Wattage capping out way too early in sprints

Hi, I have a pretty basic setup with a TACX Blue Motion dumb trainer, Garmin cadence, speed and HR monitors feeding into a Macbook pro via an ant+ dongle, but perhaps crucially, NO POWER METER, so am dependent on the Zwift algos for best guess on my wattage. However I am reasonably confident that it’s in the right ball park having compared it to wattbike workouts done in the past. For most rides this setup works fine.

But when I try and drop the hammer and go flat out the watts peak at about 380 (my FTP is 335) and then drop off to about 350 as I go harder. I can’t seem to register a reading greater than about 380 watts. My hunch is that the ant+ feed gets overloaded the harder I go and without a power meter I will just have to suck it up, but any suggestions would be greatly appreciated.

Hi, Adam! Welcome to the forum.

I believe the TACX Blue Motion is a supported trainer (https://support.zwift.com/en_us/wheel-on-trainers-r1B5nQWxS#Tacx), so the virtual power cap should be 1200W I think.

Have you selected to correct trainer from the list in Zwift? If not, you might be using the “unsupported trainer” profile. That is capped at 400W so would tally with your problem.

See this from ZwiftInsider:

Also check these troubleshooting tips:


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Have a similar setup with the same issue. 380W seems to be the limit.
I think its down to zwift setting the resistance relatively low as has been metioned in other posts.

Tacx blue matic setting 3 needs increasing

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