Sunday, July 10, 2011

Specialized Venge and Mark Cavendish

The Specialized Venge made its debut at Milan San Remo this year, and it couldn't have gone any better for the Morgan Hill company, as Matt Goss, a relative underdog, won the race. Move on the Tour de France, and with aerodynamically optimized mass-start road frames more popular than ever, Mark Cavendish has pulled out two impressive sprint victories on the bike in a first week notably unfavorable to sprinters. Last year when HTC was sponsored by Scott instead of Specialized, Cavendish rejected his Scott Foil (then F01) in favor of his tried-and-true super-beefed-up Addict, so once again this looks good for Specialized.


Venge spotted at Mike's Bikes in San Francisco


But the frame is only a relatively small part of the aerodynamic picture. Far more important is body position. So here's photos of Cavendish during his two victories this year... first stage 5:

CyclingNews
CyclingNews


Then stage 7:

CyclingNews
CyclingNews


These photos aren't cherry-picked: they're the first ones I found on CyclingNews of the respective sprints in the final 100 meters or so. Just look at Cav's position: the top of his helmet is hardly higher than his back. Sure, some other riders can be seen with low head positions, but that's with their faces down, not sustainable. Cavendish is always looking forward, never down. He's watching where he's going.

Here's a shot from Mark in 2009 outsprinting Thor Hoshovd, Oscar Friere, and a Milram rider (Ciolek, I believe). Look how vastly superior his position is to his competitors:
2009 Tour de France
Associated Press


It's often said sprinting is about raw power. Yet Cavendish's power is easily overestimated. It's been reported that Cavendish doesn't "test" well, and that in sprints he produces only around 1300 watts, a non-spectacular number. Of course, he's producing that power at the end of a long difficult race, after finishing with several kilometers over technical roads at close to 60 kph sustained. But the guys he's beating consistently can also put out power under the same circumstances. Cavendish wins not because of superior power, but because of superior speed, and except under the most exceptional circumstances most power goes into wind resistance.

Look at a Tour finish and the final 200 meters aren't enormously faster than the 200 meters preceding. Cavendish, for example, has Mark Renshaw, a man who's won Tour sprints himself, leading him out with his own maximal effort. No -- the sprint of a Tour stage, in addition to critical factor of position, is a time trial, and time trials are won by power balanced against aerodynamics. Cavendish is so unprecedentedly successful because he has one of the all-time great sprinting positions in professional cycling history... to beat him you've not only match his power but substantially exceed it.

The aerodynamic frame is icing. But the primary factor in aerodynamics is body position. 100% of great time trialists have great body position, going back as far as photographic history records. And Cavendish looks like a time trialist when he sprints. That he's able to hold that poise in the midst of so much chaos is remarkable.

2 comments:

GM said...

Hello (sorry for my english, I'm french...),

interesting analysis (as always)... with more and more aero bikes on the market we have more and more figures about the gain they provide. Typically the best TT bikes seems to provide, very approximately, a gain of around 40W at 40 mph. The new Cervélo S5 is supposed to provide a gain of 20 to 30W at the same speed.
I don't have figures to compare the aerodynamic drag between different positions, typically "normal", agressive, very agressive...
I wonder how much I would gain by switching from my rather agressive position to a more agressive, TT like (without the TT bar). I can't bent more because my knees touch my torso when I'm in the drops, so I have to move my saddle forward and upward, and my handle bar forward and downward

best regards

John E. Dunn said...

Cavendish isn't about power, he's about technique, timing and acceleration. A great example was stage 5 of this year's Tour.

Stripped of his lead-out on an uphill finish he improvised on pure instinct, first 'hiding' back in the bunch to give him the element of surprise.

Approaching the line he jumped on to the wheel of Geraint Thomas, a rival leadout, trailing him to the leaders, remaining out of view.

Finally, at precisely the right split second, he jumped out wide right and tore past Hushovd and Gilbert, both of who later said "where in the hell did he come from"?

Power, yes, but perfectly used to waste no energy and to ambush his rivals. Watch it on ITV4's replay site - it was the moment I decided that Cavendish is in fact a genius-level cyclist.