I’m curious if anyone else is experiencing this phenomenon with their Kickr. When I train on the front large chainring, the cadence is displayed pretty much 30 steps too high. So when I’m supposed to pedal at a cadence of 80 and I feel like I’m hitting it, the cadence displayed is mostly 110, which sometimes changes to the exact cadence of about 80 for a few seconds. If I train on the small chainring, the frequency is displayed correctly. This is not a disadvantage when I train in ERG mode, as the resistance is set correctly by the Kickr and I don’t have to shift gears anyway. This is not critical in level mode either, because I set the level in full frontal mode, for example, so that I hit my resistance and the optimum frequency in the best possible way without having to shift gears.
I also have the impression that the average wattage values displayed during training are consistently much lower than those measured on my outdoor rides with the Garmin Rally RS200 wattmeter, for example. I have much higher average wattages with the Garmin when I feel less effort.
I have found cadence reported by trainers to be somewhat unreliable. They can’t measure cadence directly but instead infer it from power pulses, 2 per revolution, from your pedaling. This can work well when pedaling steadily with at moderate to high power, but in other situation where your pedal stroke might vary, it doesn’t work well. Best is to get cadence measured directly, either from a cadence sensor, a crank based power meter, or pedal power meters. Cadence sensors can be had for ~$15 US on Amazon.
I’m not sure what version of Kickr you’ve got, or what app(s) you are using where your cadence is off (or your power doesn’t quite feel right either).
I’ve got a Kickr '18 (version 4 I think they call it) and actually find cadence (and power) to be VERY accurate (regardless of which ring in the front or cog in the rear) when compared against a separate sensor or power meter. It does sometimes take a couple of revolutions for cadence to register properly and will not be of any use when doing cadence builds/holds where my cadence exceeds 135 rpm. I find if doing relatively steady state efforts that the Kickr reports cadence very well.
If you have an '18 or earlier, then I’d suggest making sure you calibrate every couple of weeks (after at least a 10 minute warmup) and also be sure you have the most current firmware.
So questions for you:
What version of Kickr?
Do you have the latest firmware?
Do you regularly do a spindown calibration? (if required depending on your Kickr model)
What apps are you finding the cadence is off? SYSTM? Zwift? Head unit? Others? And is it off on ALL apps or just one?
Also, if possible, can you use the bike with the Rally’s on them, and dual record a workout where the Kickr is used to report power on one app, and the Rally’s on another?
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Thanks for your answer.
I own the kickr v6, using Systm only. I think spindown calibration is not necessary with this setup. And as I mentioned the cadence on the big chainring changes exactly by 30 steps from 80 to 110 and only switching back randomly to 80 for a few second. Best idea is really to attach my Rally wattmeter to the bike in the Kickr and measure independently the kickr effort with Systm and the pedal wattmeter with garmin connect. I will let you know the results.
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correct. And are you on the latest firmware @Nikosap?
In any case, it might also be worth a check in with support 
They may have a suggestion or two.