What is calibration?
One of the best features of a smart trainer is their ability to provide power numbers. And when it comes to power, nothing is more important than accuracy.
With a smart trainer, the heart of power accuracy lay in calibration. This calibration process is especially important with smart trainers that have a tire-to-roller interface, also known as a wheel-on trainer. The Magnus is an example of this type of smart trainer.
Since each bike set-up is different, each bike needs to be calibrated with a smart wheel-on trainer to ensure the best possible accuracy. This is because no two bike set-ups are the same as each uses different tires, rims, and recommended tire pressures, all of which play a role in dictating the rolling resistance measured by the trainer.
It’s this varied rolling resistance that the roll-down calibration is measuring and accounting for when calculating power readings, or wattage. Since rolling resistance can change from session-to-session, or even within the same ride, we recommend performing a calibration as frequently as you wish to keep your power numbers as accurate as possible.
You may notice that this recommended calibration protocol is for wheel-on smart trainers only. This is because direct drive smart trainers do not need to be calibrated as often as wheel-on trainers, as there is no tire-to-roller interface. The direct drive design reduces the variability in rolling resistance from ride-to-ride. While you can still calibrate direct drive trainers as often as you would like, often a weekly or even monthly calibration is sufficient.
When it comes to calibration your wheel-on smart bike trainer, there are two ways to go about this important process.