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#1
03-11-2008, 02:27 PM
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Fixed Gearing Combos
This falls into the category of "definitely-newbie-question" so I beg everyone's indulgence. I suspect the answer must be too obvious since I've found almost no mention of it on the interweb (except, of course, Sheldon Brown).
Currently/slowly building up a '68 Schwinn Paramount as my (first fixed-gear) commuter. I've been diligently making my way through the fixed-gear threads and I'm confused as to what the main rationale would be behind choosing, say, 44/17 vs. 46/18 vs. 49/19 since they produce roughly the same gearing ratio (+/- 2.55) and roughly the same gear inches. I understand that, given the ratio being the same, the combo with larger ring/cog should cause less wear/tear on the drivetrain. And of course a larger ring can produce a lot more speed if mated with a small-enough cog. But if the same gear inch can be produced by multiple ring/cog combos, how does one decide to go which way? Thanks. 
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#2
03-11-2008, 02:30 PM
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If you like to skid, the odd combinations will spread the number of bald spots
around the tire. otherwise, gear inches is gear inches... doesn't matter how you get there. -g
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#4
03-11-2008, 02:53 PM
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I use a 48-18 set up on my fixie, used to run a 16 rear cog. It can be real tough on my commute home which is up some serious hills but I like the gear ratio just fine.
John
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#5
03-11-2008, 02:59 PM
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Quote:
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#6
03-11-2008, 03:01 PM
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Good points so far, and I'll add that bigger sprockets are more mechanically efficient.
Very frequently the choice is driven by what is available when doing a conversion, e.g. 42t ring from a road crank or 48t ring from a track crank, and then folks go from there.
__________________
Jeder geschlossene Raum ist ein Sarg.
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#7
03-11-2008, 03:07 PM
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Check out the link below for direct access to the downloads. Or just go to their website. It is kinda dedicated to the cause.
www.fixedgearfever.com http://www.fixedgearfever.com/module...name=Downloads
__________________
A Whiz in the Biz
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#8
03-11-2008, 03:10 PM
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I ride 45/17 during winter (69 inches) and bump up the front ring during the summer. 17 gives you the most skid spots (prime numbers are what you are looking for) and though I don't skid like a kid, I did find that 45/15 was stupid as I got a bald spot as large as the one on top of my head. I personally think that 17 makes the front ring easy to keep the gear inches between 65-90 than say 13 or 19 do.
I'd love a '68 paramount....
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#9
03-11-2008, 03:10 PM
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bro keep it cheap i run with a 50 x17 one my road bike and a 40 X 14 on my mt bike both are fixed keep it real cheers
__________________
Life is perfect when you Ride your bike on back roads
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#10
03-11-2008, 03:57 PM
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I run a 42/16 on my fixie. It's just about perfect for the rolling/flat terrain around here.
You can go here and get all your gearing options checked out: http://software.bareknucklebrigade.c...it.applet.html You have to have Java enabled on your computer to run it, but that's a free download. The second tab on the applet gives skid patches for given gear combos. Enjoy! Mike in AR
__________________
2013 Serotta Fondo Ti w/Enve fork
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#11
03-11-2008, 04:15 PM
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The different gear combos will result in slightly different effective chainstay lengths, if you're sensitive about such things. Probably not a big deal for an older Paramount, they have nice long slotted dropouts, iirc.
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#12
03-11-2008, 04:59 PM
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Quote:
__________________
Eat the nouveau riche! Those who cannot remember the past are condemned to repeat it. - Georges Santayana
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#13
03-11-2008, 05:10 PM
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Quote:
I'm running a 50/19 combo. about 71ish gear inches. Good enough to get me up anything up to a 6% average grade before discomfort settles in.
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#14
03-11-2008, 06:43 PM
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Quote:
most people work out what gear they want (say 70inch) then eyeball the bits they've got lying around... uh, a 42T chainring... well, that'd mean a 16 sprocket, which DuraAce just happen to make in 3/32, so if I buy that and a 3/32 chain I'm good to go. Later on they get to spend money replacing bits and tweaking (fettling in the UK, mostly). It ain't rocket science and you don't need hoooey about increased wear in the drivetrain and tighter radii inefficiencies from smaller chainrings. The differences are negligible, the weight savings by going smaller are miniscule, the wear rates unmeasurable. What matters can be the proportion of change in ratios and the wear pattern on a tyre if you're the sort of muppet who likes to skid.
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