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Power transfer through different pedal models / systems

by PWald
Tue, Jun 16, 2020 22:30
3

Evening all,

I've been riding all my bikes, including my road bike with SPD forever, but am musing a swap to another system (for comfort reasons). This more of a curiosity but when reading around SPD-SL / speedplay etc, I often read claims about "better" power transfer, or "more power". Admittedly it's been years since I scraped my A-level physics but my memory of vectors, forces, moments etc is good enough to think I can call bullshit on these claims, or at least the way they are worded. I get it that an increased contact area will improve comfort, but how can people claim one pedal system claim to increase power (transfer) compared to another? Assuming the sole of the shoe is stiff enough, the power generated by the rider is going to pass into the pedal in equal amounts regardless* (OK, there might be an absolutely minuscule difference for some reason or another, but surely not enough to bother even Incremental Dave B). Or am I missing something and this is just marketing twaddle, and they should stick to the comfort claims?

TIA

PW

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3 comments

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Judge dreadful | 4 years ago
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It's fairly simple. In order to make more power, you have to be pressing with more force, and / or rotating the cranks at a higher rpm / both. Any pedal system that allows you to press harder, spin the cranks at higher rpm / mixture of both, will lead to an increase your power, relative to a less secure / stable / comfy binding. Whether that's because the platform is more comfortable,  the binding is more stable, the system is lighter, all these things count. You'd need to see power graphs and pedal dynamics / pedal effect graphs to see the numbers, but most people find that the more stable bindings afforded by SPD-SL / speed play etc, compared to SPD, give much smoother graphs, and better effect balance, and that's where the extra power is coming from.

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PWald replied to Judge dreadful | 4 years ago
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Indeed, to both replies...  I guess that's what I'm getting at in that it seems to be down to a comfort thing so much more than anything else, so to suggest in any marketing material (through the use of suggestive language) that a pedal system mythically increases power transfer (and in doing so somehow breaks the laws of thermodynamics) is disingenuous.  But I'm not a complete muppet so accept that is what marketing is all about.. 3

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Joe Totale | 4 years ago
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You're right when it comes to the power transfer.

However, I definitely find road pedals more comfortable to ride in, especially on long distances due to the larger cleat. I'm happy to use a less practical system than MTB pedals for this extra comfort.

I suppose as well that a more comfortable foot can also be a more powerful one!

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