Cadence Drift at a Steady Power


Today I threw over to do some supplemental endurance work and loaded up Taku. Taku is a 30 minute workout categorized as an endurance workout (if you are not familiar with it). I only shifted the gears once and that was going from the first interval to the second, I resolved to do the workout single speed style.

In the third interval I noticed my cadence slowly but surely dropping while my power stayed steady (or so every slightly crept up). See the below Golden Cheetah trace with the upper trace being cadence and the lower trace being gear ratio. The power is more or less steady.

I have a conjecture as to what is going on. I believe my pedaling is becoming more efficient or perhaps more steady around the full pedal stroke. That is the application of force around the full pedal stroke is becoming more smooth as I focus on that. Is that a reasonable belief? Do you observe the same in your training and riding?

So, does that what was once a light spin eventually becomes mashing and using fast twitch muscle? It can be frustrating as sometime it might take me a while to find cozy gearing and then a few minutes later I look to see I’m “mashing”.

What trainer ae you using, and what power source? I’ve seen this happen with some smart trainers, because the power calibration drifts over time as the brake heats up. That could be what’s going on here - the trainer thinks it’s holding at constant power but the power is actually steadily increasing, which you see as a drop in cadence.

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I have a Cycleops “dumb” trainer and the power source is my Stages left side crankarm power meter.

how does it feel when your cadence is higher? Do you feel like that’s a comfortable cadence? It could be you are gradually regressing to the cadence you are currently most comfortable with.

I also train with a ‘dumb’ trainer, using single-sided power with Favero Assioma pedals. I get cadence drift in the opposite direction, i.e. as an interval/session wears on, I might see an increase in cadence for the same power output.

In my case, I thought it might have been the trainer tyre warming up over the course of an effort. I reckon there definitely is a bit of this going on at the beginning of every interval, e.g. 88rpm would yield about 240W, but this will quickly creep up to 92rpm within 30 sec. But this only explains the cadence increase for the first 30 sec - 2 min.

For longer efforts, an observed cadence increase (that actually often comes with a HR increase) is probably due to my left leg (where the power meter is situated) fatiguing and not being able to put out as much force in the pedal stroke, so an increase in cadence compensates for this and gets me to the power target.

Maybe for you with the cadence drift downwards, your right leg is fatiguing and the left leg is picking up the workload. Since you’re keeping an eye on the power, the cadence will drop as the left leg does more work per pedal stroke.

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Interesting. It still seems to me like something is drifting, be it the resistance in your trainer increasing over time or uneven fatigue in your legs skewing your l/r balance. It doesn’t look huge to me, nor does it sound like it presents a huge issue. But probably still a good thing to be aware of, even if you just have that filed away in the back of your head during a workout.


Yes, my average cadence for 2020-2021 training (starting in Sept with traditional base mid-volume and now on sweet spot base low volume one week 3) is 86 rpm and I’ve maxed out at 160 on some of the form sprinting drills. The average cadence in the lap I highlight is 83 rpm.

You’re probably just settling into your natural cadence.

What’s your average cadence on an outdoor ride? Mine’s consistently around 82, MTB or road.

I couldn’t hold 90-95 rpm on a Z2 indoor ride. Not only would it take more mental effort on a ride where I expect to just zone out, but higher RPM also increases sit bone pressure.

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Looking back to 2019 I see my summer monthly averages ranging between 80 and 85 rpm. So there might be something to the notion I am reverting to a more natural cadence. Yeah, if I were outdoors on a ride for ice cream I would probably be tootaling along at a lower cadence even at the same power.