Wahoo v Zwift Spin down?

Hi guys,

Which spindown is considered more accurate when using a bike on a wahoo kickr core?

When I first started riding my average watt output for 20 mins on relatively flat routes was 230w. However, when I performed a spin down using Zwift my speed and distance performance dropped significantly. I struggle to almost get about 130w on a 20 minute relatively flat ride with a few hills. I am 25, 70kg and relatively fit.

Just wondering if my speed and power is an illusion and there is something I am missing on the setup?

I have added three photos covering different measurements I have done.

Photo 1 - Yorkshire is my performance after the Zwift spin down.

Photo 2 - A race I did after a wahoo spin down.

Photo 3 - Cycle I did in London on a Brompton with loads of traffic lights.

Any help would be greatly appreciated.

Based on your speeds I don’t see an issue with the power output but personally I would recommend doing trainer calibration using the Wahoo app. Make sure you’ve warned it up, make sure your trainer software is up to date and then do a calibration.
After you’re done make sure you completely close the Wahoo app else Zwift may not connect. It’s a Bluetooth thing.

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Well, I certainly see the difference of the 2 calibration techniques: 243 watts vs 95 watts.

I think you mislabeled photos 1&2. (photo 1 is Crit City and photo 2 is Yorkshire).
You don’t have a power reading for outside so we have to look at courses and speed.

Your IRL ride has you at 4.8 miles over 21 min with 82 feet elevation and 13.5 mph.

Wahoo ?? crit city race (243 watts) 7.5 mi, 17 min, 328 feet and 25 mph.

Zwift Yorkshire (95 watts), 4.8 miles 22 min 413 feet 12 mph

I would say of the two, the Yorkshire ride most closely resembles your IRL performance.
This conflicts with the usual adice that it is best to use the calibration app for your specific device and not use the Zwift calibration.

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I don’t get any spindowns to work well with either Wahoo app or using Zwift
With Wahoo app, it works, sometimes, but many times I never ever get the “finish” prompt. It just stays at 0 kph. If I close th app and go back into spindownwindow, I may some times get the “finish” message, sometimes not. Sometimes perform a new spindown and then it may work. Very stochastic behaviour.

When I try to do spindowns with Zwift, the actual spindown process works fine but after it is done, it is like pedalling on air. Like it’s on the lowest gear and I need to go 150 rpm just to get 80 watts out. All resistance is gone.

If I close Zwift (on PC) and start it again, then it feels like normal again when cycling

Wahoo App on Android
Zwift in PC
Bluetooth connections

Confused and makes me very reluctant to make any spindowns on any platform, since it just gives me a domino effect of wierdness

Am I the only one with these kinds of issues?

Certainly not normal.

Don’t use Zwift spindown - only use Wahoo app. Make sure Zwift and any other app that can control your Core is off (Garmin Connect for eg). Power the Core off/on and then load app. You can also play around with wheel circumference in the app to help hit the target speed.

Thanks

I never have any issue to hit either Wahoo or Zwift target speed, during normal conditions.
Only after a Zwift spindown the bike turns into a toy-bike and it’s like spinning on a 1 gear 17" bike
Restart Zwift and all normal again.

So strange Im alone with these issues, running on Intel/Windows10 and Samsung/Android, that must be the most common HW/SW combos in the world :slight_smile: