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Zwifters

2 lurkers | 71 watchers
Feb 2021
11:15am, 15 Feb 2021
7,378 posts
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Northern Exile
Interesting BG. I can't say tyre pressure have been an issue (yet), perhaps that's something I should check. I have a Minoura v270 and a Tacx Flow, I've got a "proper" training tyre on one and an old Conti GP on the other, the only time I have noticed any slippage is when going from very low cadence to high in a sprint and it's only momentary. I will check pressures today!!

I would love to know "real" figures on a direct drive unit, but I guess as long as I keep a constant baseline I'll get the training benefit? My wattage/kilo seems to work out right there in ballpark with riders of a similar capability to me.
Feb 2021
11:15am, 15 Feb 2021
681 posts
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Big_G
My own previous post prompted me to actually reset the power numbers, which was easy to do on a Mac/PC. In case anyone is interested, just delete the "cp" folder in the Zwift folder structure on a Mac/PC. For Apple TV/iOS, I think you need to delete and reinstall the app.
Feb 2021
11:16am, 15 Feb 2021
7,379 posts
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Northern Exile
p.s. I should say that both the dumb trainers above are quite old
Feb 2021
11:28am, 15 Feb 2021
682 posts
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Big_G
NE, yes, I think that as long as it's consistent each time it's good in terms of tracking progress etc. I had an old Tacx turbo with a training tyre and although I had set it up correctly, it was a manual process to bring the roller up to the tyre, and there was no app or anything to calibrate it. My Taxc wasn't one of the models that Zwift supported directly, so I had to set it up as an unknown trainer (I think was the phrase they used), which meant that Zwift didn't have the power graphs etc for my model. Eventually, what I did was set it up in a way that I thought was correct and repeatable, and then just ensured the PSI was the same each time I started a ride so at least it was consistent. But I know for sure that I cannot do 400W for 1-min, which up until a few mins ago Zwift was saying was my best effort. On the other side of it though, in the game with my dumb trainer it wouldn't go past 400W (Zwift limited it to 400) even when I put a lot of effort in for a short space of time, but I know I can go quite a bit above that for a few seconds of hard effort at least.
Feb 2021
12:04pm, 15 Feb 2021
13,518 posts
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larkim
I've no idea at all whether my Zwift-power numbers are anywhere near to the real world, but at least they are consistent - I think.

I've not done any comparison over time, but as zwift distances and speeds are route dependent I'm not sure there's an easy way of comparing. I could just use my watch to log the activities simultaneously as that would give me wheel speed vs power which ought (in principle) to be consistent. There's no resistance dial on my Crono Fluid so the resistance is what it is, but I've read that as a fluid heats / cools etc it can give variable results.

If anyone has a spare powermeter lying around the house unused I'd happily test it out :-)

I've also not fiddled with tyre pressure, but *I think* it is less of an issue on mine as the trainer doesn't have a fixed triangle, it allows my weight to press down on the wheel onto the roller so (within reason) the speed / power relationship should be fairly consistent.
Feb 2021
12:07pm, 15 Feb 2021
13,997 posts
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Yorkshire Pie
I've never compared my power meter against the turbo but the power numbers on the road are broadly consistent with the turbo (Neo). The speeds on Zwift are a fair bit faster than I manage in real life.
Feb 2021
12:24pm, 15 Feb 2021
7,380 posts
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Northern Exile
Yeah, as Larks says Zwift distances and speeds are route dependent so it's hard to give a spot-on accurate assessment with a dumb trainer. My Wahoo speed/cadence sensor is bluetooth and ANT+, so it connects to my iPad for Zwift proper and also to my old Garmin 910XT, so I can see the disparity - I just record it as a normal ride on the Garmin. For what it's worth, the ANT+ also connects to a Bontrager head unit and gives me a real-time speed independent of Zwift .... ANT+ is not like TCP/IP, it's a one way broadcast (i.e. like UDP) so connects to as many devices as are in the vicinity.
Feb 2021
1:26pm, 15 Feb 2021
2,042 posts
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MudMeanderer
My power and time on Alpe D'Huez and Alpe du Zwift were fairly well matched based on the readings from my power meter and the current turbo. I expect would match less well on heavy Yorkshire roads!

The old wheel-on turbo was wildly optimistic in its power estimate for me; it gave me a sustainable power to weight Pogacar would be happy with! I wasn't using Zwift then though, so it was less of an issue.
Feb 2021
1:50pm, 15 Feb 2021
13,519 posts
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larkim
I just wish power meters were more reasonably priced! My engineering-minded BiL pointed out that as they are actually just little more than a strain guage there really isn't a good reason why they should be quite so expensive - but they are!

I'd borrow a set of pedals from a relative, but as they ride "proper" cleats compared to my MTB SPDs even that won't work as a cheap option to give myself some data.
Feb 2021
1:58pm, 15 Feb 2021
9,229 posts
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simbil
You can rent a powertap wheel cyclepowermeters.com

Mate did that for a couple of months before getting hooked on power and just buying one :)

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