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TRAINING NEWS

Pedaling Technique and Efficiency



By Chris Carmichael

Using a powermeter we can determine the wattage George Hincapie produces over any portion of a race or training ride. What is more interesting to see is how his power delivery fluctuates. Some would say 500 watts is 500 watts, no matter how you get it, but I think there's an important element they are not considering.

If you take a look at graphs of power delivery through a pedal stroke, like those developed by Jeff Broker, Ph.D., at the US Olympic Training Center in the early 1990s, you see that the vast majority of a cyclist's power is produced in the downstroke portion of a pedal stroke. Power production falls drastically as the pedals approach and pass through the top and bottom of the stroke. The power of the downstroke is so great that it negates the opposite leg's capacity to produce any power during the upstroke. The best a cyclist can do is unweight the upstroke leg, or try to get it out of the way of the pedal coming up at it. In some senses, the upstroke leg can be seen as working against the rider. A portion of the force being applied in the downstroke is going to lift the opposing leg instead of propelling the bicycle forward.

Biomechanical efficiency is the element people miss when they say a watt is a watt, no matter how it is produced. In George's earlier years, when he was less biomechanically efficient, he had to produce 550 watts over the same ten-minute section of pave in order to stay with the leaders. This was because he was fighting his own forward progress from within his pedal stroke. In the final 50km, he did not have the energy to stay with the leaders, whose superior efficiency allowed them to go the same speed with a lower sustained power output. Through training, his mechanical efficiency improved to the point where he can afford the energy cost of being one of the race leaders, and even attack and sprint in the final 10km. The Classics are nearly 300 km and 7 hours of riding a bicycle over terrain American suburbanites wouldn't drive their SUVs over. To be one of the "hard men" who can win such an event, you have to be extremely efficient with your power delivery.

The way to improve mechanical efficiency is to learn to apply force through as much of the pedal stroke as possible, especially through the top and bottom. Overgeared, high-power, low-cadence workouts are essential. Climbing hills, seated, in a big gear forces George to keep force flowing to the pedals over the top and through the bottom of the stroke. It is the only way he can maintain enough momentum to keep the bike moving forward. Later on we add sprints up steep hills, again in a big gear and with slow, rolling starts. During these workouts, George has to accelerate through increasing resistance. In races like the Tour of Flanders, with 16 steep slippery cobblestone climbs, poor pedaling economy results in a spinning rear wheel, followed immediately by a dismount and a run in equally slippery cycling shoes.

One interesting note: Mountain bike racers were the most biomechanically efficient pedalers in the tests from the US Olympic Training Center. Their efficiency comes from having to apply high force in a 360-degree manner so the rear wheel won't break loose in steep, loose terrain.

 




 

 

 

 



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