Can y’all help me understand why there’s such a difference in AP results between all the different tracking tools I use (maybe I should just not use all 4, but that’s a separate problem)? I get that all use different algo’s for the “net power” but shouldn’t AP be the same / close? Strangely, sometimes Strava is higher than Garmin, but mostly it’s lower
From a 50min crit last night, here’s what all 4 of those showed …
Yup, Normalized Power is going to be different, because that concept is licensed so the formulas and different. For Average Power, that does not make sense they could be lower. I could see Strava being higher, if it automatically excludes stops. But being 12W lower (and 20W lower in Xert) is a mystery.
I’m pretty sure all my averages (between Garmin, Strava, and TrainerRoad) all match exactly or are within 1 watt.
Just verifying, usually power on my Garmin appears 10w lower on Strava. For trainer rides (zwift/rouvy) Strava Matches up - I also record these indoor rides on garmin, also matching up. So I am guessing Strava’ is doing something different
Yup, Normalized Power is going to be different, because that concept is licensed so the formulas and different. For Average Power, that does not make sense they could be lower. I could see Strava being higher, if it automatically excludes stops. But being 12W lower (and 20W lower in Xert) is a mystery.
I’m pretty sure all my averages (between Garmin, Strava, and TrainerRoad) all match exactly or are within 1 watt.
I’d be curious if you checked, and could validate all are the same. I find that all 4 of them are NEVER the same
On a normal training ride the figures are usually close, but when we race (particularly crits), the figures are consistently wildly different
Is your Garmin set to include zero values for power?
My garmin 840 is set to:
**Cadence Averaging **- do not include Zeros
**Power Averaging - **include Zeros
Is this right?
Whether it is right or not is up to you and how you use the data.
If you were not including zero power that could be a potential source of the difference. Wonder if the exclusion of zero cadence but not zero power is throwing things off - might be worth doing a ride including zero cadence to see if that changes anything?
Yup, Normalized Power is going to be different, because that concept is licensed so the formulas and different. For Average Power, that does not make sense they could be lower. I could see Strava being higher, if it automatically excludes stops. But being 12W lower (and 20W lower in Xert) is a mystery.
I’m pretty sure all my averages (between Garmin, Strava, and TrainerRoad) all match exactly or are within 1 watt.
NP is trademarked; the formulas aren’t patented.
Is your Garmin set to include zero values for power?
My garmin 840 is set to:
**Cadence Averaging **- do not include Zeros
**Power Averaging - **include Zeros
Is this right?
I’d add ensuring auto-pause is also off on the device. Strava generally has weird averaging for me, and diverges the more % of time I’m not moving during a ride (even though I have auto-pause off).
NP is trademarked; the formulas aren’t patented.Garmin and TrainerRoad both use Normalized Power. So I would expect their formulas and results to match. Strava and Xert use their own concoctions: “Weighted Average Power” and “Xert Equivalent Power.” So, I would not expect those two to match each other or Normalized Power.
Just as another data point, I ride with a girl here who has Strava showing about 10W lower than on average on every ride. Garmin and TP match up. It’s been going on for a few years and she rides every day.
ok strava is stupid. Just saw guy I follow finish p1-3 race. Strava shows 278 weighted average power for the 74 minute ride. But it said his best 1 hour power was 264w…
That’s normal/right. 1 hour power is pure average of all the overs and unders. But the ‘weighted power’ as the name implies and is the same as NP (but slight edits to the formula) it biases to the overs more than the unders.
The theory being that if you do a steady state ride at 200w, but then for 1minute you do an all out sprint at 700w, that’s going to be more fatiguing than the true average of 208w.