Kickr Cadence Spike - 120rpm

I have a kickr’21 and there are always cadence spikes in every ride on Zwift where it would randomly jump to 121ish RPM. It sometimes happens when I’m climbing and I crest the hill and stop pedaling on the way down. It’ll go from 80rpm to 120rpm and then back to 80 rpm…

I had the Kickr Core and never had issues.

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IDK about your specific situation, but trainers estimate cadence by counting torque pulses assuming that there are two distinctly detectable torque pulses per crank rev. That works in many situations but there are some where it gets tripped up due to how an individual might be pedaling. Often, spinning at low power and/or high cadence doesn’t produce consistent torque pulses. Also problematic is situations where you need to make a distinct decrease in cadence. IMO, it’s much better to use a separate cadence sensor which will produce consistent and reliable cadence info. Considering all you might have invested in your training setup, it’s a very small additional expense. You can find cadence sensors on line for under $20.

How do you attach it to the fly wheel? Weird I have the core for a couple years and on my wife’s bike and I have no issue. Move up to the more expensive version and it has been troublesome.

just had an aha moment and remember the cadence sensor attaches to the crankarm.


Right. That’s the thing. The trainer can only infer what the crank is doing whereas a cadence sensor directly measures it. As far as the Core vs the Kickr, IDK.

I don’t use a Wahoo KICKR, but on the trainer I do use had the same issue. I switched to using a separate cadence sensor and all was well afterwards.

It doesn’t even have to go on the crank arm, the Wahoo cadence sensor comes with a mount you can use to attach it to shoe straps. This way I can use 1 sensor on all my bikes.

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I wear different shoes on different bikes (trainer, road, gravel, mtb) so I’d either be swapping the sensor between bikes or between shoes. Maybe you can strap it to an ankle, like a house arrest ankle bracelet.

I’ve had success just tucking it in the cuff of my socks, when swapping it over when I wanted cadence feedback on single leg drills.

I’d make sure your KICKR has the latest firmware. Wahoo often fixes issues like this with firmware updates.

You update firmware using gifs Wahoo Fitness app. It’s fairly straightforward. Ask if you have questions.