I have been using XERT with 2 sources of power data. For riding outdoors I use P1 pedals and it seems to give good data and work well. I also use it for indoor training using a lemond revolution, with virtual power recorded using a speed sensor on the flywheel and trainerroad. I have been doing this to save wear on the pedals and the (admittedly minor) hassle of changing them. I have observed that the pedals record power about 15-20 watts higher than the virtual power. Virtual power will also assume a steady state and therefore will underestimate power when you are accelerating and overestimate when you are decelerating as the speed of the trainer declines. The result of this seems to be that on indoor sessions imported into XERT I never seem to come anywhere near my MPA - although I know I have been broken and done sessions I could not complete.
Ideally I would prefer to use virtual power for the indoor sessions. Is there a way of using two different fitness signatures to cope with the two different pieces of equipment?
Thanks for your advice.
There is some planning around how to allow scaling of power data from different sources. It’s on the roadmap but a bit further down the list at the moment, TBH. I wish we could bring everything forward on the schedule!!
The whole value of P1 pedals vs. other power meters is the interchangeability. I use that alan key 2-3 times per day!
Thanks for the replies. I think that the product is great and am looking forward to the ios apps. I would also love a MPA field on my garmin 500, but may be forced to get a 520.
I think that the incorporating virtual power from trainer may be more difficult than a simple scaling issue as the peak power would always be underestimated as even if you accelerate hard for a few seconds at 1000 watts you will only get the power output of the corresponding to that for the highest speed you achieved at steady state. I presume that with the raw data some clever people (Baron biosystems?) could look at the upstroke of accelerations and decelerations and estimate the power from gradient of the speed curve.
The p1s are great but mine did need repair at one stage and I almost died doing sessions on virtual power with the same FTP.
What did you need to get repaired with the P1s? I have had no issues, but it’s always good to learn about what can go wrong.
One pedal developed some play on the spindle and they would not calibrate. Got replaced by supplier on warranty no problem. You cannot repair the pedals as you would a normal pair so I am keen to avoid wear on the bearings.
If you want a virtual power solution that works with Xert and any other app that reads ANT+ power, have a look at my open-source project: https://github.com/dhague/vpower. It uses a Raspberry Pi to read the speed from your trainer, do the maths to calculate virtual power, then broadcasts that as an ANT+ power signal.