Gradient associated variation in resistance during ERG on a Kickr Bike

I’ll keep this as brief as possible.

Issue: When ERG mode is active and using a Kickr Bike, the “perceived required effort” seems affected by changes in gradient. That is to say, it is easier to maintain power on positive gradients than on negative gradients.

I noticed this when I first got the Kickr Bike a year ago and switched over to it from years of riding on a standard Kickr and then Kickr core. Neither of these other two devices seem to exhibit this issue.

At the time, I put it down to the Kickr Bike being just a little bit harder to ride – due to internal parameter settings. That is to say, I’m forced to ride a dead road on the Bike. As such, I wrote Wahoo and asked if it was possible to dial rolling resistance (RR), to which they said it was not.

Lately, I’ve gone back to doing ERG sessions and I swear this is not my imagination.

Riding a rolling scenic route while doing 2x20min with a slightly optimistic FTP, holding pace downhill is harder than uphill. The difference is slight, but it is there. This is especially noticeable when the downhill rolls into an uphill, where it is almost like receiving a small rest interval. The pedals just come over the top of the crank more easily.

The best I can guess is that some component of RR is still active within the “Zwift + Kickr Bike” that is not present within “Zwift + Kickr”. Perhaps it affects all systems, but I do not have alternative trainers with which to test.

Note: Although I use an Apple TV now, previously I experienced this with MacOS Zwift (circa 12 months ago).

Current Setup:

  • Latest gen Apple TV
  • Kickr Bike v1