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fixed gearing, why small chainring?(7 posts)

fixed gearing, why small chainring?Qubeley
Oct 26, 2003 8:33 AM
I am just curious, why do people run small chainring like 39-16, 42-18, not 48-17 or 50-18?
minor correction..Qubeley
Oct 26, 2003 8:36 AM
obviously 50-18 is a taller gear than 42-18.
What I meant was: with same gearing inch, why do people choose to use small ring over big one.
I know this one!LC
Oct 26, 2003 9:46 AM
They do use the larger chainrings on a pure track bike. Most fixies on the road are just put together with whatever you got laying around or can get cheaply. 39 or 42 chainrings are what most have already, not 48 or 50T. It is also hard to find good cogs larger than 17.

There is also the issue of weight, especially rotating weight which is more of an issue at the high rpm's fixed riders see regularly. You would have a larger chainring, bigger cog, and longer chain which all add up.
another small advantage...jtferraro
Oct 26, 2003 5:53 PM
By running a smaller chainring, you're able to move the rear wheel more towards the rear of the bike, which allows more chainstay clearance for larger tires and maybe fenders.

not jimbo
Oct 27, 2003 2:01 PM
If you add links to the chain it doesn't matter what the size of the cogs and rings are.

Also rotating weight of this amount would never matter much.

I went to a smaller chainring, had a link removed, and...jtferraro
Oct 27, 2003 3:14 PM
the rear wheel still moved rearward a tad.

I run a 48 ...Humma Hah
Oct 26, 2003 2:35 PM
... but you can get trapped with fairly tall gearing with the large chainrings. Small rear cogs, 18T and less are more readily available. With the larger chainrings you may not be able to gear for hills.