Gearing in Racing

I’m sure this has been covered, but I can’t seem to find it, so apologies in advance.
When it comes to racing on zwift, whats the deal with gearing. I find I’m in the small ring 95% of the time, pushing power that on the road I’d be in 53x15 or so. Yet in a zwift race, for the same power its a 39x??..even on “flat sections” the 53 seems almost impossible to turn for a sustained period. This doesn’t happen on the road.
What am I doing wrong?

I haven’t had anything like that before.

Are you saying it only happens in racing?

Tell everyone what trainer you use, what device you run zwift on and how you connect the two.

Hi Ben,

Its a tacx flux trainer. I usually pair the trainer to zwift for the resistance etc and use my own power meter for reading power and using my iPad.

Hmmm I haven’t seen anyone report a similar problem. The common advice is worth stating here though

make sure you update to the latest firmware for the tacx
Make sure you complete a spindown calibration on the tacx or zwift app
Make sure your FTP is accurate enough (not 0 or 100 or some default) apparently it makes a difference.