Got a question for you guys. Today I did a ride indoors on my JetBlack Victory trainer (auto calibration). I did Cardinal workout and for the three intervals I was able to hold 240 x 10 minutes in ERG mode. During these intervals my HR was somewhere between 146-150 with an average of 148. The ride was moderate to hard at times. Now for my questions. If I was to go outside there is no way I would be able to hold 240 for 10 minutes and if I could my HR would be in the 160 range. Why does differ so much between indoor and outdoor. From everything I read indoor is supposed to more difficult but for me it seems the opposite for me. Anyone have any thoughts here.
Are you using the same power source indoors and out?
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No but they are both calibrated. The one is from the JetBlack Victory is auto calibrated and the one on the bike is a 4iiii PM which calibrated every couple of days. Maybe I will go outside tomorrow and give a try and report back. Another example last week I was climbing a hill near my house on my gravel bike which also have a 4iiii PM. Its fairly long about 2km at 7.1%, 147HR and 220W. So you can see its 20 watts lower then what I can do indoors at the same HR.
Ride with both recording on the trainer. I would bet they are not the same.
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I have an old Kickr that reads 20 watts low no matter what. I can calibrate it and do a factory spin-down and it makes no difference.
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This is definitely not the case. It is so much easier to push my hr up and hit higher power numbers outside than in.
Inside feels like slowly dying. Outside feels like rapidly escaping. 
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At least in my experience⌠Riding indoors is like riding on the flat with no wind (or a constant low gradient if you set resistance high enough). Everything is controlled and riding with consistent power is easier, but it doesnât resemble what you get in real life. Outside you are going to get wind gusts, change in terrain, change in surface, etc. You are going to get micro rest and micro bursts. You are also going to get the benefit of drafting, chasing, and just general excitement of the change in scenery.
Outdoors I struggle to keep up average power because we have so many hills here, so indoor itâs much easier to hold a consistent power for a timed interval on the trainer. That said, itâs much easier for me to hold high power for the duration of an interval outside.
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I wouldnât say its âeasierâ indoors but I can generally more consistently meet power targets over a longer duration indoors (circa 2-55min power records this year are all indoors), maybe because the environment is more consistent and I donât have to worry about externalities, but I can deliver more short term power (sub 2mins) outdoors easier. Having said that Iâve not done any TTâs this season; looking at last season the majority of my power records were outdoors.
Not sure if this âauto calibrationâ is the same as in a wahoo kickr. I read somewhere that if you mainly do workouts in ERG mode you might have to do a âmanual spindownâ anyways. This was the case for me on my kickr atleast that should also have auto calibration.
Just a data point but my JetBlack Victory reads around 10-15W higher than every other power meter I own (1 Favero Assioma, 2 Sigeyi, 1 Magene). So itâs an instant 10-15W boost indoors. I was wondering why workouts felt easier so I tested it against a few bikes. Yours might be similar. Just a thought.
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Calibrating a power meter is sort of resetting itself. Like hitting tare on a scale. It doesnât mean the power results will be accurate with other power meters. As already mentioned, you need to ride the 4iiii on the JetBlack and do some comparisons.
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And it doesnât necessarily mean either are âwrongâ. Theyâre measuring in different places, left side only v total power, stated accuracies etc.
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I will have to do a comparison against my road bike and see. Maybe that is what it is.
I find i can do much better numbers indoors for sure. I can just âlock inâ with a long hard climb with banging tunes on the headphones, a blast of cold air and Erg mode. Outside i feel less impressive. Maybe itâs my lack of long climbs locally as the flat is always harder to push out power numbers. Itâs certainly not a calibration issue though as i have excluded that.
Calibration is wildly misused with these devices. All theyâre ever doing is zeroing the reading against a known 0 input, applying a simple offset.
Calibrating can only ever be done in a factory/lab under controlled conditions with a known input power system - itâs done at best once in a PMs lifetime.
Being âcalibratedâ several times a week is meaningless, obviously the Jetblack is reading way higher than the 4iiii, no clue which one is right unless you can get / borrow a pedal based PM to compare them both to.
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Hey @BigK75 
Sounds like you have about 3 different power sources? One from your JetBlack Victory and 2 from your 4iiii PM.
As everyone has mentioned, itâs natural to have every power meter read differently, even if theyâve been calibrated. As well as noticing differences in power output, especially when youâre comparing a smart trainerâs ERG mode to outdoor efforts with shifting terrain and gearing.
You mentioned you went out on your gravel bike and went up a climb. Was this on the dirt or the road? This can also have an impact on power output, as could weather, or even having a proper warm-up
We recommend, if possible, to use one power source for indoors and outdoors so that there is no difference in power readings. You can do this with Power Match.
Lastly, I also wanted to mention that HR varies a lot by external factors. Hereâs a quick read on it: Power vs. Heart Rate
I find them to be physiological basically the same, but outside mentally way easier.
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Yes it was a dirt road and I was was warmed up. I cannot use Power Match because I use Zwift Ride at home but I will do a check to see how the power meters compare.
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Let us know how it goes!