Half Monty - Trainer numbers to Power meter numbers (indoor vs outdoor)


I just finished my Half Monty test and while doing so I decided to also record the “ride” on my head unit, which is paired with my Assioma DUO power meter pedals to see the difference in numbers (my trainer is a Tacx Flux 2).

So a few numbers:

  • Sufferfest Results: FPT: 239 W / MAP: 303 W / LTHR: 176BPM

  • Trainer Ramp Part power: Avg. 235, NP: 247, Max: 362

  • Assioma DUO Ramp Part power: Avg. 257, NP: 275, Max: 416

  • Trainer 20-minute effort power: Avg. 202, NP. 202

  • Assioma DUO 20-minute effort power: Avg. 222, NP. 222

  • Trainer Max. 1/3/5 minute powers: 320 / 302 / 285

  • Assioma DUO Max. 1/3/5 minute powers: 366 / 342 / 319

As you can see there is usually a ~ 9 to 10% difference in power numbers.

My question is, during the training plans when I decide to take my workouts outside, should I up the Sufferfest numbers by 8 - 10%?

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Aye. Things rarely match up - good call doing the parallel test.

It’s certainly a good guide fir zones when you’re riding that bike with that PM outside. I guess it’s be hard to follow a typical SUF workout with the constant power changes on a public road but having at least that knowledge will help follow the spirit of the workout.

The other thing is that outdoor power is different again as well (quite often) as the conditionsmare so different - so that’s the other reason it is more of a ‘guide’.

Unless you have the space (I guess someone’s people have massive off road areas maybe) to do the test outdoors too and then keep one set of numbers for the trainer and one for when they’re usable outdoors.

At least you know you’re own data.

And it can also help assess training stress as well (where people record that)