Tacx Flux and Direto X power curves

Context: I work all week in Surrey and use Tacx Flux however at weekends I am home in Suffolk and use a Direto X. I always use the Tacx for ramp tests in order to remain consistent and run a weekly calibration via TR.

Problem: The RPE on the Tacx is substantially greater than on the Direto. Previously I put this down to being at work all day and training in the evening however I managed to get a few rides in around midday due to the lockdown and confirm the Tacx requires circa 5% greater effort (HR based) than the Direto. I plan to fit my DZero cranks to both (once over the lockdown) and confirm the difference but wondered if anyone else has the same problem or able to suggest a way to get greater parity for the turbos?

By coincidence, I did my first ever zwift race (TTT) this week on my flux.

It was a thoroughly miserable experience and I simply couldn’t hold target watts. This was after a week recently where I set a 20min PB so form was good.

I couldn’t shake the feeling that the RPE for the effort felt out of whack so I decided to check the output of my Flux against my Powere meters on two other bikes (my dedicated trainer bike doesn’t have PM). At 300w it was over 30w lower than both rotor PM’s!!!

Calibrated all the devices multiple times and the difference remained.

Always felt that trainerroad sessions felt a bit hard compared to wattbike and outdoors. Now I know why…

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Thanks Nicco. That concurs with my anecdotal evidence as one of my pals told me his FTP yesterday afternoon and i was gobsmacked. I’ve ridden with him and he is fairly handy so i was surprised it was so much lower than i anticipated. I asked what his trainer was… Flux!

I have a flux and believe they read low. At least a good 10% lower than my stages power meter. I have TR take my power reading from the stages so it’s consistent both for indoor and outdoor training and find this works well. The RPE is similar for my indoor and outdoor rides then.
So if you have an on bike power meter, take your reading from that, otherwise I would say from all accounts here, the Flux reads low and you need to compensate for this.

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I’m a bit narked to be honest. Firstly that the trainer is that inaccurate as an decently expensive bit of kit. Second, that I didn’t properly investigate it before now.

I always do my FTP tests on a wattbike and that has been pretty close to my best efforts on the road. The only problem is I’ve been using the same FTP for TrainerRoad…

I’ve told friends in the past that I find the TR plans incredibly tough. Well now I know why!!

In the experience of this board (I’ll consult DC Rainmaker as well of course) what is the most accurate turbo trainer? Neo or Kickr? Or something else?

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