True
i believe you just need a speed sensor.
if your trainer is already a recognized option in zwift, you just tell it which trainer you’re on and put a speed sensor on the rear wheel and pair that.
i’d recommend finding a bluetooth compatible speed sensor for ease of set up - othewise you’ll need to zwift on a laptop with an ant+ adapter. if you grab a bluetooth sensor, you can use an ipad or iphone for zwift.
if you’re gonna use a laptop, you may still need a dongle depending on your set up. macs usually have BTLE already, but most windows laptops just have bluetooth 2.0 and need a BTLE dongle - but those are like $20-30.
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oh THIS is how all these people without power meters are zwifting
that’s genius
yeah - they plotted the resistance curve for certain popular trainers and use that combined with wheel speed. it’s not nearly as accurate, but it lets you zwift without spending hundreds (so a good choice for zwift because more $$ from more subscribers).
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The kinetic trainers have a thing you can stick on the trainer that tracks from than side too. It’s just a speed sensor pretty much. But options.
I posted that way back up. But I figured it could do more. It detects the speed of the flywheel, but it also knows how much work it takes to make the wheel go that fast, so it can determine watts from that, right?
yeah, but it’s still highly estimated. tire pressure, tire rolling resistance, etc play a huge factor. it’s all based off the assumption that you have a properly inflated smooth tire and that it’s correctly installed (i.e. you tightened that knob on the back the right amount), and then you can estimate something that decently resembles actual watts. plus trainers heat up quite a bit which causes a pretty decent change to the resistance curve - so i’d assume these things are set up to measure accurately after warm up, so they may under report until that happens.
with smart trainers for example, they have to be ridden 15-20 minutes before you can do an accurate spin down, otherwise they overestimate, because the resistance goes down as they heat up.
Trainer resistance based power is a guess. A power meter tells your power: everything else is handwaving.
I don’t even like power meters, but it’s true.
Good enough to play zwift tho.
Y’all are right. I was thinking of cars for some reason. Where the power at the engine is pointless and it’s the power at the wheels that matter. Totally the opposite of bikes I guess. Sort of. If you’re not racing.
Direct drive trainer is where it’s at.
I had a smart trainer last year but it sucked.
Nah, not really opposite in this case. in the case of the bike, you can measure power at the pedals, cranks, or hub because it should in theory be the same - it should all transfer directly to the rear wheel and output the same power. It’s just measuring forces propelling you forward x speed (rpms in the case of cranks/pedals and wheel rotations in the case of a hub). You can also fairly accurately calculate power outside without any direct force measurement using wind resistance and a speed sensor - to a surprising degree of accuracy. I forget the name of the product that does this. Problem is it kind of goes out the window in off road applications.
Without a trainer with a built in power meter (the direct drive type actually measure the torque input to spin the flywheel), there can only be estimated guesses since the resistance is variable. There’s just a potential for a large amount of power loss (i.e. friction from your tire) or change in friction from heat (not really an issue measuring on your actual bike).
Now that there’s an 11 speed cassette on there, the chain rubs the seatstay end nub.
What can I do about it aside from limiting out the 11tooth cog?
New bike.
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Take a file to the nub?
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spacers on the hub?
File the chain?
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File the cassette?
convert to belt drive?
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Single speed?