Friday, July 12, 2013

Time trial position: Anquetil versus Martin

L'Equipe recently posted a nice article on the history of time trialing, including the hour record. The posting included a wonderful photo of Jacques Anquetil, an unsurpassed time trialer in the history of professional bike racing. Jacques' peak was the late 1950's and early 1960's. He won the Tour 5 times, perhaps with the assistance of blood transfusions in the later years.

Anquetil was famous for his extreme toe-down pedal style. It's typically recommended the foot at the bottom of the pedal stroke be at a relatively shallow angle, for example 15 degrees. But Anquetil's foot was at a much steeper angle: closer to 45 degrees. It's hard to argue this approach slowed him down at all, but I've not seen it imitated by accomplished racers.

The dominant time trialist of today amomg the ProTour ranks is clearly Tony Martin. His most recent victory is the first individual time trial in the 2013 Tour de France, which is ongoing as I write this. Despite having suffered appalling road rash on his back in a crash in the Tour's opening stage in Corsica, he was able to beat yellow jersey Chris Froome in the time trial, Froome by far the fastest among the general classification contenders.

Riders today have access to sophisticated wind tunnel and field testing to optimize their positions on the bike. The position of aero bars is tuned to the millimeter, with subtle differences in hand and arm position assessed for their influence on drag. Racers such as Martin spend hundreds of hours on their time trial bikes each season, acclimating themselves to the position so they can reach the full potential of their cardiovascular systems in generating power while aerodynamically optimized.

Anquetil, on the other hand, had access to none of this. Until the mid 1980's, time trials were contested on a similar bike with a similar position used in mass-start road races. The equipment focus on the bike was on everything except wind resistance: minimizing the weight, using the lightest oil in the bearings, and using thin tires pumped to the highest pressures.

You might think the rider positions would be night and day between Anquetil and Martin, the latter having access to more than a half century of technological advances. To check this, I overlaid an image of Martin similar to the Anquetil image with Gimp. I scaled the Anquetil image to match the outside diameters of the front tires, since these are similar. I then superposed the front tires. I then rotated each image so the line tangent to the top of the two tires was horizontal.

This approach is good, but it's still subject to perspective distortion since the positions of the cameras relative to the two riders isn't perfectly matched. So it's not consistent with a high degree of precision. But the result is interesting:

The similarity of the positions might be surprising.

First, consider the bikes. Anquetil's wheelbase is longer, especially due to longer chainstays That was the style then: due to relatively rough roads, the chainstays were kept long to reduce vibrations. Additionally, the front fork was dramatically raked to act as a spring, reducing vibrations at the front as well.

An additional feature of the bike is a remarkable lack of handlebar drop by modern pro cyclist standards. This is because racers in Anquetil's day used the drops for a "racing" position, while today the hoods are more commonly used since that's where the shifters are now. Despite the lack of drop, he has no problem adopting a position with the top of his head below the peak of his back. He looks at least as aero as Martin.

Could Anquetil's position be tweaked with wind-tunnel analysis? No doubt. But despite the drastically different bicycles, it's more similar than different.

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