Snap with External Power Meter? Calibration Necessary? Thanks so much!

My friends, hello and good evening. Thank you so much for reading this. First poster here.

I have a Wahoo Kickr Snap, and I like that it reacts to terrain changes in Zwift, BUT, I dislike having to calibrate it every time I ride it.

Can I connect the Snap as my controllable trainer, and a power meter as the power source, and then not have to calibrate the trainer? My rational is that if the separate power meter is giving Zwift the data, then the Snap does itself does not necessarily need to give perfectly accurate numbers?

Would this proposal work? Based on what I’ve read, I believe it will; however, I wanted to ask you fine folk just to make sure before I buy a separate power meter.

Thanks, and very best regards,
DJP

This should work, but some power meters also need calibration. Either way a power meter will likely have more accurate power readings. Welcome to the forums btw!

Hello! Thank you so much for the quick and helpful reply! And your warm welcome was just great!

I hope you’re have a fantastic evening!

Very best regards,
DJP

Many people who own trainers with substandard power reporting do this (eg, Stages SB20 + Assioma pedals)

Sure…I used to use P1 pedals as the source and the Snap as controllable. The P1s require a calibration every use but I rarely calibrated the Snap. Usually on big climate changes or if the Snap started acting up. In either case, not often.

This is great to hear! I am so glad that other people have found this solution to be useful - Thank you Paul, Chris, and Oliver! I am not very good with the technical side of bikes, and I am frankly even more backwards when it comes to the technical side lol. So I really appreciate people helping me understand this!!

Thanks again all, stay true, and very best regards,
DJP

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Just be aware that you lose the ability to dual record or compare…I am not aware of a method to independently record the actual power of each device. There might be … but I would think it would be difficult. Not an issue unless you are doing Pro-level and need dual recording. At that point, you probably would not be using a Snap.

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Thanks for the input, Chris! You’re right, no pro-level yet (but here’s hoping in the future lol!!)

Stay true,
DJP

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Why should he? He can use any bike computer, another app (for example Jepster for Android) to record the power from Snap.

Hi Daniel
As other Zwifters have highlighted here, you sure can.
I use my Stages PM as the power source. I still have to Zero the Stages, but it is a lot quicker than warming up the Snap and tyre. The only issue is if the Stages battery goes flat during a ride/race (which happened yesterday).

Is it independent or just rebroadcasting what the power meter is broadcasting? I have not tried this setup nor do I recall reading about anyone doing it this way. Although I would think DCRainmaker or Shane or someone would have tested.

Maybe I will try it one day.

It is easy!
My setup is Tacx Neo and P2M Powermeter, both sending ANT+ and BLE (your Snap too). I use Tacx as controllable, P2M for power and cadence - that is the fit file saved by Zwift. That means I need to record the power from Tacx. Not sure if I could pair Tacx for power when it is paired with PC BLE, but I believe that is not possible. But I can record with an ANT+ device - for example Garmin bike computer or a phone with ANT+ and an app - Jepster is perfect for me. I used my old HTC U11 (built in ANT+; I had Jepster and Zwift Companion running on display). You can use an USB to ANT+ adapter, too.
Another way - Zwift on PC with ANT+ adapter, BLE bike computer (Polar for example) or any mobile phone with Jepster BLE.

Is free, but for Android only!

Depends on your setup, I tested all possible combinations, had never problems.
By the way - P2M and Tacx Neo (1st gen) were never more than ±1.5%.

Ride on!

The connections are not the issue…my question is why connect in that way?? I think (but need to verify) the UCI/Pro/HiLevel dual recording is separate PM and its own recorder. The Trainer has to source and be controllable. Also note that I am not starting any Pro level races…not going to get there:-)

Connecting with separate PM to a controllable trainer, and then the trainer broadcasting power to another reading device…will this give you essentially the same number? What is the accuracy difference between the two schemes?

The actual mechanics of the controlling scheme might have to be delved into…but it might just be a 30 minute tests between the two connection schemes.

Hi @chris_benten1

You don’t need to connect the trainer power to any other apps. That is only for dual recording and as you said you are not riding pro races.

Pair your Power meter as power source and your trainer as controllable optional you can pair your power meter as cadence as well.

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Gerrie,
I get the connections. I currently do to check the calibration of my H3 (P1 to Garmin F3; H3 to Zwift via BT as source and controllable).

I GET IT.

My question is about the different connection schemes. And sorry for taking this way off topic but sort of related.

I need to draw a couple of PFDs as apparently my words are incomprehensible.

Sorry I thought people was steering you towards Duel recording when you did not need it. :slight_smile:

Yes if you need to check the calibration then you need another device to record the secondary power meter.

Option 1:
Connect Trainer H3 as power and controllable to Zwift (Ant+)
connect P1 to garmin F3 (Ant+)

Option 2:
Connect P1 as power and H3 as controllable to Zwift (ANT+)
Connect H3 to Garmin (ANT+)

the nice thing about ANT+ is you can connect it to multiple devices.

So…my question is on Option 2…Is that legit?? Or does the trainer just rebroadcast what it is supposed to be at from Zwift’s direction? In other words, is just the same signal in a loop?

No.

The trainer will broadcast the power it measure. The H3 always broadcast the measured power even in ERG mode.

Trainers don’t like option 2 for ERG especially if there is a big difference between Power meter and trainer measurement. But this does not impact accuracy during races.

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I think Chris’s question is ,“what constitutes dual recording?”
I think option 2 would not be dual recording because the 2 devices reporting power are reporting the power from the same device.
I assume they would be exactly the same.

EDIT
That’s not option 2.
But a senereo that I describe would not be dual recording.

Duel recording is recording two independent power meters.

I don’t see a problem with Option 2.