Login required to started new threads
Login required to post replies
I have a pair of SIDI's and a pair of Carnac's. The distance from the pedal spindle to the floor of the shoe is a good bit further in the Carnac...maybe 3/8 of an inch? It's enough that I have to move the seat height to get the same knee bend at the bottom of the pedal stroke.
This got me to thinking about what difference it makes in the pedal stroke to have your foot/spindle distance changed...isn't it more of a difference than just changing your seat height, (not just because seat height changes your effective top tube length, etc.) does it change the pattern your foot actually traces in one complete revolution as viewed from the side?
It seems like the greater the distance above the spindle, the easier it would be to create changes in the pedal stroke by adjusting your foot angle during the stroke...changes which could be good or bad, depending upon what these changes were.
Quid quid latine dictum sit altum videtur
(That which is said in Latin sounds profound)
This is an excellent and insightful question. I used to work for Time Sport USA as one of their National Tech Reps. Basically, we went to bike shops to educate them on the features and benefits of Time pedals. One of the features and benefits we used to sell Time pedals with was closer proximity of the metatarsil joint (sp? ball of foot)to pedal axle. In those days, when people used Time brand pedals AND Time brand shoes, they had about the clost axle to foot interval you could get. Anyway: Time spoke about the benefits of "lower rocking torque". I picture "rocking torque" as the effect wood pedal blocks have on your first tricycle- when you try to push down hard on the pedals they want to twist around and fly out from under your foot. The closer your foot is to the pedal axle the more direct angular application of forces to the drivetrain. That is my admittedly rudimentary understanding of the concept. Since then other pedal companies have developed pedals that are closer. Using a Sidi T-1 and Speedplay Zeros seems to be about as close as you can get that I am aware of, short of a custom shoe. I hope that helps. I am looking forward to other information, potentially from engineers who have a more formal understanding (and explanation) of these issues.
Tom Demerly
The Tri Shop.com
"I picture "rocking torque" as the effect wood pedal blocks have on your first tricycle- when you try to push down hard on the pedals they want to twist around and fly out from under your foot."
Yeah! That's what I'm talking about! Whataboutit engineers?
Quid quid latine dictum sit altum videtur
(That which is said in Latin sounds profound)
The engineer: "The tangenital application of drive forces, combined with the length of the lever arm, expressed as "Y" (foot-pounds of torque over watts squared exponential) using the universal equivalent is roughly equivalent to the blah, blah, blah....
Simply stated: Closer to the pedal axle makes good things more and bad things less. My .02.
Tom Demerly
The Tri Shop.com
We talked about the foot higher from the pedal spindle, what would having a pedal that actually allowed the foot to go further out from the bottom bracket (either pivoting, like a stirrup; or a depressed platform) ...even PAST the spindle, give any advantage?
I don't think so, because the lever would be only as long as the BB to pedal spindle at 3:00, but would be LONGER at noon and 6:00. It "seems" to me that you would get better power if you could reverse those lever positions; i.e., longer lever at 3:00, and shorter at noon and 6:00.
Methinks I thinks too much...
Quid quid latine dictum sit altum videtur
(That which is said in Latin sounds profound)