help with gearing
 

Hi,

I converted a Schwinn LeTour from the 80's to a singlespeed, and need some help with the gearing. It currently has a 52T chainring in the front, and 17t singlespeed cog in the rear. It it fine for flat terrain, but where I live has a lot of hills. In order to get the bike to go up the hill, i tend to pull up on the handlebars, and wound up hurting my shoulder. Would switching the rear cog to a 20t make a significant difference? This would probably involve shortening the chain too, right? Thanks,

Dave

I'd look at switching out the chainring first. 48T perhaps? I'm currently running 44/18.

The chainring would probably be easier since i don't have the rear cog tool. I guess the only way to figure out what size is more or less trial and error? Was thinking maybe 46t since so many singlespeeds/fixies have that. The current chainring is 130mm bcd with 5 bolts, but I see there are 1/8" and 3/32" options? Is that referring to the chain width? Thanks,

Dave

Yes, increasing the number of teeth in the rear will make a big difference. You may need to increase the chain length, not shorten it, but adding three teeth to the cog will only move the axle about 3/8 of an inch, so you might not need to lengthen the chain if you can move the axle that much in the dropout.

Unfortunately I don't have any more clearance for the rear axle (the opening faces toward the front wheel and is close to the end). Is there a way to tell if I have a 1/8" chain or 3/32"?

Dave

You can add a full link to the chain, which will move the axle back 1/2 inch to compensate. Measure the inside width of the inner link to determine the chain width (1/8" or 3/32").

chainring size
 

Hi,

Just confirmed that the chain is 3/32 of an inch. Spoke with my LBS tonight, and they are saying that I won't be able to go with a gear less than 48t since the bcd on my crank is 130mm.. Any idea why that would be?

Dave

That's completely wrong.

oddly enough he showed me a 45t chainring after that lol. Is the chainring swap pretty easy? Looks like I have to unbolt the old chainring, bolt on the new one, then cut the chain, and move the master link. How is the right chain length determined?

Dave

Because your LBS has no clue.

If you're going from 48 to 45, you may not need to shorten the chain at all. If you do decide to, the way I generally go is to install the wheel, fasten it in the middle of the dropouts, wrap the chain around the cog and chainring, and pull it not quite taut to find a good length.

^He's dropping form a 52 to 45 tooth chain ring, so he'll probably need to drop a few links. if it's a a conversion it can sometimes be tricky to find the right tension though. hopefully you've got some semi-horizontal or slanted dropouts that give you a little room to play with chain length.

Removing the chain ring bolts is all you have to do to swap out a chain ring, allen wrench and a screwdriver should be all you need.

Depending on how long his drop out slots are, he may not need to shorten his chain to go from 52 to 45 since he said he was at the front of the drop out with the 52.


You'll be going from 81 inches to 70 going from a 52/17 to a 45/17. A dramatically more hill friendly gearing. You can calculate gear inches here: http://allcitycycles.com/ click on "GEAR" on lower right

I run a 48x17 on a commuter and 44x15 on another. I like both on flat to rolling terrain, the 48x17 is easier to spin and could be the simplest solution for you. Found an origin8 48t new for about 12.50 shipped (sale), not the prettiest ring but must say it is machined well and has zero offset/wobble.

Where did you find the 48t? Hard to beat that price!

Dave

Hey

You can find it on ebay, guy has raised his prices since August but just watch them as he dropped it on sale when I picked it up. Total was 13.04 shipped, I was off a few quarters! 110/130 ring. Pretty common to find them sub 20 though. For the price I recommend it.

Probably one of those dual BCD "rocket" rings.....

I set up a converted Panasonic with 52 x 20 gearing for a friend who is not a strong rider and lives in a hilly area and he loves it.

gearing
 

Hi all,

Thanks for the help.. Bought a 45t gear from amazon, and got it installed on the bike. It looks like if I take 1 link out and push the wheel to the end of the framestay it will work (hopefully there is enough tension)! I'm down for the count right now with a hip problem, will post later on how this gearing works :)

Dave