Computrainer Calibration workaround

There’s a small workaround to Calibrate the Computrainer while still in game (not having to quit after 10 mins of warmup).

  1. Ride in Zwift as normal with your Computrainer for about 10 minutes.
  2. Disconnect the PC Ext from the Computrainer head unit, The calibration mode should popup, if that doesn’t happen, simply disconnect the power Cable coming from the Resistance unit to your Computrainer head unit and plug it back, the Calibration mode should start.
  3. Calibrate as normal and save it (F3)
  4. Connect back the PC Ext cable.
  5. This is the tricky part, it’s seems as Zwift now won’t recognize your Computrainer when searching for a Powermeter/Cadence, plug out the USB Adapter from your PC, wait about 5s and plug it back in.
  6. You will now have the ability to choose Computrainer as the Powermeter again, this time, Calibrated.

Interesting. I just did the pre-ride warmup outside of zwift.

I also just do 5-10 minute warmup before switching on Zwift. I also check it after I stop my ride to check it was indeed at the correct calibration.

I used to warmup outside of Zwift, or warmup inside of Zwift and then discard the ride as well.
I now take a first lap slowly and then stop to calibrate this way.
I hope there will be a feature that will be able to communicate with the head unit so calibration will be seamless (like in other apps), it will also be cool if we could control Zwift from the head unit as well.

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Perfpro do that and it does work pretty well.
I quite like the Velodrome idea that some have put forward where you can warmup and also calibrate if needed then choose when to enter the course.

Agreed that perfpro handles this really well and that it is a good model to follow. If Zwift does support this it would be nice to have the program hold your place among other riders (or simulate you holding the same power while disconnected) so that there isn’t a disincentive to calibration.

In the above steps I suspect (and I’ll try to see myself later) that you could substitute steps #5 and #6 by pressing “a” and reconnecting to the CT as a power meter source.

Doesn’t step #2 have the strong potential to blow the Computrainer fuse?

Step #5 - so you have to hop off the bike, unplug USB, wait, plug it in? Just want to make sure I am understanding this part. If so, in my situation I would need a 6 foot USB extender so I could have to right next to me while remaining on the bike. Otherwise it is a crawl to get to the back on the PC to unplug stuff.

It is inly the small 1.5mm jack on the handlebar unit that you would unplug.

I get to step 6.  Zwift finds computrainer and then promplty drops it after a few seconds.  Unplug USB, plug back in - same issue.  It would be nice if you guys found a way to fix it, not that it’s a paid product (out of beta).

The default calibration setting for the Computrainer is 2.00.  Instead of setting the head unit to read the current wheel resistance, I’ve gone through the process of adjusting the resistance so that it calibrates to 2.00.  Before each ride, I inflate my tire to 100 psi.  As the tire and resistance unit warm up, it comes into calibration at about 2.00.  I check it about once a week, usually before a big workout or group ride.  After a full warm up of 15-20 min, my calibration reading ranges from 1.98-2.04.  Pretty close and saves time and hassle on most days.  

I don’t understand the “adjusting the resistance so that it calibrates to 2.00”.  Are you saying that you leave the pinch roller engaged all the time and just turn the power to the unit off?

Sorry for the confusion.  While the computrainer is in calibration mode and disconnected from Zwift, This is my procedure.

  1. Inflate tire to 100 psi

  2. Manually set the wheel tension using computrainer tension knob

  3. Ride at 150 watts for 15-20 min per the Racermate protocol.

  4. Instead of using the pressing F3 to set the calibration, I adjust the tension knob so that my calibration coast down is 2.0.  This may require a few coast downs adjusting the tension knob up or down as appropriate.  I never press F3 because the default calibration is 2.00.  

  5. Connect to Zwift and enjoy the ride.

  6. Each new ride, I inflate the tire to 100psi.  Since I haven’t removed the bike from the trainer and I haven’t changed the tension knob, the computrainer warms up and settles into a 2.00 calibration as I ride.  

  7. I recheck calibration about once a week but doing a traditional coast down.  Otherwise, I enjoy just logging into Zwift and riding knowing that the calibration will take care of itself.

Hope more details helps.

okay.  so you do leave the pinch roller engaged.


fwiw, this method isn’t foolproof.  I’ve accidentally experienced this on a few occasions where I’ve been in a rush at the end of a ride and forgotten to turn everything off.  I still go through the racermate calibration and end up with a value that’s off by more than a few hundredths.  I also end up with a soft spot in the tire.


That’s exactly why I check it periodically.  Especially before critical workouts and group rides.  

What number are we supposed to calibrate to?

I’ve read between 2.5-3.0 (pounds of pressure)

Elsewhere I read 2.5 - 3.5

Elsewhere 1.8-2.5 (what I have been doing until now)

The ideal press on force is the least amount that enables you to ride without the tire slipping.  The calibration routine will work correctly for any force value between 1.0 and 5.0, but the higher the number the more friction and tire wear you will experience.  I personally find a value around 2.20 works very well.


If you’re going to do a sprint workout, you’d like calibrate to something between 3 and 4; seated workouts are btw 2-3…generally.

That said, I usually just air up the tire to 110, count the number of half-turns to about 8 and use that unless it’s horribly out of spec.