Old 03-03-19, 12:17 AM
Super D
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Bikes: C'dale Road, Giant TT, Felt Track, DB MTB

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Originally Posted by carleton View Post
First, it matters how much torque you produce.

Letís say the 90ís are stiffer than the 70ís, if you arenít strong enough to flex the 70ís, then having a stiffer sole wonít matter.

Also, the difference could be in weight savings, not stiffness. And the 90ís being so light that they are less stiff. Like the difference between cromoly and carbon saddle rails or handle bars.
I hear you, and there are other factors to consider as well, such length of the levers (feet/shoes/soles), angle of the levers under peak torque and where peak torque is applied in the pedal stroke, etc. However, as long as enough torque is applied to induce flex into the less rigid of the two soles (EC70 theoretically), then the EC90 would be advisable to maximize energy transfer (I believe). My question really then comes down to, how much torque is required to flex the EC70, right? It's too bad there isn't a sole stiffness guide, just as there is a sizing guide for shoes. But then we'd need to have some sort of torque measurement per individual, in order to find our place within the guide.

I can generate healthy watts, but if I'm efficient in power application through the pedal stroke, then I'm applying lower torque during each stroke than someone who is less efficient with their pedal stroke, and a stiffer sole may not be needed. In reality, I don't know how much torque I generate and how to match that to a shoe sole. What I do know is, when I swapped to stiffer drop bars and stem on my road bike, the change was substantial. Less flex converted to better energy transfer when sprinting. I think a stiff sole would benefit me similarly in a cycling shoe for track and road racing.

Interesting point you brought up with regard to weight. I'm curious about the real differences between these two soles.
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