Kickr Snap Power wildly off

I did the advanced spindown and yes I calibrate every time I ride.  I have had a Stages power meter and Power tap so I know what power i output. With Zwift and the Kickr, my power is a little over 1/2 normal.  Yes my weight is accurate.  Yes the wheel pressure is adjusted.  I’m bummer because I really wanted the Kickr and Zwift but looks like I’ll have to return it.  

Hi Ken. Seems strange I have the same trainer and it is reasonably accurate in comparison with my power meter. Are you pairing the snap (power and controllable trainer) with Zwift as the ANT+ FEC option.

If the above makes no difference it might be worth checking the snap with a different head unit other than Zwift (such as a bike computer) and pair your separate PM with Zwift and compare the readings? 

Hi Ken

I reflect what John has said above to rule out a problem with the trainer.

I would also try taking the ‘trainer difficulty’ to maximum to check Zwift is communicating OK.

What sort of reading are you getting and what would you think they should be?

Similar problems to what I had with a Kickr Snap and power way off what my power meter reported. Things got worse as the power target or resistance increased and the gap between the Snap and my power meter widened. e.g. 200 watts on Snap = 250 watts on the power meter, 250 watts on the Snap = 350 watts on the power meter. 300 watts on the Snap locked up the back wheel. I exchanged the Snap and the replacement was just the same. Ended up getting a refund. At the time others also reported the same problem. Seems people like me using Android devices to calibrate have had more problems than people using ios devices.

Wahoo support were appalling when they could be bothered responding to me and said my power meter must have been faulty. I upgraded my power meter and my FTP stayed the same. I now have a Hammer trainer and power is close to my power meter.

Personally I would take it back for a refund and get a direct drive trainer. These then don’t require spindowns every ride and after they’ve been warmed up.

Ok so here goes.  I’ll try to explain a few observations but I do not yet understand all the connection type. I’m far from an idiot, not more ignorant of the system at this time.  

1.  sometimes Zwift sees my Stages PM and allows me to pair it as the “power source” .Sometimes not.  Should the Stages be my primary power source if it allows it?  Is it usually better practice to select this rather than the “Wahoo FE-C”?

2.  Sometimes I can pair my Stages as the Cadence device, sometimes not.  My ANT dongle is VERY close to the Trainer. Is the cadence feature helpful and is it best practice to use it?

3.  When I look at the workout list, I have the use ERG mode selected. I suspect this is a better option and will help ensure I am using my Stages PM corrct?

  1. I am on a Carbon hard-tail MTB not a road bike. I have a 1X11 with a 32/10/42 XX1 setup.  Is my lack of taller gearing affecting my ability to lay down more power? I did the first two Beginner FTP builders and find I am spinning out too high at times. I also adjusted difficulty to 100%. Is this a helpful approach?

  2. My typical FTP score from both my current Stages PM and a previous Power-tap is around 328.  I am 6’2 and weigh 210 currently. When I race XC I try to get under 200. On the Wahoo with Zwift it shows my current FTP at a wimpy 237 but I have not done an actual FTP test yet. I have had a 3.65 W/kg score in the fairly recent past. I am 56 years young and like I mentioned I race part time and like to climb a LOT here in So-Cal.  Any feedback is appreciated.    

Please disregard the typos. I usually well-spoken but I’m a bit tired from NYE!  

  1. Normally selecting a power meter in preference to the trainer is the best thing to do. You are waking the Stages up by spinning the cranks first aren’t you?

  2. Sames as #1. Wake up the Stages. I use my 4iiii crank based power meter as the power source and cadence source. If it’s not showing up, spin it while Zwift is searching.

  3. ERG mode locks you into the target power. With Stages as the power source it will be used to control the power target / resistance of the Snap. Usually the best way to do workouts.

  4. If you’re doing a workout in ERG mode you don’t change gear. The trainer will adjust to the target power. If you’re free riding you may want to experiment with trainer difficulty. This is essentially the same as changing the cassette on your bike to give different gear ratios. Your power output is still the same.

  5. Do a FTP test. I’m also 56. FTP currently 307, 76 kg so just over 4 w/kg. Some of the Zwift workouts have silly power targets e.g. 100 watts between intervals so spinning too fast is very easy to do. I use Trainerroad workouts. These are better thought out than Zwift workouts. You can if you wish customize the built in workouts.

Cheers. Hope this helps.

Some good advice from Nigel. It is really up to you which power source you select. I use a seperate power meter but the one in your kickr snap should still be usable and give you a reasonable estimation of power. But technically the separate power meter should be a little more accurate and you avoid the kickr snap spindowns to calibrate the internal PM. I did use the snap internal PM for about a year without much problem until getting a separate PM in November. 

It’s a little confusing but there are a couple of options for the internal Snap PM in the zwift pairing screen. Always choose the ANT+FEC option for the power meter and controllable trainer.

Before you get started I would highly recommend completing an FTP test rather than working from an estimated FTP.

I actually do a lot of zwift workouts and think most are great, they have helped me improve a lot (an FTP of 237 watts would not be that wimpy!). The low power targets tend to be warm up, cool downs, gaps between hard intervals or maybe the workout selected is not just for you (there is a massive choice these days).

Take a look at the following site as you can search for 694 custom and zwift workouts at the time of writing:

Hope this helps Ken.

Thanks all for the suggestions.  I cancelled my Zwift account. It seems there is a lot of issues with it.  I will use it till my subscription ends later this month but I suspect there are better options.