Singlespeed & Fixed Gear - Big-Big or Small-Small drivetrain fixie?

I can get the same gear ratio running a 52 big ring and a 13 cog as a 40 ring and a 10 cog, or a 36 and a 9. Or hell, a 60 and a 15. I'm building my first fixie, and wondering what all you experienced fixie riders have to say on the big-big / small-small drivetrain issue.

Medium seems to work well. I run 46x18 right now. Rode 46x17, 48x17 and 48x18 too. All works quite alright. Go with a medium front chainring (somwhere in the fourties), because if you go larger you might have some clearance issues (chianring scratching frame). Plus 46,48,45 etc. are easy to find most of the time. If you go under fourty you will need a really small cog which might rub on your hub.

I wouldn't want to put to big of a cog on the wheel - I'd worry it would bend.

Maybe that's just me, though.

biggers cogs spread the wear over the teeth. [i haven't explained that spectacularly well.], so your cogs will last longer [in theory]. you'll also have more teeth engaging with the chain at any one time, so you'll be less likely to throw the chain.

as far as disadvantages go, i'm not sure that flex would be an issue with a straight chainline, [anyone beg to differ?] so the only one might be weight.

personally i'd go as big as you can until you get chainstay clearence issues.

fsnl
sparky

From the fixed gear mailing list: "Actually, medium is best. If you go too small, stresses on the drivetrain increase, parts wear more rapidly, and wheel slippage is more likely. If you go too big, it's just excess weight. Generally chainring sizes somewhere in the 40s are good." I think cogs under 12 teeth are theoretical arguments at best, anyway, due to the lockring clearance issue.

But the real issue is why the h3ll would you want to run 52-13? Are you Paul Bunyan?

well, out of all the gear ratios you mentioned, two are impossible: nobody makes a track cog with fewer than 12 teeth. and 52/13 is a bit much, especially for yr first fix.

and 52/13 is a bit much, especially for yr first fix.

...unless you're going to race and you've got monster thighs!

i think my gearing is 50something x 16. its whatever the biggest cog on a multigear bike is, maybe 53, i never really got bored enough to sit there and count the teeth

I switched mine back to 46*16 for the ride into work tonight and got here faster than 46*14. Go figure.

biggers cogs spread the wear over the teeth. [i haven't explained that spectacularly well.], so your cogs will last longer [in theory]. you'll also have more teeth engaging with the chain at any one time, so you'll be less likely to throw the chain.

as far as disadvantages go, i'm not sure that flex would be an issue with a straight chainline, [anyone beg to differ?] so the only one might be weight.

personally i'd go as big as you can until you get chainstay clearence issues.

fsnl
sparky

Amen. I run 50-18 to even out the wear and chain stretch.

theoretically: less friction and wear (read: more efficient) with bigger sets.

empirically: aint no dif.

If your using road cranks like I am then chainline can be an issue. I was running a 46/15 and the 46 had to be on the outside of the crank spider thus the chainline was off a bit. I put a 42 which fits on the inside and the chainline is absolutly perfect. Incidentally I like the 42/15 a hell of a lot better anyway...

Like Baz, I too will be building up a SS/Fixie for the fall months ahead. So the average or usual gear combo is like a 42/16?

well, out of all the gear ratios you mentioned, two are impossible: nobody makes a track cog with fewer than 12 teeth. and 52/13 is a bit much, especially for yr first fix.

there's somewhere on SB's site where he talks about trying to find an 11... I have a 13 on one bike and the clearances seem so tight.

anyway, I think a larger cog just feels smoother. plus you can run a big ring up front, which serves as an emergency pipe cutting tool, or impromptu kindling splitter.

A smaller drivetrain is obviously lighter, and possibly stiffer and more responsive(better for sprinters), at least that was the idea behind the dura-ace 10 drivetrain. Basically everything's just smaller. Was on my first trackbike, works really well, still have the bike but don't ride it anymore because the parts are too hard to find.

These days though I run a 46x18 on nyc streets, and a 48x14 on the track. I think a big reason to go with a medium-ish gearing is that you generally end up with medium-ish chainrings, which are pricey to replace.

I run a 48x18 on one ride and a 49x 20 on the other, I ease along on both about
20mph most any time i check the speed. Funny thing is I had 48x21 on at one time
and ran along at 20mph w/that gear combo aswell. My legs just spin more and I
got more exercise, mostly ran that gear when I rode w/a girl friend. Here in
Williamsburg Va. there is alot of rolling terrain and w/the 48x21 you will learn to spin
a nice round pedal stroke.

My 52x16t sure looks more impressive than the one running a 42x16t. :D