My KICKR Snap power is way off


(Cédric Liénart) #1

Hi all,

I’ve been using Zwift with my Kickr Snap for about 5 months during winter and was very happy with it! As spring arrived, I stopped my Zwift subscription, bought a new bike and went outside. The weather became rainy again so I decided to renew my Zwift subscription. Only this time, I couldn’t complete any workout as the intervals were suddenly way too hard !

In the meantime I bought a Garmin Vector3 powermeter and was able to confirm that there was a 30-40% difference between the Snap and the Vector. 100W in Zwift (as reported by the Snap) was equivalent to 133W on the Vector; 200W (Snap) vs 270W (Vector).

I did an advanced spindown and got a brake factor of 1.0 (which is the recommended value). The Snap is connected to Zwift on my desktop via an ANT+ USB extension cable. Same setup as before. Vector3 connected to Garmin Forerunner 920XT via ANT+.

Wahoo support told me to tighten the tension knob until I get spindown times closer to 15 seconds but in the past I had no issue with spindown times in the 25 seconds range. When the tire touches the roller, I tighten the resistance knob 2 complete turns and I have no tire slippage afterwards. The tire pressure is 120 PSI, as recommended.

1/ Has anyone experienced something similar ?

2/ I read that Zwift now supports power matching in ERG mode, so should I set my Vector 3 as power source and Snap as controllable unit ?

3/ Should I return my Snap and have it replaced (I’m pretty sure I would have to pay for the shipping, and given the weight of the Snap, it’s gonna cost a fortune, so I would prefer if I could avoid this !)

Thanks in advance for your help !


(David K) #2

I noticed a couple of concerns. I found a few instances where you had paired your Garmin Powermeter as a cadence sensor and kept your Wahoo paired as both Power and Controllable. That would certainly cause inaccuracies in the readings on your Garmin.

The next time you ride, try pairing your Wahoo as Power and Controllable. Try to keep your Garmin disconnected. Pick out a workout, but once you’re in the workout noticing irregularities, would you mind checking the action bar at the bottom of your Zwift screen and see if toggling on or off ERG mode normalizes things a bit? You should also be able to toggle it from Zwift Companion too.

If ERG mode doesn’t seem to be the issue, please let me know so we can open an email support ticket for you and research the cause a bit. Without figuring out what’s going on first, I don’t feel confident asking you to return anything. I’m not so sure anything is defective.


(Nigel Doyle) #3

Return it for a refund. I had the same problems you had. Wahoo support were appalling and blamed my 4iiii power meter. I now have Favero Assioma power meter pedals and these match the 4iiii so the problem was definitely the Snap. I’m now using a  Hammer trainer.


(Cédric Liénart) #4

So I’ve progressively turned the tension knob from 2 full turns to 3.75 turns in order to decrease the spindown time from 26 seconds to 12.6 (within the 10-15s recommended range) and performed a new test with Zwift and my Vector3 pedals. The results are better, but still the Snap is on average 10% lower than the Vector3. Furthermore, turning the tension knob almost 4 full turns is twice as much as before and presses hard on the tire. Somehow, I still feel there is something broken here…

@ David K : I’ve tried toggling ERG mode on and off but I always have a difference between the 2 power readings. Also, since I don’t have a separate cadence meter, I have to select the Vector3 as the source for cadence. The Snap is always set as Controllable and Power source. Why would this cause inaccuracies ?


(David K) #5

I’m thinking it’s probably best to turn this post into an email support ticket and get Wahoo involved for you. Please catch up with me via email when you have a moment. Thanks for your patience, Cédric.