How to properly estimate TSS

I am using virtual power and it doesn’t connect to anything other than TR. When riding outside, my Garmin tracks my ride, and then loads to Strava, which can load to TR. TR then asks me if the workout was easy or hard on a scale from 1-10, and estimates the TSS. My question is, what level of difficulty are you supposed to put? If it was a 3 hour ride with 3,000 ft of climbing (not uncommon for us at all around here), some parts like uphills and grinding on the flats to keep up are hard, but then the downhills are easy and drafting is easy. If I put “hard”, then it assumes the entire 3 hours were hard. Any suggestions on estimating this?

Think of the rating scale as relative to your maximum potential.

A 10 would be as hard as you could possibly go for three hours. Some sections may be harder, while others are recovery, but overall you could not have gone any faster, and your tank was empty at the end.

A 1 would be the pace that barely raises your heart rate for the entire time.

It can sometimes be tough to rank, but just give your best estimate based on how tired/fatigued you are at the end, and how much energy you have left in the tank :+1:.


Thanks. I’ve kind of been taking an “average”.

Take a look at the Elevate Plugin for Strava. I think it generates a hrTSS estimate if power-based data is not available.

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This article explains it pretty well:

Estimate TSS

For me I use average HR for the ride in the numerator and my FTP HR in the denominator. I’ve modeled that in excel vs calculated TSS in Cheetah, Sttava, TR and WKO and it’s every bit as accurate.


Awesome! Thanks guys!

I use HR to estimate