Tacx Flux wattage flooring issues in ERG mode

Anyone riding with a Tacx Flux experiencing issues with power flooring issues? - i.e. when I asked me to do 90 rpm which I was doing but was in the recovery it was just giving out far too much power. Do I just keep to the cadence figures or do I change gear, which kind of defeats the object of having an ERG enabled trainer?

I was using a borrower Elite Directo recently and it coped with the power in ERG really well but my Tacx just seems to not be able to cope with lower power targets.


What gear do you use when in ERG?

There are times when changing gear, particularly from big to small on the chainring, is necessary to alleviate power floor/ceiling issues. This is more a limitation of the trainer rather than “defeating the point”.

Sure, I understand that.

Although there are loads of trainers that just seem to work and I feel I have not made the best decision purchasing a Tacx but I am stuck with it now.

Thank you for your reply though.


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I’m using a 15 year old Tacx Flow wheel on trainer (made smart via some open source software). I run most of my workout on the small ring and centre sprocket but have to change down for recovery level work because of the trainer bottoming out.

Looking on the bright side, when I first started using SUF I had to change down 3 gears but after two months training and a 10% increase in power it’s now only 2 gears. It’s been a nice indicator of progress - perhaps at some point I’ll only have to drop one sprocket. Psychologically I actually quite like changing a gear or two as I switch from effort to recovery and vice versa.

Flux S user here.

Overall satisfied with my purchase, though I, too, need to shift gears on occasion to better match power with cadence. It’s certainly a step up from the Vortex I had been using.

Shifting is nothing that overly concerns/bothers me but is something I’ll be paying closer attention to in order to possibly justify purchase of a newer/better trainer. The other factor is if I continue to get power spikes like in the closing seconds of the final Hammer yesterday’s round of Nine Hammers.

I’d not noticed any tension shifts before/during/after the spike, but it certainly caught my eye, painfully squinted shut as they were.

I’m not riding a Tacx trainer, but I also have the issue with the power floor on my trainer. I’ll do one of three things when my trainer hits a power floor:

  • reduce cadence below target
  • shift into an easier gear
  • live with the power being higher than target.

The power floor usually happens in recoveries. I don’t stress too much if I’m recovering at the target of 100 W or a bit higher at 110 W.

For me, the big value of ERG mode is automatic control of power at target, and the resistance change required to handle the smaller power shifts that occur during an interval. I don’t mind so much having to shift gears for the big power changes between a short interval and the recovery.

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Coolio thanks for info.

Thanks for your reply, helpful.

I don’t mind changing gears obviously apart from the fact that other trainers I used recently you just ride in ERG no changing gears at all and it just works.

Unfortunately Garmin have taken over Tacx but they are not really keen to help out when there us an issue.

I will just plug on with it.


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Cool I will just live with it or change gear slightly I had a practice today with it again and I kind of know what I am doing now.

I will keep to cadence and sack off worrying about high power if it’s the recovery portions.


Nailed it.

I’ve used Tacx product for 20-ish years now and only have recently begun to notice minor “issues.” Wait & see, I suppose.

I have the same issue but also stuck as it was an investment

I’ve had the original Tacx Flux for 5 years and it’s never skipped a beat. I typically ride it in Erg mode in my granny gear and rarely have to change gears. My bike has a compact up front and an 11-28 rear and 172mm cranks.

It can handle a power as low as 50 watts with a cadence of 90rpm with the bike in it’s easiest gear. For sprints or for low cadence (50-60rpm) high power grinds like in GOAT, I have to change up the gears. Usually just 2 or 3 on the cassette, sometimes I’ll flick onto the large chain ring.

If I’m riding something like GOAT, I just stick the bike in a higher gear for the whole thing.

Cool thanks for info