Noisy Cadence


I have a Kickr Bike and also a Wahoo shoe-mounted cadence sensor that I use when outside, but also use inside since it’s on my shoe.

My problem is that the cadence data is very noisy:

The Kickr Bike is mains-powered and I have a fresh battery in the shoe-mounted sensor. Does anyone have any idea why the cadence data is so noisy? I did the GCN Endurance workout today that takes your cadence down to 60 and it was impossible to use the cadence reported in the app: I had to sync myself to the cyclists in the video.

There’s no way my actual cadence is fluctuating like that. Any ideas?

  • Mark

How is it paired, via ant or Bluetooth?

Bluetooth. I have SYSTM running on an iPad

Odd that it’s the only one sensor which isn’t smooth. I’d expect them all to have issues. But I thought the KB has a built in cadence sensor?

Which source did you have selected for cadence, the Kickr Bike or the shoe pods? Try selecting the KICKR Bike and see if you have the dropouts. That will narrow down the source of the error.

FWIW, I always get way better cadence data from an actual cadence sensor on the bike than using a trainer. The trainer can only estimate cadence from the pedaling torque pulses it feels. This can work OK at higher power levels at more typical riding cadences where you generate regular power pulses while pedaling, but it often doesn’t at lower power high cadence intervals, especially if you’re spinning rather than mashing. I use various cadence sensors on different bikes, a magnet sensor type on the left chainstay, or a sensor that straps on a crank arm, or the cadence output from crank or pedal power meters.

I agree about the limitations of power-meter-based cadence based on pulsing, but many cycle computers force you to use it if you are using a power meter which relies on torque and rotational speed, which actually makes a lot of sense for consistency’s sake. I haven’t tried it, but it looks like SYSTM will let you pick a separate cadence source than the power sensor.

The crank-arm magnetless sensors are slow to respond when you start rolling, based on my examination of the data in my outdoor ride fit files, and I personally always manage to dislodge the chainstay sensors with my foot at the worst times. No perfect solutions.

Power meters on the crank, whether spindle, crank arm, spider or pedals, must measure actual crank rotation to determine power. The crank power meters I’ve used all send separate accurate cadence data as well as power, and in some cases, other pedaling metrics. For example, I can use my trainer for power and my pedal PM as the source for cadence.

Thanks for the suggestions. I’ll try removing the shoe sensor so that it only sees the Kickr bike itself.

It was my understanding that the Kickr Bike (not a Kickr trainer) has a discrete cadence sensor built in.

Yes, that’s correct. I also have one on my shoe for outdoor purposes, and both are linking to SYSTM. I’ll disconnect the shoe one

The shoe-mounted cadence sensors, in my experience, are garbage. Fine for running, but somehow unreliable in all my rides.

Power meter-based cadence sensors only work when you apply power. Quarq ones are amazing, as whenever you pedal, there’s always a little force. KICKR ones are fine for the trainer. Sure, there will usually be a dropoff after a big sprint interval, but whatever, good enough.

If you’re really concerned, go with a magnetic sensor like the Wahoo Blue SC. Extremely accurate and reliable.

Also, clean your space of interference. Don’t track cadence or power from both your computer and head unit. That can cause drops as the sensor switches back and forth for reporting. Also, split the control and reporting between Bluetooth and ANT+. I’ve found the power meter is more accurate and trainer control is faster in BTLE, but all other sensors are more reliable in ANT+.

If the KICKR Bike has a discrete cadence sensor built in, it’s not particularly accurate when you aren’t applying power. Unfortunately, there isn’t enough clearance for me to mount a crank-arm sensor, nor will a magnetic speed/cadence sensor work. I have thought about putting my Assioma power-meter pedals on my KICKR Bike for the winter, but those cleats aren’t great for indoors.

Hey guys,

I discarded the shoe sensor and the data is much better now:

I can actually see my cadence now :grinning: Thanks for the help,

  • Mark