When using my power meter as a power source with ERG mode the watts aren’t being held and are all over the place when I increase and decrease cadence. However when I use my Kickr Snap as a power source the watts are held as they should be in ERG mode no matter what cadence I am at. I’m looking to get into the workout side of Zwift and want the best possible accuracy with ERG mode working correctly at the desired watts. Is this a common issue when using a power meter with WRG mode?
I have no idea about Kickr Snap, but it is not a common issue - I have no issues in Erg mode, using P2M powermeter for power and cadence.
Craig, I use Wahoo Kickr Bike, but Wahoo Fitness application should be the same. Somewhere within this application (which you run on the phone), there is a configuration slider which turns on 3 seconds power averaging. A similar slider is available in Zwift. If this slider is turned on, power readings are very nicely smoothed. If it is turned off, noise and fluctuations become quite a bit higher. Obviously, when you use third-party power meter, you do not use power smoothing in Wahoo device, and this could lead to a higher noise in power, as reflected on Zwift screen. From what I know, Kickr Snap power readings are calibrated and quite accurate, I doubt you would gain much, if anything at all, from using an alternative power meter (other than ability to do a higher level of analytics, if your pedals with power meter allow measurements of force vectors, etc.).
I’ve done two Zwift 1 hour workouts since my post. I used the turbo as a power source so ERG mode was working correctly but also logged the ride with my power meter connected to my Garmin. The live readings from the power meter were pretty much bang on with the Kickr throughout the ride and at the end of one ride the average watts from the Kickr and the power meter matched exactly and at the end of the other ride the power meter average was 1 watt higher than the Kickr. I’ll continue to use the Kickr Snap as power source for workouts as it is pretty much giving the same readings and average as my power meter.