LexRides

[chadwick2wheels]

ive heard there is a website that shows you the exact gear ratio to use depending on the length of your rear triangle or dropouts or something to ride fixed with vertical dropouts...

does anyone know what it is?

basically, i have a road frame i'd like to ride fixed on but don't know how to make it happen.
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The sound of a car door opening in front of you is similar to the sound of a gun being cocked. ~Amy Webster

[elzie5000]

http://www.eehouse.org/fixin/formfmu.php

There are other options. Eccentric hubs and bottom brackets.

Or you can usually get really close using a half link.

[chadwick2wheels]

thank you sir
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The sound of a car door opening in front of you is similar to the sound of a gun being cocked. ~Amy Webster

[alex]

the problems with calculations - there's lots of room for mistakes. you could measure wrong, or your chain is stretched a little, or even the chainring teeth are worn. mostly though, it's almost impossible to measure accurately. So once you find the perfectly calculated combo, you still might have to go up or down a couple teeth.

here's what you do:
put a fixed wheelset in your dropouts. put on a chainring. put on a chain and take as many links out as you need to get the chain as small as possible without being too tight to fit on cog & chainring.

if you are lucky the chain will have perfect tension and you can ride off. most dropouts, even if completely vertical, can be moved up and down a little to give more or less tension. If you're way off, you need to adjust the chain or number of teeth in your cog/chainring, or both.

A chainlink is 1". a difference of a full link moves your rear axle 1/2" forward or backward. a half link moves the axle 1/4"

each tooth moves the rear axle 1/4" as well, so if you add 3 teeth (on the cog or chainring or both combined) it will move the axle 3/4"

armed with this information, a chain tool, and a handfull of chainrings and cogs you should be able to figure it out. the computer shit just makes it more complicated.

and, once you find a gear ratio that gives the right tension you can change the ratio as long as you add or subtract teeth in multiples of four, or multiples of two with a half link added or subtracted.

i've done this with all of my fixed gear & ss bikes

good luck
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How about, "Can you NOT rip a giant hole in our downtown and erect a big goddamn penis full of crappy chain businesses?"
-F.L.

[brokebike]

in my experience with half links, it seems to be easier to find them readily available in 1/8", but not so much with 3/32". Then again, I usually run a good 'ol SRAM PC-1 on anything fixed or SS. They're sturdy, reliable, and a bit more forgiving if your chainline is not so perfect. Most shops should at least have a 1/8" half link laying around...
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[chadwick2wheels]

geez. sounds harder than i thought. i might be asking some of you guys for help when i get to that point.
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The sound of a car door opening in front of you is similar to the sound of a gun being cocked. ~Amy Webster

[elzie5000]

Its a lot easier to do it than to explain it.

Do what Alex suggested. Build up the drive train you want using your own or borrowed parts. If the chain is too floppy but taking out a whole link makes it too tight, get a half link or go up a tooth.