TSS How to calculate a 5 hour mtb race?

How do you guys and gals choose estimated TSS on rides without a power meter?

I did a 50 mile mountain bike race without a power meter a few months ago. It took over 5 hours. It was my only race/ride like this of the season so I have no other reference point for pace and intensity. It was brutal. My body was not accustomed to this type of torture. 40 miles of unrelenting rock gardens with 10 miles of fire road.
I want to add approximated TSS to that ride in TR. It was a race, so logic suggests I choose “Race Pace” in the TSS dropdown. However, my race pace was probably more like ‘Tempo’ in terms of power output, ftp and zones. But it was ‘Hard’ as all hell. In fact, it was ‘Very Hard’.

Race Pace - does this only apply to a certain style of racing? Specifically, 1-2 hour races.
Hard - it was extremely hard. Totally gassed at the end. Had nothing left.
Tempo - seems to apply more to a quantifiable power and ftp in relation to Zones - sweetspot, endurance, VO2, active recovery, anaerobic, where ‘hard’ and ‘race pace’ refer to Intensity.

Strava’s ‘Training Load’ is very close to TR’s TSS. For example.
Augusta on TR - TSS 120

Augusta on Strava - Training Load 118

Unfortunately, the ‘Training Load’ and ‘Intensity’ variables are not available on this ride in Strava for some reason. Maybe a newer feature or maybe it only pops up on TR rides in Strava. My average heart rate for the race was 159 which is the heart rate I currently have during a sweetspot interval on TR, which seems insane to sustain that for 5+ hours. But the course was a full body massacre and not just turning the pedals over. On the trainer a HR of 159 allows my legs to put out around 300w but on a brutal mountain bike ride that only allows my legs to put out around 150w average (estimated by strava). Mountain biking is a full body workout on top of the fear of dying.
I could take a 1 hour TR ride that has the same average heart rate and multiply it by 5 to get a TSS, in which case it would give me around an estimated TSS of around 550+/-. Might be possible. It probably sounds like I’m obsessed with this but it’s really not that big of deal. Just trying to lay out all the variables and don’t want to be massively over or under on my estimate and to gain a better idea for the future.

Just found this from Training Peaks
TSS = (sec x NP® x IF®)/(FTP x 3600) x 100

  • “sec” is duration of the workout in seconds,
  • “NP” is Normalized Power® (don’t worry about this for now),
  • “IF” is Intensity Factor® (a percentage of your FTP; in other words how intense the effort was),
  • “FTP” is Functional Threshold Power (your best average power for a one-hour race or test),
  • and “3600” is the number of seconds in an hour.

(19800 x 126 (suggested by strava) x .7 (guess by me)) / (295 x 3600) x 100
= TSS 164 hahaha no way but maybe I screwed up the calculation.

I go by how sore I was the day after.

  • I could easily ride the next day with minimal soreness: Under 200 TSS
  • I had some soreness but could manage a decent ride if I needed to: 200-250 TSS
  • Coffee ride only: 250-300 TSS
  • I don’t want to look at a bike: More than 300 TSS
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hahaha makes sense to me. Can we add that to the TSS drop down on TR?

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I know there are instances where you can go over 100 TSS/hour but over 5 hours ?? Is this doable ? Looking over my own paltry stats I did 108 in 64 minutes and was cooked.

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Ha. You’re right. I think that’s where duration vs. intensity comes in as well as mountain bike vs. trainer ride. I had some weird muscles sore after this one. Arms and back where on the trainer it is only legs. But yeah. No way 100 TSS per hour for 5 hours.

I did a similar ride (not a race though) with my brother. 55.5 miles, all singletrack at an agressive pace which took me 4:55:10. Was smoked after it and lost 8 pounds :flushed:. No power meter but my TSS estimation was 338. Seems a little high. I have a Traditional Base 2 workout scheduled tomorrow lasting 2:45 mins in zone 2 and zone 3 (Martin Hill). TSS for that workout is 146. I know I couldn’t double that effort and even if I could that only gives me 292 (assuming TSS is a flat calculation and doesn’t compound over time).

All that being said I think TSS estimate is the pace/zone, not necessarily RPE. Though I have absolutely nothing to back that opinion up.

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That makes sense. Especially considering the duration of that workout.

RPE is too subjective, has so much to do with fear and outside factors, could cause you to over or under perform. Should have nothing to do with TSS. Agreed.

If it was all out, I’d put in race pace. TR automatically adjusts the IF to be appropriate given the duration of the race - so a 5 hr race will use a lower IF than a 1 hour race in calculating TSS.

Last summer I did a 6 hr MTB race averaging my threshold heart rate for the duration. Was completely wiped at the end.