It's getting warmer. Got to me a bit on my last ride. So I started thinking about it. The issue is about dissipating heat. What heat? Heat energy wasted when turning sugar and fat into pedal strokes... ie inefficiency. A little searching about efficiency doesn't turn up much you can do, at best "maybe be more fit or skinnier helps? .. shrug?". But one thing does seem to correlate very strongly: cadence.

There are a couple of studies and plots but they all show very significant differences even between a cadence of 90 and 80, 80 being more efficient. There are strong arguments raised for riding above optimal efficiency, one being higher cadence provides more power. That seems to imply cyclists are limited in the force department, interesting topic in its own. And some suspicions exist aparently that this is all the more true if you're on EPO.

Anyway, maybe the optimization changes in the heat? If you're power limited, maybe high cadence is better. If you're heat limited, maybe the tradeoff shifts down? It's not a tiny effect actually. Depending what assumptions and curve you look at this might be a 10 or 20% effect. That could raise your power headroom a bunch, no?

Here's an example:

Spinning vs Mashing... is it really true?

The right plot to look at is probably GE, which seems to precisely be about heat vs mechanical output.

Thoughts?

Actually I suspect this comes a little intuitively? But so many people pedal by the numbers that intuition may not always apply.

My interpretation is that one should consider pedal force rather than cadence.

One's body is optimized to lift one's own weight with either one or two legs, although not necessarily repeatedly from full flexion.

Anyway, once one hits 100% of one's weight, then more downward force picks oneself off of the saddle, with two options, pulling up to increase force, or increasing cadence. Pulling up is limited in power, and perhaps good for short bursts of energy but not necessarily long endurance pedalling.

Thus... more power ==> higher cadence

But, if one isn't racing, then there is no reason to be running at 100+ RPM.

What is the optimum cadence? It may well vary from person to person, as well as varying with training.

I ride at my "naturally selected cadence," and it is not a number. It is determined by a variety of factors that change by day: energy level, average grade on the route, what heart rate zone I'm shooting for, etc, etc. So some days it's 75, some days it's 85. Every once in a rare while, it will be near 90. It's not something I pay attention to while riding, it's just a metric I track when looking at rides overall.

I personally have not noticed a difference in heat output at lower vs. higher cadences when climbing grades, unless we're talking about much lower. My standing cadence while climbing tends to hover around 60rpm, and I often use periods of standing to cool down, as high rpm on steep grades is making more watts, and more power to the pedals means more heat... so I can definitely see something to it.

...but I tend to use "soft pedaling" to combat overheating. Easy, even cadence (very light pressure on pedals) try to maintain an even speed at or above 15mph and let evaporative cooling do it's thing. I have absolutely noticed that dropping below 11mph, it gets real hot, real fast. So for some hills, a squirt of water from the bottle, directly into the helmet vents, seems to do the trick.

It is true that the self-selected (and lower) cadences have been shown to be more efficient, meaning that more of the body's total work is used to make the pedals go. And also, more of the leg work spins the crank (FE, force effectiveness).

Yet there is one thing that always concerns me about it, and I googled up the paper being discussed (The relationship between cadence, pedalling technique and gross efficiency in cycling) to check. It is that trained cyclists are likely to train most at those self-selected cadences, and as a result of that training one would expect them to have a better pedal stroke (FE) and have conditioned themselves to be more efficient (GE) at the trained cadence. That would also be consistent with elite riders, who train generally at higher cadences, being more efficient at those cadences.

So if my concern has merit, these differences in efficiency might be due in part or in full to training and are not a consistently applicable physiological fact.

I thought the paper (or maybe a different one) specificially compared efficiency of riders at their self selected cadence only, plotting the trend based on people using different selected cadences. I'm not certain though. I'll have to look again. I also don't pay any attention to cadence actually other than what feels right or with a little push up or down for some training or situational reason. I'm pretty sure if heat puts pressure on the situation that the "feels right" approach will react well to that, but I never took notice.

First of all, everybody is different. Also, as pointed out above, the data mighr simply be confirming a trained condition.

But it's easy enough to apply the theory and see how it turns out for you. On any stretch long enough, try maintaining the same speed using either of two adjacent gears, ie one feeling a bit low, and one a bit high and see how you feel. If you have a heart monitor, see which allows you to maintain that speed with a lower heart rate.

For my part, I let my legs tell me and ride my natural cadence, which has increased over the years, but is still at the lower end of the range people talk about. Also, possibly because I didn't have them available when I was younger, I still can't spin up long climbs in a super low gear, and prefer pushing a higher gear using strength vs. speed.

IMO - unless you're training for competition, or have another training goal, ie. improving climbing ability, listen to your legs and ride however feels best, regardless of anything you read or hear.

FWIW - I used to ride with someone with breathing issues because of which he couldn't spin low gears. He set his bike up with monster high gearing, and could produce and sustain serious power mashing big gears. In his case, it was very clear that he could get more work on less air at lower cadence.

When discussing efficiency we are comparing performance between two or more alternatives. I would think that such a comparison would require variation for each person and type of effort. There would be a considerable difference between sprinting and climbing requiring much different type of pedaling. As an asthmatic, optimum for myself is that combination of cadence and power output that permits turning the pedals on my long rides, say 50 to 60 miles. Another way of saying this is if racing up the Empire State Building by the stairs, almost all of us would be better off taking the steps one at a time rather than two at a time.

Riding fast creates a wind and cools you down. As soon as you stop, you'll get warm again. Therefor: avoid disc brakes in the summer.

Or any other brakes capable of applying about 0.5 to 0.6 mg of stopping force (about the endo limit, for a road bike) to the front wheel... yeah, so any half decent ones unless your m is maybe particularly high.