Calibrate Computrainer in-game

I created this request by accident, while searching for an update to this feature request, not wanting to create a duplicate. Since I can’t delete it, I’ll let it stand bc this issue is driving me nuts.

I calibrate my Computrainer 3 times/ride. Once before I ride, once 6’ in, and once before intervals. Since the inception of Zwift beta, I have to yank the USB cord (which often creates a power spike that I have to manually remove from the file later), and GET OFF THE BIKE to plug it back in before Zwift will find and repair the Computrainer. 

Recalibration in-game without yanking cords is possible, Ergvideo does it. Please add this!! It would greatly enhance my Zwift experience. 


Why are you calibrating so often?  Does your bike go on and off the CT between rides?  

I have a dedicated bike on my CT.  So long as my tire is inflated to the same pressure before each ride, my CT doesn’t need to be recalibrated.  I tend to do a spin down test maybe 2x per week, usually after riding when the load generator is warm.   My calibration is usually pretty close when I do this.  



Why wouldn’t you calibrate every day (after a warmup)? The CT is great for giving precise measurements if it is calibrated, why put up with “pretty close”?

If you ride frequently, you wouldn’t even have to pump the tires every time, just calibrate instead. You aren’t going to pump them as precisely as you will measure watts with a calibrated machine. I’d put my energy into calibration.


I’m a science nerd and a numbers geek. I love to mash the numbers in WKO4 and make graphs and see results and predict areas for work and target intervals. I don’t want to get Zwift jerseys or think I hit interval targets without knowing if my tool is measuring correctly. Instead of questioning if it is real, just calibrate and know. Garbage in - garbage out. Make sure you are putting good numbers into your model so you can be confident in it. 

I guess it depends on what you want to do with your data and how you use it. I have to remember that not everyone enjoys numbers and riding the same way I do, and as long as you are on your bike and happy, that’s what matters.


The press-on tension required will vary with tire pressure.   If I keep my tires inflated to the same pressure – 8 bars – and when I do calibrate the numbers are very close to the previous ones.  (I try to keep my press on force at around 2.75-3.00). To the extent the numbers are slightly variable, they are no less variable then when I perform sequential roll-down tests one after another when the load generation is fully warm.  I value the numbers, but I’ve been using my CTs for decades, and I’ve come to the conclusion that while they are good, they are not perfect scientific instruments.  You just want to be as close as possible.   

To the extent your seeing press-on force numbers that vary, I’d bet it’s because your load generator and tire are not suffiently warm before when you calibrate before riding, and 6 minutes isn’t enough to get them to operating temperatures.  This is why I do tests after my rides/workouts are over and everything is warm. 



I use a CT as well and agree with Doug.  I’m also a numbers geek but I’ve done my testing and if you get the CT calibrated properly once and just pump up your tires to the same pressure, ideally around 100psi, it is spot on after about 10 minutes of warm up time.  This naturally relies upon keeping the bike on the trainer between sessions, but if you can do this it is quite easy.

All this aside, I do think Zwift would be wise to implement a calibration routine into the application.

I turn my CT load generator off when not in use. When I turn my load generator back on, the calibration automatically returns to 2.00. I prefer the press on force to be a higher number, so if I did not recalibrate, it would be incorrect.

Therefore, to calibrate by tire pressure, I would either have to find the perfect tire pressure that results in 2.00 when the tire is warm, or calibrate the CT and then never turn it off. I prefer to simply recalibrate, and to do so a few times. I’ve been calibrating this way for 10+ years, and other programs such as ErgVideo have accommodated this. 

In any case, I accept that some people prefer to somehow calibrate their tire pressure rather than the CT, but I believe that those of us who prefer to calibrate the CT itself should have the ability to do so in-game, which is what this post is about. I would appreciate support for this request.

I don’t think there is a way to calibrate “in-game”.  As a Computrainer user for over 20 years I completely agree with Duane and Doug.  There is really no need to turn the LG off.  If you have calibrated properly (and you have) the only variable is tire pressure.  I use 110 psi with a Conti trainer tire.  I get a consistent 2.10 of press on force.  The beauty of this method is that you can get on the bike with no fuss and be calibrated every time.  I do still calibrate in-session with ErgVideo at times to ensure I’m at the press on force I want - I do that because we can with that software.


The nature of Zwift may not lend itself to in-game calibration.  Imagine tapping that button on the mobile app in error during an event…

You just heard it from the proverbial horse’s mouth.  

Ray – I’m sorry to hear the news about Computrainer.   I’ve had one of my two current CTs for over 15 years and it’s been bombproof.  I think I’m going to purchase a few stereo cables, cadence sensor cables and other spare parts to stash away for future use, just in case.

Good luck with your future endeavors.  

I don’t work for RacerMate, I’m just their forum “guy”.  What you’re referring to is this -

It is unfortunate that this happened, I agree in getting some spare parts for the future.

That is correct, there is not currently a way to calibrate in-game. That is the feature I am requesting (hopefully it is posted correcting under “feature requests”). It doesn’t have to be on the app where you can hit it accidentally. It can be in the computer menu and take a couple of clicks. This is what I’d like to see: open the menu from the desktop, click a button that says “recalibrate”, do a spin down, and hit “reconnect”. This would eliminate the need to pull the cord from the computer. This is done from the computer platform, not the app, so no danger of hitting it by accident, because the menu is not normally open. Same as if you wanted to change kit or your name or something.

I do turn off equipment that is not in use as a general rule (not going to justify that). I’ve also had a tire pump gauge go bad with bad consequences on the road (overinflated tire blew off the rim, replaced the gauge to fix it). 

I see that there is opposition to a in-game calibration option, so I suspect it is unlikely that Zwift will add this feature.

I’m very sad to see Computrainer go out of business. I’ve already ordered a stash of cables. I hope we’ll see the extended warranty program happen.


I see the new Membership Subscription is live!

A lesson from trainer road might be in order here. And trainer road, all a rider has to do is press the F3 button on the computrainer controller, pausing the workout and allows a spin down calibration. Pressing F3 again resumes the ride. Easy and seamless as can be. I can’t imagine this would be that hard to apply to zwift.

still looking for a way to re-calibrate 10’ into the ride…  please?