Originally Posted by
chaadster
Is it? Could data sampling rate differences be having an effect? If the fast Race Mode option is enabled in Wahoo but you’re not connecting to Zwift app via wifi or DirectConnect, would the bike record natively at high sampling rate but Zwift still receiving at lower rate? Depending on which data packets made it to Zwift, it would be working with a different and incomplete set of data than Wahoo, right? Particularly when effort level is quickly variable, like a brief surge up a roller, there’s more opportunity for discrepancy between data sets. I dunno…but Race Mode is supposed to improve responsiveness in Zwift by minimizing data gaps from the trainer’s PM.
Even outside of Race Mode, wouldn’t a slow ANT+ connection to Zwift show data packet variance compared to the Wahoo recording (via Bluetooth to the phone)?
Wahoo also has the power smoothing feature for ERG mode, which if you have that on, may also be a factor.
I thought about sampling rates, but both Wahoo and Zwift are receiving data at 1 Hz via Bluetooth connections. I have Zwift connected through my laptop and Wahoo App connected from my phone. My Kickr Bike doesn't have DirectConnect for the Wahoo 10 Hz option.
I need to overlay the data sets (which I can't do directly at the moment) to see how the power data actually compares sample by sample. From what I can see looking at the Zwift data is that if I stop pedalling it holds onto the last recorded power and cadence for about 2 seconds before dropping to zero. But if I pedal continuously the data changes every second as you would expect. Zwift is definitely applying some sort of time lag whenever cadence suddenly drops or I soft pedal for a few seconds. It's not dropping data packets otherwise the drops would be completely random, which they are certainly not. If I pedal at a reasonably smooth cadence, I can see the power changing every second as expected.
The effect this has on average Zwift recorded power over rolling courses is a bit of a joke to be honest. The Wahoo recorded power data at the same frequency, over the same BT connection, gives a much more realistic power average in line with outdoor rides.
Edit: Also note that the average recorded cadence is identical in Wahoo and Zwift. It is just the power average that is significantly higher in Zwift.