led by Bert Blocken of the Eindhoven University of Technology in the Netherlands and KU Leuven (Leuven University) in Belgium investigated the aerodynamic performance of different descending positions in cycling, looking particularly at the positions of Chris Froome, the late Marco Pantani, Fabian Cancellara, Peter Sagan and two different positions adopted by Vincenzo Nibali.
Let’s cut to the chase here: Peter Sagan’s position – sitting down on the top tube, but pushed further back than Chris Froome’s position – comes out on top, based on the assumption that none of the cyclists in these positions would be pedalling, or they’d all be pedalling with the same power output.
Here are the results in full:
Pic courtesy of Bert Blocken, Eindhoven University of Technology, the Netherlands and KU Leuven, Belgium
Fabian Cancellara’s ‘back upwards’ position came out slowest with Nibali’s ‘back horizontal’ position 8% faster. Froome’s position was 9% faster than Cancellara’s, Nibali’s ‘back down’ position was 12% faster, while Pantani’s position, resting his chest on the saddle with his bum just over the back wheel, was 14% faster.
Sagan’s ‘top tube safe’ position, sitting on the top tube with his chest on the stem so that his weight is distributed quite evenly over the wheels, was calculated to be 17% faster than Cancellara’s.
How did Professor Blocken and his team work this out?
First, through wind-tunnel testing. They scanned a cyclist in different positions, had models made at 1:4 scale and tested those models in the wind tunnel in Liège.
Then the team used computational fluid dynamics (CFD) simulations with extremely high-resolution models (36 million calculation cells).
The researchers acknowledge that it’s a crude calculation but say that Sagan’s ‘top tube safe’ position could have saved Froome 1:07mins over the position he actually used when he attacked on the Peyresourde descent on Stage 8 of last year’s Tour de France (he might not care; he won the race anyway). As well as being faster, the researchers believe that the top tube safe’ position is less risky – hence the name, obviously!
Froome’s position does have an advantage over the ‘top tube safe’ position in that it allows pedalling but not, the researchers say, with a large power output.
Interestingly, the so-called ‘Superman’ position (above), where a rider essentially lies forward on the bike with his torso on the saddle and legs stretched out behind him/her (not to be confused with Graeme Obree’s Superman position which was entirely different), was found to be 24% faster than Cancellara’s base time… But if you want to ride down the Peyresourde like that, well, you’re on your own.
As an aside, Peter Sagan Tweeted today that he was working on his aero position in California, so you can expect to see it making another appearance in one of the big races soon.
— Peter Sagan (@petosagan) May 9, 2017
Mat has been in cycling media since 1996, on titles including BikeRadar, Total Bike, Total Mountain Bike, What Mountain Bike and Mountain Biking UK, and he has been editor of 220 Triathlon and Cycling Plus. Mat has been road.cc technical editor for over a decade, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a winner of the Cycling Media Award for Specialist Online Writer. Now over 50, he's riding road and gravel bikes most days for fun and fitness rather than training for competitions.