Singlespeed & Fixed Gear - Gearing?

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Chop
03-11-04, 09:15 AM
I've been riding an old "Columbia Commuter III" that I rescued from a dumpster. It was a 3 speed; someone converted it to a singlespeed.

It has a 48 tooth sprocket in front and 19 in back. Is this normal gearing for a singlespeed?


stevo
03-11-04, 09:29 AM
48/19 is a 2.52 ratio. Thats typical of a descent 'middle gear' for general purpose riding or training in most areas.

Truly though, only you can answer wether it fits your needs. Ride 2.52 on simliar wheels and see if it works for you.

stevo
03-11-04, 09:30 AM
just reread your post and see you've BEEN riding it. So, whats the verdicict?


Chop
03-11-04, 09:51 AM
48/19 is a 2.52 ratio. Thats typical of a descent 'middle gear' for general purpose riding or training in most areas.

That answers my question.

The gearing seems a little too high (hard) for me to get a quick start. But if 48/19 is a 'middle gear' it appears that I need to keep working on it and get stronger.

stevo
03-11-04, 10:11 AM
2.52 is pretty light; common among urban riders who sacrficie top-end for quick jumps off the ubiquitious lights. Unless your difficulting in starting is always uphill, then Id say yes, you need to eat your wheaties.

One other possiblity; I'm no 3-speed expert (thats 2 more than any bike I've ever owned), but is it possible that when the hub was 'converted', the internal
gering was left intact? If so, perhaps youre actually pushing much more than 2.52. Quick and dirty way to tell; borrow a multi-speed bike; set the drivetrain to (as close as possible to ) 2.52, and see how it feels relative to your bike.

jimv
03-11-04, 11:19 AM
[QUOTE=stevo]....I'm no 3-speed expert (thats 2 more than any bike I've ever owned), but is it possible that when the hub was 'converted', the internal
gering was left intact? If so, perhaps youre actually pushing much more than 2.52.

This is a really good point. If the conversion was nothing more than removing the shift cable and the hub is a Sturmey-Archer, then the hub is probably in '3rd' gear. A real easy way to test this is to raise the rear wheel and turn the cranks. Is the cog rotating in lock-step with the hub? If the cog is rotating slower than the hub then the unit is in 3rd gear which (for S-A hubs) means you are probably pushing something like a 3.35:1 ratio....ouch.

Jim

Chop
03-11-04, 11:30 AM
Is the cog rotating in lock-step with the hub?

Now I've got a real dumb question- What's a "cog"?

Schiek
03-11-04, 11:34 AM
Now I've got a real dumb question- What's a "cog"?

sprocket=cog

Chop
03-11-04, 11:36 AM
sprocket=cog

Thanks!