Not all TSS is the Same.....They Say!?1?!

So yesterday I sustitued an outdoor group ride (60 degrees in Jan in StL is mandatory go outside weather) and my TSS was 243

If you look at the link I rode to the ride, (chatted (damn I love my crew here), rode the route (ave power 218) then chatted more after and rode home. Ave power 158 for while out from start to finish

Skip ahead to today (I was dreading this workout as the temps were still warm but cloudy) to Glassy and a 1 hour 20 minute workout. My ave power was 158 and my TSS was 81 This hurt way more than hanging with my friends yesterday

What gives? Isn’t it hard to do the prescribed TSS and sneak in some fun cycling every once in a while? Why are they so off?

My week and how weird that outdoor ride looks!

Same power measurement device on indoor and outdoor rides?

EDIT: misread the initial question oops. Never mind! :slight_smile:

Hey Thomas!

For you to have a NP greater than your FTP on an easy 2 hour ride, there is likely something going on with your power meter. TSS is based upon NP, which weights your hard efforts greater than your easy ones. It looks like your power profile is a little “all over the place”, and since the hard efforts are weighted more highly, this is throwing off your NP and also your TSS.

Were you having periods of sprinting or surging, or was this a fairly sustained effort? If it was a very sustained effort, then you are having pretty severe power spikes that will need to be addressed.

It looks like you were using a smart trainer as your power source for your indoor ride, and the power readings look much less volatile. This could suggest that your outdoor power meter could be the source of the issue here.

I would recommend reaching out to our Support Team at for further investigation into your power sources. They should be able to run you through a short workout with both your trainer and your power meter paired to:

  1. Determine if there is a significant offset between the two readings
  2. Determine if the power meter volatility is abnormal.

Best of luck and don’t hesitate to reach out if you have any further questions :slight_smile:

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Outdoors i have a stages, Indoors i just use a Hammer (smart). They match close (relatively) but I am goofy about about straight lines on TR so I don’t use Power Match (sorry TR team) :thinking::sweat_smile:

What is odd to me is an hour and twenty minutes of pedaling at a cadence of 100 (ave) and wanting to through the towel in only gets me 82 TSS and a fun outdoor/and a bit quick at times gets be 243 in TSS

TR suffering needs a higher TSS

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@Bryce has provided a very helpful answer.
However I would be looking at the outside ride as being out of sync.
The numbers don’t seem to add up to me. Sub 3 hour ride, ave power 158. I am thinking 60 TSS an hour maybe

What is more out of sync is the ride the week before. 203 for a sub 2 hour ride. I doubt it unless it was very all and if so then I suspect your FTP has been input incorrectly somewhere. Have you checked your Garmin/Bolt?


Yup - workout like this are usually about 80-100TSS for me… An hour and a half of Over/Unders bags me about 105TSS.

I agree that the TSS of the outdoor ride is the suspicious number, not the indoor ride.


Is your FTP set the same ? Also be aware that your outside FTP could be higher than your inside FTP due to cooling etc. The formula for TSS (sec x NP® x IF®)/(FTP x 3600) x 100

This is a good shout. Looking at @Thomas_Frisella ride it says you were anaerobic for 28% or 37 minutes. That doesn’t sound like a gentle spin to me if correct.

Looking at the rides, your average heart rate is pretty similar (around 150 for the workout and 151 for the laps). But the NP is totally different.

Either your Hammer is under-reading, or your Stages is over-reading, or both.

Looks to me to be a problem with the Stages outdoor ride. Maybe calibration. The constant spiking to double your FTP would take a huge toll on your body if that was correct. Also the peak wattage of >800 watts is odd at over 4 times your FTP. I can barely hit three times FTP in an all out sprint.

Others have pointed this out - but there are only a couple of possibilities here

  1. The device that tracks your power indoors that you have used to set your FTP in TrainerRoad is dramatically different from the device upon which you did this ride. Both devices could be consistent to themselves, but wildly different
  2. The outdoor PM is broken

There are multiple 10-15 minute stretches in your outdoor ride where you are well over a rate of 100/TSS an hour. This highly unlikely and really only possible if you have an ‘incorrect’ FTP setting or a busted PM.

So either your stages is reading dramatically higher than your Hammer or the stages is broken/miscalibrated.

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Tuesday evening will be the test.

I typically do my TR then go on a night ride with a group, I will be calibrating the Stages prior to heading out and see if that reins in the TSS to a normal level.

This will really only give you another data point but not a great comparison. If you really want to test I’d recommend you do your next indoor ride with one device capturing the data from the trainer and a separate device capturing the data from the power meter. This will give you as close to an apples to apples comparison between the two measures and should quickly point out the differences.

Would, of course, recommend a calibration of both units after an appropriate warm-up period.

What you’re describing will only give you more Stages data with nothing to compare it against

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Good call, I’ll run the Stages to my Garmin and Smart Trainer to TR and do a little comparison.


You can also export the .fit files to the dcrainmaker analyser if you feel really geeky, but there’s a five dollar charge to use it

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Check you’re including zeroes in whatever device is recording outdoor power. If not, all that time resting and coasting could not be counted which would throw you average and TSS way off.