I have been using the power from my Tacx Neo 2 for my TR workouts. I currently also have Garmin Vector 3 pedals on the bike which display on my Garmin Edge. There is a significant power discrepancy between the two, about 10% (187W on the Tacx reads 209 W on the Vector 3). The bike on the trainer is not the bike I use outside, it is an older road bike.
I have performed a torque calibration test on the Vector and they are accurate to 0.3%. The power displayed by the Vector matches the performance predictions on online performance prediction tools on long climbs so that confirms the accuracy of the Vector pedals. There is some loss in the chain and pulley wheels but it can’t be 10%. There is no way to adjust the Neo 2. I have re-waxed the chain and will see how much that narrows the spread.
My FTP is based on the Neo 2 power data. If I go outside TR AI is going to think I am doing some monster workouts and adjust future workouts in response. I’d prefer not to adjust the (accurate) Vector 3 readings downward to match the Neo 2 numbers. What is the best way forward?
Really wish TR had an option to have indoor and outdoor FTP settings
Is it the Neo 2 or Neo 2T? I don’t know about the Neo 2, but a lot of people experience the 2T reading notably lower than their pedals (myself included). I just don’t bother with power from the trainer. I use Power Match indoors, and outdoors is obviously just the pedals, so it’s the same measuring device anywhere I ride. As GCN found out recently, 200W into the pedals is 200W into the pedals.
I don’t know which Tacx trainer this person used, but they saw similar numbers to you.
It’s a Neo 2. I have a Neo 3M coming next week. I’ll see if there is a difference. I’m skeptical that a clean waxed, Dura Ace chain deteriorates enough in a clean indoor environment to consume 20W of power while still measuring about 0.25 on stretch
When I see reviews of trainers or power meters, they usually run several at the same time (pedal, crank and trainer) and the results look a lot closer together than what I am seeing.
Sorry to hear that. My n = 1 dual recording tests with two different sets of dual-sided pedals has my TacX Neo 2T typically read about 0.5% difference. Also… it took 45min of steady 252W (at the trainer) for a just-waxed-and-still-stiff chain to stabilize at 254W at the pedals; at 25min it was still 256W pedals vs. 252W trainer). Context - I did a 2 hour dual-recorded ride at 252W erg to check how long it took for a chain to become “fast”.
The same chain/bike did a 2 hour outdoor ride with 4x6min hill repeats for the next ride, and after that it was 253W at the pedals for 252W into the trainer (could be margin of error, though).
I rode today after waxing the chain. The variance was 13W an improvement of 9W in the spread. I have a Neo 3M coning this week for a second house in AK. It will be interesting to see if the Neo 2 and Neo 3 have the same variance from the Vector 3 pedals. I think I can live with a 13W spread if need be
This is the pickle we run into when multiple power meters are used. That’s why we recommend using PowerMatch.
However, the good news is that TR won’t spike up your future workouts if you use a different power meter outside. If you complete a TR Workout outside, then you will get the Workout Level credit assigned to that workout and the plan will adjust accordingly.
Then as far as AI FTP Detection goes, I wanted to mention that it analyzes millions of rides, to understand how FTP changes over time and in response to training. So, doing a mix of outside and indoor training with different power meters should not be a deal breaker.
Let us know how the Neo 3M goes! But just know discrepancies between power meters are only natural.
