Tuesday, December 08, 2009

Force Reps

I was just looking at data from a force reps session (each interval is 18-20 pedal strokes at max pedal force in the 53-12). My wattage is typically a consistent 600 watts for the efforts. But the thing that caught my attention was the torque.

WKO+ tells me that my peak crank torque (actually it's virtual crank torque, which is calculated from PT rear hub wattage and cadence) at the max efforts is about 1160 lb-inches. If you divide that by the length of my cranks, 172.5 mm (6.89 inches), you get 168 pounds (1160 lb-in divided by 6.89 inches).

My max squat is just a little more than that. I don't really know my max squat weight, because I never do (and don't plan to ever do) 1-rep max squats. But based on the rep chart in "The Cyclist's Training Bible" I think it's about 190 lbs, which would be about 1.3 time my body weight, which is fairly typical.

The thing that has me a bit confused is that I'd assume most of the pedal force is coming from the down-stroke. If that's the case, I'd only be able to put out a little more than half of my max squat force when pedaling (if you assume the upstroke has maybe 20% of the max downstroke force, it'd be 70% max squat force, or 0.7 x 190 = 133 lbs right?).

I need to think on this one for a while. Feel free to enlighten me in the comments section if I've missed something or messed up the calculations. Am I putting out more force than I think with my upstroke? Am I putting out more than I think with my downstroke due to momentum and body weight factors?


Anonymous said...

One thing to think about is that your force reps on the bike are more of a full body thing than doing your squats. You pull with your arms and stabilize with your core. Additionally, if you do the force rep while standing, I think you're doing more than just driving down with the force of your single leg but leveraging the weight of your body as well.

The Professor

Robert Jordan said...

I do the force reps seated. I guess there are substantial forces coming from upper body and core muscles that contribute to the pedal force that don't come into play when I do squats. Those non-leg forces combined with the upward force of my off-side leg must combine to equal my two-legged squat force.

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