New smart trainer power differences Hammer

I recently treated myself to a new smart trainer a cycleops 2018 hammer I really like the feel of it, its much quieter and smoother and the resistance changes are great.
makes Zwift a lot more realistic and enjoyable.
(what I used to use which was a elite Muin just a dumb one paired with a power meter)
anyway Ive done a couple Zwift races on it and it seemed to read a lot lower power than my Garmin vectors and Shimano 9100P.
after the first race I made sure everything was up to date…

  • hammer software,
  • Garmin vectors firmware
  • Shimano power meter firmware
  • calibrated the trainer using the rouvy app
    even chucked a brand new dura-ace chain on (as I read that you can loose a bit through old chain, it was due a change anyway)
    the trainer came with a brand new Ultegra cassette.

so the second race I dual recorded with the vectors running in the background as well as the Shimano.

the power averages was like this for the 1hr long race

cycleops hammer: avg power : 261.8watts
Normalised Power: 330.4watts
Max watts: 1105watts

Garmin Vector: avg power: 310.4watts
max watts:1191watts

Shimano 9100P: avg power: 306.4watts
normalised power:373.7watts
Max power: 1144watts

as you can see the hammer is around 15% lower than the vectors, I feel like I’m missing something I have read other places the smart trainers can read lower than power meters but it seems quite a lot.

I have a SRM sitting on another bike which I might have a look at the difference tomorrow but the SRM always felt very similar to the Shimano 9100P its not going to be 50watts different.

has anyone else had anything similar with a Hammer or any other trainer.

thanks for any input! :slightly_smiling_face:

That’s a big difference. You can pair your power meter to zwift and your hammer as the controllable.

I have a H3 and somilar to my 4iiii left crank over a hour ride. I cannot remember the loss you will see from pedals to a trainer but I think 10% is about normal. They never will match.

With that though try to calibrate hammer with the Saris app and see if there are any firmware updates. Worst case if you trust the garmins more then use that as the power source and the hammer as the controllable for the elevation part.

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