Tx @bobmcstuff . Intervals.icu TSS excludes coffee stops because it doesn’t make sense to me that your TSS will be higher for a ride if you add 30 mins in the middle having coffee. So that would be one reason why it is lower sometimes. Apparently this is the burrito break discussion on wattage (before my time). It always uses your manually set FTP.
With regards to HR TSS in Intervals.icu you can choose between 3 models:
- Time in zones: Regression model based on time in zones for your previous rides with power and HR. Works well if you have those and your HR and power zones are aligned. Sometimes overestimates low intensity activities if you don’t have a lot of Z1 riding with power
- Average HR: Simple model that looks at previous rides with power and HR and works out TSS/hour for a given average HR.
- HRSS (normalised TRIMP): This uses your resting, threshold and max HR and apparently is what Elevate uses. It’s nice because you don’t need any power data. For me time in zones produces better results but I have loads of power and HR data and my zones are aligned.
Intervals.icu will also estimate TSS using pace data for running and swimming.
You can also always choose to enter whatever load you like. The dialog shows the estimates from power, HR and/or pace as a guide.