SS conversion issues - alignment :(

[Bro]

Hey all, just came across this forum

I recently received a 90's Schwinn Worldsport 7spd. Since I already have a geared bike, I decided to convert the Schwinn to a single speed.
I managed to get all of the components except the rear cogs off. I removed the smaller chain ring and switched out the chain ring bolts to shorter versions. I shortened my chain and fitted it onto my cog with some good tension.

Here's the problem, when I turn the crank, I get a subtle resistance and then, the chain pops onto the lower cog and then eventually falls off...On top of that, my rear wheel is pulled to the right. I did a lot of adjustments like adjusting my wheel in the rear drop outs and moving my chain ring to the inside of the spider. (btw, I run with a 52t-19t)
Still, I run into the same problem...

If anyone has any suggestions on getting the right alignment, that would be awesome. I want to start riding again!

 

[garage sale GT]

What sort of rear wheel do you have?

How far away from the centerline of the bike are the front and rear sprockets in millimeters?

 

[Bro]

I have a stock 700c alloy wheel with a Shimano freehub, I'm not sure about the 2nd question....I'll measure it soon I'm still a noob :s

I'll line up some pictures this weekend. Thanks for the reply!

 

[alfeng]

I have a stock 700c alloy wheel with a Shimano freehub

When you have a Single Speed (or, a bike with only one cog on the rear wheel like a 3-speed bike), you want the chain to run parallel to the center-line of the bike OR top tube ...

You should either restack the cassette so the 19t cog is in line with the chainring (usually, mounted on the inside of the crankarm's spider). On a freehub, usually the excess cogs are removed because they are dead weight and replaced with spacers.

You can buy extra spacers (not that cheap, but not that expensive) or you can cut some from some PVC tubing whose inner diameter (1 3/8" ID?) will sleeve over the outer diameter of the Freehub body.

 

[garage sale GT]

Why don't you run the chain around whichever cog is directly behind your chainring just to verify that that's the problem? Then you can more confidently spend some bucks getting the chainline correct. You could even put the ring back on the outer position on the crank if it resulted in a straighter chain.

If you have a uniglide freehub, you can buy spacers to fill up the rest of the freehub as well as fine tune the location of the sprocket.

There's a ghost of a chance that something is loose or broken, such as a cracked frame or axle, and you are ghost shifting the bike by bending it with torque. Or maybe the frame's bent.

 

[Bro]

Thanks for the replies! I plan on getting a single speed cog kit. I haven't found any 19t cogs yet >.<

I'll make sure to run the chain parallel to the center line and in line with the chain ring and see what happens. Hopefully nothing major is damaged! I don't see the chance since it has been running perfect before I tore it apart...

Hopefully the problem will be solved once I buy some spacers and separate my cog. I did buy a new chain (1/8th) which is too thick for multiple cogs. I'll use it when I get everything separated. I can do a test with my stock chain and shorten it for the cog that's aligned with the chain ring and give it a test ride.

 

[alfeng]

I plan on getting a single speed cog kit. I haven't found any 19t cogs yet >.<

Instead of the 52t chainring & a 19t cog, while the gearing would be a little different, you could consider using a 42t chainring & a 15t cog OR a 39t chainring & a 14t cog to achieve almost the same gearing.