Can tyre brand/size affect Power output in Elite qubo power mag trainer

I was using Vittoria zaffiro 700x28 for trainer earlier and with that my FtP was 167W. After replacing that with schwabe insider trainer tyre 700x23, my ftp dropped to 129w. What could be the cause of this drop when there was no change in my health or exercise pattern? Has anybody experienced similar issues? Note that The power wattage is calculated by the trainer ie i dont have a power meter.

Yes, tires can and do have impact on power reporting on wheel-on smart trainers. If possible, you should be calibrating the trainer with the new tire, and then perform an FTP test of your choice on the new tire.

This should get the trainer to report the best power data that it is capable of producing. Changing the tire without the calibration or new FTP test will likely lead to undesired results in training.

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Thanks for your response.

I did try calriberating the trainer after the tyre change using the trainer’s procedure for caliberation. The Caliberation procedure in TR app does not work for my trainer ( it just keeps saying caliberating…)

Is there anything else that I need to do?

There is a process you can use to calibrate it using known values and the Elite app but a friend of mine has still seen a variance between his trainer and a power meter.

Key with a wheel on trainer IMHO is consistency. Use the same tyre at the same pressure with the same tension from the roller (if adjustable, can’t remember on yours).

The number given might not be accurate but as long as it is consistent it is fine for training with.

I did experiment with a Tacx Genius wheel on and tyre pressures versus an FSA power box power meter. For me 100psi in the same cold tyre and never touching the tension once set (set after 30 mins, totally warmed up) gave me repeatable results that were within 5% or so of the power meter. More importantly they correlated at enough points of the power curve to be useful.

Thanks, Yes I do make sure keep all the other parameters same ( tire pressure/ resistance levels) before doing the workouts or ramp test. The ftp value that I am getting now with the tire change does not affect my TR workouts as I am doing those with the same tire. But If I have to participate in race on other apps such as Rouvy, the power o/p will affect my speed & timings which is my main cause of worry.

Sad to say but I can’t see the cheap Elite trainers being fit for that purpose. Anything wheel on is hard to keep accurate at the best of times (but should be able to be consistent).

My Tacx I could make over or under read by 20% quite easily (under more often than not) until experimented and had a set routine.