Vast inconsistent difference between Snap and Assioma

I’ve been training on a Kickr Snap for a few years now. I just purchased the Favero Assioma Duos. I know that I need to start using the Assioma power readings, but as I was only about two weeks from a re-test, I stuck with the Snap power until the next test. However, I connected my Garmin 920 to the Assioma power, so I could see both the Snap power on my PC and the Assioma power on my watch. What I saw was very disconcerting.

Had I seen a consistent power differential between the two, I wouldn’t have been all that concerned. Instead, what I’ve observed is the Assioma’s being anywhere from 10 watts above the Snap to 40 watts below it. More disconcerting still, the differential seems to increase to the negative (i.e. Assioma power lags the Snap by a greater and greater margin) the higher the wattage. For example, at 200w on the Snap, the Assioma’s may be close to that. At 250 on the Snap, the Assioma’s may be at 235. 350 on the Snap may be 310 on the Assioma’s. Another thing to note is that the two can drift apart at a given wattage - for example, suppose I’m spinning along and both sources say 180; the Snap may stay at 180ish, and the Assioma’s may slowly drift down to 170, 165.

If the power differential were consistent, I would have some comfort that I was still achieving the desired training benefit, even if the numbers were off. As it is, I’m faced with the possibility that my VO2 work may have really only been high-end threshold work, sweet spot work was really tempo work, while tempo and endurance work may have really been pretty much tempo work.

I retested this morning with the Assioma’s. FTP went from 310 to 278. Sure, this is somewhat deflating, since I’ve been training hard and am likely in the best cycling shape of my life. But I can get over that - again, it’s just a number, and the shape I’m in hasn’t changed overnight. As long as the readings are consistent, I should get the desired benefit. What is concerning is that either things HAVEN’T been anything close to consistent for months with the Snap, or perhaps that it’s about to become really inconsistent with the Assioma’s.

My operating assumption now is that the Snap is wonky and my training has been suboptimal for months as a result, and I’m just going to trust the Assioma’s. Any light that anyone can shed on the topic is much appreciated.

Almost definitely the issue is with the Snap, you’re right there. However, I wouldn’t worry too much about your training being bad.

You say you’re in the best shape of your life and it’s probably true, that happened with the Snap trainer even though the numbers weren’t quite right. Could you have maybe squeezed a few extra watts into your FTP if your data was more precise? Maybe! It wouldn’t be more than a few watts though.

I’d say just start training with the new power source and don’t worry about what the Snap was saying, it got you stronger just fine.


Have you tried doing an advanced / factory spin down with the snap? Wahoo removed it from the face of the app but it’s still there - instructions can be found here -

I have assioma duos and a kickr snap and found when I started using them to be very off (roughly 75 watts) but crucially - consistently off.

I found after doing the advanced spin down the wattage the snap was reporting aligned much more closely with the assiomas - so much so that I could turn off powermatch (since turned back on)

I have a Snap 2017 and recently purchased a Quarq PM. I ran 14 tests (workouts) and compared each workout to determine the difference between my Snap and the Quarq. I used the Snap’s erg and then recorded the same ride with the Quarq recording to my Wahoo Bolt. I then uploaded both .fit files into DCR Anaylzer Tool:

After all my workouts I found that my the Snap’s Erg and the Quarq were within 1% of each other. However, before every workout I ensured the tire pressure was the same (100 psi), the roller tension was the same (2 full turns once contact with the drum is made) and did a spin down calibration after warming up the Snap for 10 mins. I also of course calibrated my PM before every workout.

I noticed if I didn’t do a spin down calibration the Snap and the Quarq were off. I also noticed some slight variations if cadence slipped out of the norm, but nothing too drastic. I posted some of my early comparison below, but since then I’ve done more tests and the power profiles have been very consistent:

I recommend doing the same type of tests and comparing the power profiles. I also played with gearing to see if the power profiles matched better dependant on what gear I was in.

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Welcome to my daily hell. :sob: :rofl:


I just found this post after getting very frustrated (again) with my SNAP and Assioma Pedals. I am going to try the advanced spin-down tomorrow.

I have another problem (at least I think it is a different one - but could be very related): If I use the Assioma PM and the KickrSnap in Erg mode, every few minutes it stops working. What I mean is: it does what I call “stalling” where you get the same feeling at 80+ rpm that you normally only get when slowing down your cadence below 40 rpm. I do a quick backpedal and then it works again. But obviously, that completely disrupts the training. This does not happen if I use the resistance mode. However, if I use the resistance mode, I have to change the resistance when I do intervals because I cannot pedal 110+ (I know some of you can but I can’t - not for 5+ minutes at a time).

I am quite frustrated and have started looking at wheel-off trainers. It might be worth giving up on the SNAP and buying something more reliable (but what?)

Do any of you have similar experiences? Did the advanced spin-down solve this?

This sounds like it’s likely to be due to a momentary signal dropout issue. Not enough to disrupt the power data, but enough to throw the resistance of the trainer. I have experienced similar with my Assiomas and my Tacx Vortex.

Are you on ANT+ or Bluetooth? I would look at the advice out there on troubleshooting device signal issues. This is a good starting point:

There’s plenty of other sources of advice that go into more detail too. Trainerroad support have also been very helpful on this topic for me.

I tried this morning but could not find the advanced spin-down in the app. I use an Android phone and the instructions on the link do only work up to step 4. There is no little radio icon on my smart phone :frowning:

Anybody know where to find the factory spin-down on the android app?


This might be what you need for Android.

Thanks!!! I will check it out tomorrow morning.

Is power smoothing “on” on the Snap. If so, turn it off and welcome to the real world of power. That smoothing is a Wahoo thing because rolling averages cannot deliver those vertical power shifts between intervals.

My kickr snap does not have smoothing on, but I did a check today against Assioma duo pedals and it definitely smooths the data a lot. I speculate that this might be due to momentum of Kickr Snap flywheel versus more direct and instantaneous readings from pedals.

The Snap is junk imo. I will be sending mine back asap.

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Snap works fine for me, since I have a Vector pedal to read from.

Otherwise the power reading from the Snap is, in my opinion, virtually worthless. Oh, and no number of spindowns has even made a difference. That is a joke too.

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