Murray,
First of all, thanks for addressing the issues. I'm looking forward to see what effect the new firmware has.
Can I ask you to clarify a few things in the above ? It's not quite specific enough for me to understand fully what you mean.
I had previously understood 'linking 3rd party power meters' to mean that the KICKR used that external PM as the basis of its decision to increase or decrease resistance. For example, if the workout software (e.g. Wahoo Fitness) asks for 200W, then the KICKR adjusts the resistance until the external PM reports 200W load, and *completely ignores* the internal PM. Here there is only one feedback loop, involving the brake and external PM. That's a perfectly valid approach, especially for those who want to use the same PM on the road.
Or does it mean that the internal firmware conducts power measurements using both the internal and external PM, and determines an offset between the two, but still uses the internal PM with the offset applied to get an alternative estimate of applied resistance which better matches the external PM. Here there are two feedback loops - a high bandwidth loop involving the brake and the internal PM, and a low bandwidth loop involving the internal PM and the external PM. This could also work well, and possibly even better if the bandwidth of the internal brake/PM feedback loop is higher than the ANT+ based external one, and the offset is measured sufficiently often to compensate for any temperature related drift (or drift for any other reason).
There's a third explanation, which I suspect (sincerely hope) you're not doing: measuring the offset between the internal PM and the external PM, and adjusted the reported power from the internal PM by the offset amount. That would mean you report a certain power value, even though the resistance isn't being adjusted accordingly - that would be misleading. Anyone with two power meters would uncover that very quickly indeed...
There may be other explanations, but I can't see what they are right now.
Presumably because said hub-based power meters need to be removed from the bike to fit it on the KICKR! Or am I missing something?
Finally, I'd also like to hear the estimated accuracy with these fixes to the internal PM. I'd love to be able to believe my KICKR's reported power without having to use an external PM.
First of all, thanks for addressing the issues. I'm looking forward to see what effect the new firmware has.
Can I ask you to clarify a few things in the above ? It's not quite specific enough for me to understand fully what you mean.
WahooMurray wrote:
Linking 3rd party power meters is not to correct the error in the KICKR, its to match the power readings. All power meters (including KICKR) have a margin of error and read power from different points in the system so we are simply offsetting the readings so they match.I had previously understood 'linking 3rd party power meters' to mean that the KICKR used that external PM as the basis of its decision to increase or decrease resistance. For example, if the workout software (e.g. Wahoo Fitness) asks for 200W, then the KICKR adjusts the resistance until the external PM reports 200W load, and *completely ignores* the internal PM. Here there is only one feedback loop, involving the brake and external PM. That's a perfectly valid approach, especially for those who want to use the same PM on the road.
Or does it mean that the internal firmware conducts power measurements using both the internal and external PM, and determines an offset between the two, but still uses the internal PM with the offset applied to get an alternative estimate of applied resistance which better matches the external PM. Here there are two feedback loops - a high bandwidth loop involving the brake and the internal PM, and a low bandwidth loop involving the internal PM and the external PM. This could also work well, and possibly even better if the bandwidth of the internal brake/PM feedback loop is higher than the ANT+ based external one, and the offset is measured sufficiently often to compensate for any temperature related drift (or drift for any other reason).
There's a third explanation, which I suspect (sincerely hope) you're not doing: measuring the offset between the internal PM and the external PM, and adjusted the reported power from the internal PM by the offset amount. That would mean you report a certain power value, even though the resistance isn't being adjusted accordingly - that would be misleading. Anyone with two power meters would uncover that very quickly indeed...
There may be other explanations, but I can't see what they are right now.
WahooMurray wrote:
Unfortunately this isn't available for hub based power meters.Presumably because said hub-based power meters need to be removed from the bike to fit it on the KICKR! Or am I missing something?
Finally, I'd also like to hear the estimated accuracy with these fixes to the internal PM. I'd love to be able to believe my KICKR's reported power without having to use an external PM.