For those of you who know me, I have a foot in both camps - literally! I have clipless on the right pedal and a toe strap on the left! Good to know that energy expenditure to mechanical power transfer is equivalent for normal cycling and that use of flat pedals/toe straps is not a barrier to riding well nor progressing within the SBC groups.
This is one way of measuring cycling efficency. What I'd be interested in seeing is if there is any difference in deployment of leg muscle groups to deliver the same power output for each type of pedal. Use of Electromyograms (EMG) and a WattBike could discover these differences.
Why would this matter? If the majority of power delivery over each revolution is provided purely by the quadricep muscles, this cyclist may fatigue earlier than a cyclist whose equivalent power delivery is spread between the other leg muscle groups (hamstring, etc) over each revolution. The latter cyclist has more reserve capacity to sustain the workload and develop/sustain higher power outputs over a longer period of time.
Some day, I'll book a WattBike session to see what my left and right leg power peanut curve looks like but anecdotally I certainly don't feel any difference in how my left/right leg operate on each pedal stroke and I don't walk in circles due to any asymmetrical leg muscle imbalance!
I've always been surprised and amused by the reaction of road cyclists when they see my footwear and pedals (sports shoes with flat pedals and Power Grips straps), since I've always been confident that I'm at no significant disadvantage. My shoes were commented on at many of the feed stops on the Ride Across Britain, usually along the lines of "I take it your not cycling in those shoes?". People seem to be genuinely concerned that I'm suffering significant power loss, and I appreciate that concern, even if I think it's entirely misplaced. As you can imagine I was therefore very interested to read the following.
"Cyclists, coaches, and equipment manufacturers claim that cycling-specific shoes coupled with clipless pedals are ‘more efficient’. However, scientific evidence supporting or refuting these claims is lacking."
Well not any more - it's now scientifically proven that unless you're flat-out sprinting, running shoes and flat pedals are just as efficient as cycling shoes and cleats (since 2015 in fact).
Since I don't do sprints, I'll just stick to my current set up, happy in the knowledge that I'm not losing out to anyone else with their fancy footwear. In addition, in my relatively short cycling career, I've personally witnessed 4 accidents to very experienced riders due to not getting un-clipped in time, one of which involved damage to the bike and one in damage to the rider. On the other hand I entirely accept that if you like being clipped in then there's absolutely nothing wrong with that either. And when you beat me in a sprint I've got an excuse!
The results of the separate sprint study are here: