On the Topic of Calibration

I have seen lots of discussion on calibration.

Here is an interesting way to incorporate this into Zwift… here it goes…

  1. At the start line, there is a Zwift warm up tent / area. All players can warm up there as long as they want i.e. get their initial calibration. And once calibrated, they can jump on the course or get transported to their friend’s location.

  2. After 1 lap, this applies for CompuTrainers, your tires are all warmed up and you are required to pull in to the “warm up” area and re-calibrate. I find that when I use my CT after a 9 minute warm up, my CT calibration can very as much as 0.75 - 0.90. But once the tires are warmed up (and the air inside) the calibration is rather consistent.

  3. Any rider can pull into the “warm up area” , even if all they want to do is wait for a buddy and not re-calibrate. One thought is that, the rider presses a key and when they pass the station they just roll into the warm up tent / area.

  4. The warm up area also doubles as a chat room. Separate from the coffee house char room :slight_smile:

  5. You can debate on this aspect, but anyone that wins a Sprint/KOM/Orange should be subject to a re-calibration test. Maybe it is mandatory or by rider protest. Just a thought.

.75 to .9?? What kind of tire are you running and what wattage are you riding at during calibration?? Although Ive seen as high as 15 inutes at 150 watts recommended before calibration I have never ever done that… Ill do maybe 5 minutes @ 150 watts max with a conti trainer tire and run around about a 2.3 to 2.5 presson force and Ive never drifted more than about .2 in 10 years… I find the conti tires aren’t as good as they used to be though… I delaminated another one last week… first one lasted a few years… this one has only lasted since fall…


With the CopmpuTrainer the electronics controller on power up defaults to a 2.00 resistance calibration. I’m not a 100% sure of the meaning of the value. But I do know that you apply some resistance to the rear tire and spin up the bike to 25 mph and then let it spin to a stop. then the system is calibrated. typically after the 1st time I get a value of 2.80 - 3.30. Something around there. At this point I do nothing other than get on the bike and ride for 8-9 minutes, This warms up the air and rubber of the tires. Then I put the CompuTrainer back into calibration mode. I’ll do the spin up to 25 MPH and let is spin to 0 mph . Now the goal is to adjust the tension on the rear tire to get the calibration to a value of about 2.50 +/- 0.10.

If one doesn’t do the calibration then essentially they can cheat by faking the system that they have the tons of load of the rear tire when in fact just the opposite can happen and the rider takes off lots of tension, so that they can spin really fast w/o any resistance.

So calibration of a CT is essential. I have done many indoor CT Time Trials and they all insist that you warm up the tires and so that the CT can be calibrated accurately.