The trainer itself is only able to adjust based on it’s own power readings; that part of the circuit we are not in control of. The portion that we are in control of is the ERG commands that we send to the trainer. So the way PowerMatch works is it monitors the two power readings, determines the offset, and then sends the adjusted ERG command to the trainer. This allows us to keep you at the Target Power according to your power meter’s readings.
Does that make sense?
Is that where, with a kickr, using an ant+ source for power it does what powermatch can’t and actually adjust the readings from the trainer?
Some trainers, including newer Kickrs, will allow you to pair a power meter directly to the trainer. If your trainer has this feature, then yes, the trainer will use your power meter as the active power source and will use your power meter’s power to control the ERG mode.
If your trainer has this feature, then you can disable PowerMatch since the power transmitted from your trainer will be the values from your power meter.
Does that clear things up?
Do you know, in case of Wahoo, where it stores this Powermeter ANT+ ID? Do you know have to keep running the Wahoo Fitness App and maybe my powermeter’s as well to know the ID and the offset?
On my Kickr 2017 direct drive it stores ANT+ power meter on the Kickr. Except when it forgets. Which happened a lot. So I had to fire up the Wahoo app on my iPhone quite often. And even then, it failed sometimes. Called Wahoo support several times and no resolution. I gave up and love TR PowerMatch it just works and makes trainer rides more like riding outside 
Hey Chad,
Great info, man.
Would it be possible for a PM to read more than the trainer at one point and less than or same as the trainer at another point?
For example, is it possible that the PM reads 290w when the trainer reads 320w but then at lower wattage (ie under 200w), both read the same at any given point?
In such cases, who would be telling the truth? What would be the true FTP?
For example, I recorded a test with a PM and a Trainer at the same time but in different screens and not paired with each other.
Trainer (BKOOL PRO 2) gave me a 328 FTP.
PM (Quarq) gave me a 283.5.
Who should I believe?
I get the comment about the tape measure, and at that time I decided to just go with the trainer and did the entire block of training without using/pairing the PM, just the trainer. But it left me wondering what my FTP really is…?
I know they say it’s just a number but I’m curious…
After the current rest week, I plan to PowerMatch both and retest next Tuesday.
For sure, that is possible. It can happen when the slope of the devices don’t match, and they have a crossover point where they actually match. On either side of that, the offset can be reversed.
As long as you use the same device for testing and training (like you did with the trainer) you should be setup fine for training.
As to the question of which is “right”, the best way is to have a 3rd power meter in play and see how all 3 compare.
But based on your devices and what I’ve seen reported elsewhere, the BKool is like not the “right” one. They suffer from a poor setup and variable roller pressure due to the gravity based design. It is a fatal flaw, IMHO and one that leads to the bad power reporting.
Again, just a guess, but Quarq power meters are much more highly regarded for data reporting and is more likely to be “right” in this instance.
Fair enough. Thank you once again for all the answers you helped me with today 
Yep, thanks @Bryce. Using the Wahoo system currently seems to work great. Had mixed success previously with powermatch, didn’t find it great on workouts with short, sharp intervals. To be fair not done one of those with current setup but a variant of Spanish needle scheduled over weekend I think so that should be a good test.
Well regardless of what method of getting trainer to provide the correct level of resistance to match the power readings of a power meter today’s Spanish Needle workout was a real eye opener regarding gearing used in erg mode.
I know powermatch was always said to work better when using a lower gear so flywheel is spinning slower but I was getting pretty reasonable raises in resistance using a high gear so left it like that until the final set of intervals. Up until this point the workout had been perfectly achievable but then I switched to a much smaller gear and boy did the workout get harder! Cadence was similar but I can honestly say I wouldn’t have been able to complete the full workout if I used this gear for the full 90 mins. So not all watts are equal - am I doing myself a disservice by using higher gearing for all my workouts? I like the feel of a faster flywheel but ultimately I’m doing this to make myself faster…
What gearing did you use for your FTP test?
Regardless of your gearing choice. I think it’s best to test in the gearing that you plan to use in training, at least most of the time.
I also think mixing the gearing in training is also good, and have been mixing more frequently this season.
You’re using the terms lower, higher and smaller gears which makes it confusing. By smaller gear are you referring to a smaller cog on the cassette and thus a higher gear? Also what ring are you in on the front. Probably easier to understand if you give your gear ratios instead.
When using Powermatch, do I need to calibrate my Kickr and Power2Max power meter before each session?
We’ve seen “Yes” and “No” answers. Ideally, Power Match will adjust for any variation. But some people claim better results with calibration. I’d start without, to keep it easy, and only calibrate if you are unhappy with that.
Sorry. FTP test and all recent workouts done in a 52x13 I think. For the last interval of today’s workout I switched to something like a 36x18
That’s a pretty big change in flywheel speed for sure. Depending on the trainer, that will be very noticeable at the pedals. I believe the lower FW speed can lead to more sustained muscle loading over a greater portion of the pedal circle. This is shown a bit by the testing Shane Miller did a while ago. It parallels the feel I and others notice of a more demanding pedal stroke. Not everyone feels the same, and some quite the opposite.
Much probably comes down to variables like training history, muscle type distribution, rider weight and aero drag, typical riding surface coefficient of rolling resistance, typical surface grade and probably others.
In any case, we don’t have any conclusive testing showing if there is any real difference in training benefit. I suggest people experiment, try the full range of options and compare to their needs. Select and even mix gearing and cadence ranges to meet your preferences.
Yeah I agree, it keeps the chain line straight though!
Thanks Chad.
Wesley