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Anyone got any ideas this is annoying me.
Been merrily using zwift since about November. Got a tacx flow trainer and no access to a power meter.
Had 2 bikes on the trainer, calibrate both, number came out about the same when doing an ftp test (320-330W). Took my bike off the trainer to do some maintenance (headset bearing). Pumped up the tyre and put it back on. Re calibrated the trainer and now have massive power loss, down to 290FTP in a test. I don't feel ill so I'm assuming it is something in the setup. This is consistent as well, been struggling to hit the numbers all week, not just a one of ftp test issue.
Any ideas why it might have changed and how I might correct it back. Annoying because there is now no consistency in my training data and I'm going to have to readjust training peaks!
If the tyre was low for the first FTP test this can have a big effect on the power. Also are they both 29" or 700cc? Since I think Zwift still assumes 700cc wheels.
Edit: Also lots of issues and solutions are discussed in the zwift mega thread.
http://singletrackmag.com/forum/topic/zwift-my-journey-my-weight-and-my-fitness
zwift converts wheel speed to power, so your wheel speed is lower than it used to be.
So it could be a change in tyre pressure, it could also be due to a change in the tension between the roller and the tyre.
Zwift specifies (or at least it does for my trainer) how tight up against the back wheel the turbo roller needs to be.
I presume you havent changed anything else that could alter the wheel speed? like gearing or wheel size? Recalibrating the speed sensor could also cause it, ie is the speed sensor underreporting your speed, or was it over reporting it before.
so thats whats wierd. winter and summer bike when calibrated were about the same across 2 ftp tests. Take bike off and back on now it is different.
Will look at the mega thread...
Do you have sufficient data available in traces to be able to look at wheel speed for before and after? Maybe a garmin running at the same time?
Does the turbo have variable resistance? Might that have been knocked down a notch?
I'd assume there's wheel size calibration somewhere in Zwift for virtual power too. Has that changed? Maybe a Zwift update has reset it or changed the turbo type? Or maybe Zwift have updated the speed/power curve for your turbo? What's the turbo?
Tacx 2240 smart so it should be reading power rather than wheel speed? Will have a root around the settings see if it all looks right.
Ah right, a 2240 😀
yeah, wasn't expecting accuracy but lack of repeat-ability isn't great.