There’s a sequence in the great La Course en Tete, the documentary on Eddy Merckx, in which the filmmakers show a sprint unfold in a head-on view as the riders barrel toward the finish line. To a rider, their cadences are north of 120 rpm and they rock their bikes side-to-side hardly at all. In fact, each and every sprint in the film or any film of the era have something in common. The bunch sprints of the day are displays of redline agility, typified by furious pedaling in wound-out gears.
In another segment in the film the Cannibal climbs on a set of rollers in his garage. They consist of large drums, at least 15cm in diameter, and Merckx rolls them up to centrifuge speeds until his bike is bouncing on those drums. For those who watch carefully, Merckx’ frame flexes under his effort and his bottom bracket sways as if there was a wind stiff enough to torque the frame.
To my eye, these efforts feature two limiters: agility and frame stiffness. Cultivating the agility necessary to pedal 150 rpm is an incredible challenge for many riders. To hold that kind of cadence for more than a second or two is superhuman. It’s fair to ask why riders needed to pedal that fast. The fact is simple: the only way for a rider to generate his full wattage was to do so by pedaling a relatively small gear at gyroscopic speeds. Big gears caused riders to flex the frame too much, making the bike harder to handle. Rocking the bike exacerbated the flex issue.
So what has changed in 25 years? Quite a lot, when you add it all up.
First is the frame and fork. The difference between a 28.6mm-wide down tube and a down tube measuring more than 60mm in diameter is enormous, but that change didn’t happen overnight. Increases in stiffness occurred gradually and an increase in stiffness in one part of a bike showed a weakness elsewhere in the bike. It was only after frames became stiff enough that you couldn’t make the chain rub the front derailleur when in the big ring that frame twist became an issue.
But of course, the frame and fork were only the starting point. Rims were beefed up, and spoke tensions rose, decreasing the need to tie and solder them at crossings. Bars and stems got a dose of stiffening as did crank arms. And let’s not forget the changes to both pedals and shoes that increased a rider’s ability to deliver power to the bike.
All these changes can be summed up in a single part: The 11-tooth cog. Greater stiffness meant that bigger gears could be used, and while for the most part sprint speeds did inevitably rise, the bigger change was that more meat in the drivetrain brought cadences down.
It’s inaccurate to say that the riders are more agile now, but the drop in cadence has given riders a greater degree of control. While I haven’t conducted a survey of sprint finishes over the last 40 years, I wouldn’t be surprised if you found that crashes in final sprints had actually gone down.
More than anything, what changes in bicycle technology has given us is the ability for an athlete to show his full potential in the final 200 meters of a race. A sprint, after all, should not be defined by a rider’s ability to refine movement and flex the bike no more than can be controlled, rather, it should be a measure of his full power.
Cavendish Image: John Pierce, Photosport International