Get My Head Around TSS, IF, NP etc

Hoping someone can point me in the direction of some learning materials or provide a concise and easy to understand explanation so I can get my head around it all, I’ve recently got a powermeter and some outside rides are confusing me…

For example, my ride from yesterday, didn’t feel like it was particularly hard work, average HR of 136 (max is about 160), average power of 210 (77.7% of FTP) for an IF of 0.91 and TSS of 101 (NP of 247) over 1:12.

Having just finished SSBLV2 this IF of 0.91 is in line with the hardest workouts in the plan and they taxed me an awful lot more than this medium outside ride did…

So what I’m asking is:

  • why does the outside TSS seem to be given more easily than inside?
  • is there something I’m not really considering when thinking about perceived effort, IF, NP and TSS data and how they fit together?
  • is there any good reading material I should take a look at?

Thanks all

Sounds like discrepancy between inside/outside ftp based on different power meters etc…

What are you indoor and outdoor setups ?

Both inside and outside on the same bike with the same Favero assioma pedals giving the power readings.

Sure, same tools, but there are many other variables here.

https://thesufferfest.com/blogs/training-resources/understanding-the-difference-between-indoor-and-outdoor-power-numbers

What trainer do you use, and gearing used?

Also, depending on the make-up of your efforts you can create the same IF but with very different fatigue levels. You can go out and just ride at a consistent 91% for the whole ride or you can ride east and every couple minutes do a 20 or 30 second sprint at ~200% FTP. You would probably feel more fatigued after the 91% ride but would have the same IF at the end.

Just a dumb trainer (a Minoura LR540) but I did notice that my cadence on the trainer is higher on average (low 90’s) than outside where I have to think a lot more about keeping my cadence higher (would naturally fall in the low 80’s).

Maybe this has something to do with it. The outdoor ride is much more spikey with stop/starts, coasting, powering up etc compared to the indoor trainer rides where I’m better at holding the required power targets closely…

This is the main reason, those start/stop creates some NP busters by going hard for a short time and then riding “easy” for the rest.

Also consider that the TR workouts are made to tax ONE system at a time (mostly) and really drill it.
When you’re outside you’ll most likely tax almost all, if not all, systems, from coasting and zone 1 to some sweet spot, some VO2 up longer climbs and some anaerobic for the short climbs and start/stop.

If you want to compare. Do a workout outside and you’ll see it doesn’t get easier.