P1 pedals, kickr, Garmin 820 and Zwift

I read some of the other posts about P1 pedals but not sure they really apply. I have a Wahoo Kickr, P1 pedals and a Garmin 820.

I am sending my data to Strava and Training Peaks (for my trainer). I have found that the wattage on zwift is consistently 20% and sometimes 30% lower than the readings I get on my Garmin with the P1 pedals. I generally load my days training into zwift to apply the resistance necessary. I find that I have to start off riding to see where the difference is for that day then adjust the ftp in the workout to get the desired output on my Garmin. 

I can’t use the zwift to document the workout in TP because the readings are consistently lower.

Is there a way to get these units to mesh within a couple %? 

Why can’t you use the P1 pedals for both Zwift and your Garmin? With Ant+ you can connect to multiple devices at one time.

I am going to take a guess on why you are not and it is because you are using a Mac or iOS device and are using Bluetooth to connect the trainer to Zwift. If this is not that case and you are using an Ant+ dongle then I would just connect the pedals to both Zwift and the Garmin.

I am using a PC… why do you need the P1 pedals for zwift? The power on zwift is generated/measured by the resistance on the kickr. You would link both into zwift?

Which does zwift read for watts when you have the kickr AND P1 pedals linked?

If you are using the Zwift Workout module for your workouts then the trainer is in ERG mode and the elevation changes will not be transmitted to the trainer anyways. 

If you are using Zwift Workouts then I would just connect the P! pedals to Zwift and the Garmin so you get identical information. 

It has been requested many times that smart trainers should be controlled via external power meters (ie you P1 pedals) as of right now that is not possible.

I just purchased a power meter for my bike so I can have more consistency between indoor riding and outdoor. If you are seeing a 20% to 30% difference I would go for consistency and use the same power meter for both types of rides. After over a year of using Zwift I am very suspect of the power readings of any trainer within Zwift. Yesterday I compared my power meter (4iiii precision) with the power meter on my trainer and it was close to 50 watts difference. 

That is why I start a training session to see where the difference is between the two, close it out then restart it after adjust the zwift ftp to get the desired reading on my Garmin. The Garmin is the only thing that loads to TP for training purposes. I’ll try linking the pedals as well and see what happens. Thanks.

I have P1 pedals, a Neo, a Kickr I, Kickr2, a Drivo and they all measure power differently. Some by a very significant amount. Zwift is a game, but a very useful one for motivating you to ride hard. It is not, and never will be a level playing field. 

So far, I like the Elite drivo best… It’s got a very nice smooth pedaling feel. 

There’s a feature in the Wahoo Fitness app that lets you set the Kickr to read power from an external ant+ power meter.

So, if you set the Kickr to read power from your P1 pedals, then pair just the Kickr (and not the pedals) to Zwift, that should (theoretically) solve the problem.

I’ve been using Vector pedals with my Kickr and it does seem to work.

That is fascinating.  Paul Allen, see you got the 4iiii crank arm.  HOpe that is working out.  I swapped to deciding on the P1 pedals.


But Josh, if what you are stating is correct, you may have found the holy grail for me as I would prefer that for power readings my P1 pedals are used even when doing work outs in ERG mode.  Perhaps if I have my power reading routed thru the KICKR and then claim the KICKR as the source for power, then this will allow me to use ERG mode with P1 pedal readings for setting power versus the KICKR?


Be a great work around since you can only right now use ERG mode if the smart trainer is both power source and trainer source.

Yes, that’s the idea.  Seems to be working for me.

Curious, have you confirmed this by running another app on your iphone for example (Powertap app) to see that the #s are matching up between what it is reading off of the pedals and what Zwift is claiming to be coming from the KICKR (in my case the KICKR Snap)?

I have to do a ride later today so love to get this set up.  Though I fear that means my current “claimed” FTP once I do things right will drop since I think the pedals show about 10 watts or so differential from my KICKR Snap readings.  Sort of deflating, but hey, if it works, all good!

Oh one last question - did you only have to do this once, or do you have to constantly set the KICKR to get its power from the P1 pedals each time you start a ride?  Be best if we could set and forget I guess.

Yes, I’ve confirmed it by running multiple apps at once.  The Kickr smooths power readings in its default settings, so there’s still some variance.

You probably will see a lower FTP, and increased workout difficulty at the same nominal FTP, for better or worse.

You only have to set it once.

Well, I did it this eve and I think it is working.  At higher wattage I feel the measure shown on Zwift is very close to what my Garmin is showing (which does 10 second sampling), but at lower wattage I still see a discrepancy between what the Garmin indicates versus zwift.

I wish there was a way to confirm in the wahoo app that in fact it is picking up my pedals.  I had to put in the ID of the pedals, and I think it is working, but if there was just some feedback confirming it is picking up the readings from the ANT+ device being referenced and that there is a read from it, that would be perfect. When I turn off the option, which I thought would cause power to go to zero, it did not which gave me a bit of a pause.

That stated, this was a far tougher workout this eve…!!!

As I researched that Kickr option, people on other forums were saying that the app actually does indicate whether it’s reading the outside power source.  There’s a little dot next to the signal strength bars on the Wahoo Fitness app.  Apparently it’s green if there’s a connection, red if not.

I haven’t tested that, but I do think the Kickr is reading power from the pedals.  I had to drop my FTP by 30 just to get though the workouts after making the change!