Ok, looks the following has worked for me… so here goes it may help some people.
If you receive significant power spikes/drops in Zwift when using a Wahoo SNAP and ANT+ connectivity to Zwift complete the following:
Follow the correct spin down and advanced spin down procedure recommended by Wahoo including the correct resistance of the roller to the rear wheel. All this info can be found on their site or from their support team.
Test using the Wahoo Fitness App in IOS or Android. This uses Bluetooth so can help troubleshoot whether its an ANT+ issue or possibly the trainer.
If the power remains relatively steady in the Wahoo Fitness App (there is always some small variance unless you are super steady on the pedals), then goto Step 4.
If there is still significant variance contact Wahoo Support, or you could try what this chap has done (https://www.youtube.com/watch?v=Qp9w8bLIYpw). This has solved quite a number of peoples issues.
Use a laptop or PC with just bluetooth using your IOS or Android device as the BLE bridge with Zwift mobile link app.
As you had relatively steady power figures through the Wahoo App you should see the same result now in Zwift. If not it could be an internet connection issue. May be worth calling Zwift at this point if there is still a problem in Zwift.
Assuming everything worked ok with bluetooth and Zwift, now look at the following when using ANT+ and Zwift
- Remove all other USB devices where possible (eg wireless mouse, BLE headsets etc).
- Zwift only works with USB2.0 so if you have an old garmin dongle (it may not work).
- Ensure if you are using a laptop it is powered and not using battery
- Check USB ports are not configured to go into power saving mode
- If you PC/laptop is more than a few feet away from trainer then get a decent USB extension cable. Then run the cable from the PC/Laptop all the way to the trainer.
The above has worked for me. It ended up being a combination of laptop power and other USB devices plus the need to run a 10ft USB cable.
Hope it helps.