TSS and kJ on a MTB

I recently started riding MTB and have a power meter on my bike. Compared to road, I noticed that technical descents can feel tough but it is not reflected in power, TSS, or kJ.

Is this something you experience folk already know and account for somehow? Or is it thought to be negligible?

On a technical descent, its definitely not negligible. Here’s a MTB race I did where you can see my HR during the descent was not a whole lot lower than on the climb.

There’s no great way to do this. You could just ignore. You could go off HR TSS, or you could manually adjust TSS based on RPE for how much descending you did.

I don’t have a PM on my MTB, so I gauge TSS based on RPE.

The main thing is to be consistent with whatever approach you choose.

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Thanks for the analysis! I just looked at a ride I did yesterday and see a similar pattern. It would be nice to be able to combine hrTSS and power based TSS.

It kind of is already accounted for in the intensity factor isn’t it? I 100% agree that technical descents are significantly more grueling than road/gravel descents. It’s like having to perform 2-20min sets of split squats at the top of each climb, but it’s not a Training Stimulus in the same way as power generation.

Are you looking at it to gauge/measure fatigue from a ride? Or in terms of fitness gain/training stress?

Both, to quantify fatigue and also fitness. I am thinking about it within the context of my training. I’d like to stay close to my weekly TSS targets. Also, I look at kJ as a guide for fueling.

Yeah, I understand. I find it hard to quantify MTB stress in terms of TSS and equating training stimulus week to week. In terms of fatigue, I find that I can relate the IF to the amount of fatigue I’ll have after a MTB ride.

I don’t worry about it as I don’t believe there’s a lot in it. Not everything needs a TSS number assigned to it.

Plan on a bit more fueling and recovery for hard mtb days, not sure how to quantify that beyond feel and listening to your body. Maybe shoot for a slightly lower weekly TSS over-all if you’re concerned about your MTB rides taking you into the red especially if you’re new to trail riding. I also use a PM on the MTB and I do weigh those rides a little higher in terms of time needed to recover. When I see a high TSS on a MTB ride I just know that I typically respond best with an extra recovery day/ride the following week.

thanks all! I don’t think it’s a HUGE deal- I was mostly wondering if there was a consensus on how to treat. I am taking your suggestions though on TSS and more fueling.

“All TSS is not created equal”