Monday, May 31, 2010

Did Cancellara Use Illegal Motor Power At The Classics?

When I first read the story this morning via a Twitter shrapnel, I dismissed it as an unimpressive attempt at comedy. The story was titled "Former Pro Says 'Mechanized Doping' Is Real."

4 hours later, people were crying "mechanized doping, mechanized doping!" and sharing another story from Belgian source Sporza.

In it, Davide Cassani, an Italian commentator for RAI, implies that pros (like Cancellara) maybe using at races a bike retrofitted with a certain kind of motor. From first impressions, it looks very much like a modified Gruber Assist.

Cassani remarked that if he were given a bike like that at his age of 50, he'd probably win a stage at the Giro d'Italia himself! Among his other claims were that the mechanism has been in existence since 2004 and pros have even used it in the past.

A shady video (below) was then made by "CyclingmanagerItalia", whose real name is Michele Bufalino, showing how Cancellara may have used this device during Paris Roubaix and the Tour of Flanders. Question remains : Who started the rumor about Cancellara using a motor?

The Gruber Assist, the interesting mechanism that maybe at the center of these rumors, happens to be a 900 gram (1.98 lbs) motor-control unit powered by a 1000 gram Li-Mn battery that is placed in a saddle bag from where cables and electronics run. The motor is switched on and off or placed into pedaling frequency recording mode by a button on the handlebar end.

The motor itself is designed to fit inside a 31.8 mm diameter seat tube, thus hidden from view. The drive mechanism appears to be a 90 degree bevel gear arrangement as shown in the pic below. The manufacturer claims that upto 200W of extra propelling power is delivered to the rear wheel at a rated cadence of 60 RPM, with a running time range of 45min-1.5 hours.

A peek at their website yields some specs for the battery. If human pedaling contribution was ignored, the battery has 4.5 A-hours of capacity at 6 A current and 30V rating. What that probably means is that a 6A current will discharge the 4.5 Ah capacity battery in 45 minutes. If the manufacturer's claims are true, the exaggerated 200 Watts could be from :

30V x 4.5 A-hours = 135 Watt-hours or 135 watts for an hour.

Of course, batteries work like human power. The faster you discharge energy from the battery, the less it can totally supply. This is called Puekert's effect. So the numbers above can drastically change with higher energy demands.

So suppose these video allegations from Cassani are indeed true, and suppose the motor was indeed suitable for the famed cobbles of Roubaix and the Kepelmuur (9.3% average, 19% max). What then?

On the hill section where Cancellara attacked dominantly, the motor must have been expected to supply an extra 200+ watts of power for him to power away from Boonen. On the cobbled sections to Roubaix, it must have been expected to provide upto 250 Watts of extra power to counteract wind resistance while accelerating away from the bunch. I'm not sure of the wind conditions, but with headwinds, add another 200 Watts give or take to that figure, for every 5 mph increase in wind speed.

All in all, with the weight requirements that pro cycling demands, the energy demands imposed on the battery are substantial. Not only is the discharge rate very high, such as that asked for in an attack during the race, but the gravimetric energy density (Wh/kg) of the battery must also be high. If the battery weighs 1 kg as claimed, you're looking at a desired supply of upto 200 Wh/kg and over. My first guess tells me that a Li-Mn battery could not meet these racing specific demands. But I maybe wrong given the rate at which battery technology is getting better. See the graph below :

To the lame man, more important questions, however, are the following :

1) How was Cancellara was able to get away from not being noticed in spite of sound from the motor? Observe in the video below the amount of noise this thing makes :

2) Where did he place the 1 kg battery, if he didn't have a saddle bag?
3) The seat tube must be internally drilled out with a reamer for the drive unit to be correctly placed. The drive unit would have to be made to work with the SRAM bottom bracket, as the off the shelf unit only works with Shimano Hollowtech II. After that, all parts would then have to be hidden from view, given the number of components in the assembly as shown.

Surely, if this event took place, someone knowledgeable in how to do all this would have assisted at the Saxo Bank camp.

This may either be a good one for the spoof books, or something just so good that it doesn't appear true.

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