Originally Posted by elcruxio

You probably shouldn't post if you take disagreements personally.

I just had to verify the math on that 109% figure. Using my own measurements I got 32 degrees knee flexion if my foot was pointing 45 degrees heel up. With a more reasonable 25 degrees heel up I couldn't reach the pedal. With 30 degrees heel up I got a crisp 10 degrees knee flexion. I once tried 15 degrees and boy that wasn't fun.

perhaps that 109% figure works with the cleat all the way forward on the shoe right under the toes with the rider ankling down like crazy, but I wouldn't call that comfortable, efficient or stable. Personally I prefer far less heel rise and cleats placed aft. That's more stable and more energy efficient as there's far less calf usage.

High saddle also isn't very aerodynamic so there's incentive to try to go lower.

using the same numbers with the 103% I got 35 degrees knee flexion with an even more reasonable 20 degrees heel up. Effectively that gives me space to drop my heel pretty far down on climbs or when grinding is otherwise necessary.

Oh btw, my knee issues disappeared after I stopped using formulae and just dropped my saddle where it's comfortable. And I can now ride centuries which is a nice bonus.