Spin down calibration "resistance" or lack there of

Equipment
1

Is there a way to increase the resistance when doing a spin-down calibration? I tried putting it into resistance mode and standard mode (with Wahoo Kickr) but it seemed to go back to a default. Is the “resistance” the same for all users or is it set based on FTP? My partner looks like she’s going to fly off the bike she has to spin so fast and can often not complete the calibration.

2

No way to increase resistance I know other than shifting to a higher gear on the bike (assuming that’s possible and you’re not using a single-speed or low geared bike like a MTB).

3

What he said. :point_up:

It might be worth reaching out to Wahoo if they can’t complete a proper spindown because of this issue…

Most KICKRs do auto calibrate now though, so it might be worth doing a short workout (~30 minutes) to see if that helps…

@grega What model KICKR do you have?

4

It is an MTB… but I suppose we could shift to the highest (which its not in) then back after calibration but seems odd to do so.

5

…could also throw on a bigger front ring too I suppose…

6

Not when you understand the basic needs of a spindown calibration.:

  1. The key requirement is to get the rear axle spinning to the required speed, which is around 20mph for most trainers I have seen. This sets a baseline to get the flywheel and trainer guts moving to a known “speed”, that they then use to evaluate reduction in speed over time to estimate the system friction that is used in the power data estimates.

  2. They keep the resistance low because it is not needed for the calc, and it’s actually intended to be “Easy” so people can reach that speed with less effort.

  • This is standard procedure IMO. There is no requirement to be in your ERG training gear for calibration (a common misconception). It is most important to get the axle speed and as such, a taller gear is best.
2 Likes
7

A spin down calibration is used to measure residual friction in trainer, which needs to be subtracted from the total power measurement. Adding resistance would confound what needs to be measured.
Wheel-on trainers have considerable and highly variable friction between the tire and roller that depends on the tire, pressure, and tire temp. For good accuracy, a spin down calibration should be done after a warmup and before a workout. For direct drive trainers, there is much less friction and it is much less variable, so calibrations can be done infrequently.

1 Like