Are all Smart trainers the same?

trainer

#1

Hi all

Just about to hit week 5 of SSB when my Tacx Flux decided to blow up, fear not, the store swapped it right out

However, today I went to do a vo2 session and first session on new unit and absolutely died! I had to turn down intensity to 90% and still struggled. Previous Vo2 session I ramped up to 110% and smashed it.

I didn’t want to do a ramp test as I’m only a week away from doing a new one and also didn’t want to mess up my SSB. But could my new turbo be different to my old one in terms of power reading? Or do I just put it down to a bad day on the bike


#2

Assume they swapped it for another Flux? As long as it was calibrated then should read the same as your previous Flux.

If it’s a different trainer, you’ll need to test again.


#3

I think every trainer is different, even the same brand and version with the same calibration… easiest would be to retest…


#4

I’ll see how it goes on some sweetspot type stuff and give it a whirl


#5

Kinda, but not entirely true. Keep in mind the accuracy tolerance stated with every power measuring device. The Flux is something like +/- 3%. If you had one trainer at the top end of the tolerance, and compared to one at the bottom of the tolerance, that is a 6% delta between the two.

Add to that the fact that it seems common for some trainers to exceed those stated tolerance ranges. So the picture of actual variation from one unit to the next may well be larger than that.

The only way to know with any level of certainty is to use a 3rd power meter, that is applied during use of each trainer, and see what the deltas are to that shared measurement tool (noting that the 3rd PM could also be wrong, but hopefully consistent enough to trust enough for comparing to 2 other trainers and their respective data).

All that is to say, it’s not a bad idea to do a Ramp test again to establish or confirm your FTP. The same rule applies, if you change power measurement (even replacing an apparently identical item), it is a good idea to re-test.


#6

Didn’t think about it as deeply!!:blush:

And you’re right!!

Also bear in mind, they say that the accuracy of the Flux improves after it’s warmed up at about 10 mins, worth warming it up an recalibrating before starting a session😊


#7

Common oversight. People ignore the manufacturing tolerances when they really shouldn’t. Sadly, we aren’t to a point where we can say that all power measurement is equal. Too many of these devices have manufacturing issues as well as user setup and calibration issues.

It leaves the opening for wide variation in power reporting. That was all pretty much OK when we were just using them for personal training as a yardstick to set and track our own progress. But as we now use these tools for direct competition (or mix between power measurement devices within our own stable), the variations become more notable and possible consequential.

It may be another 5 or more years before we get to a point where we really want to be with respect to having easily reliable and mostly accurate power without too much hassle or expense.