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Chainline Question(5 posts)

Chainline QuestionMatno
Apr 26, 2002 9:10 AM
I love my Schwinn SuperSport (circa 1991, 6 speed, full Shimano 600). It's my main ride and has been for the last 10 years. However, some replacements are necessary at this point, therefore upgrading seems like the logical step. I need new wheels. Both front and rear hop and there is no way to vertically true them. (I lived in Utah for most of the last 10 years and the rough roads there are hell on road rims - almost as bad as where I am now, the Bronx). My rear hub is okay, but the front hub is going and I think economically it's best to just get a new wheelset.

Also my bottom bracket bearings are going bad (still rideable, but squeaking) and my cranks, though in great shape, are BioPace Rings (Shimano 600) and kind of heavy.

I figure if I have to get new wheels and BB anyway, I might as well go 9 speed to get more gearing options and lose a little weight. (I know that's not staying retro, but I'm really more interested in a smooth ride on my comfortable old frame than keeping everything original).

As for chainline issues, That really doesn't make sense to me. To upgrade, I'll have to "cold set" my frame (stretch the rear apart about 4mm). Seems like if I then have a rear axle that is 130mm with a bottom bracket that is 68mm, the only issue I could possibly have with the chainline is my BB spindle length. Or not? I don't see how the frame could really affect chainline as long as it's straight.

How would I go about figuring out what BB spindle length I need? Is there a change in switching to a splined BB from a square taper one? Is there a standard to follow or does it depend on what rear hub I get?

re: Chainline Questiongtx
Apr 26, 2002 11:23 AM
most likely you could get the 9sp stuff to work with little or no hassle--depending on your frame and dropouts you might not even have to do a cold set. BB spindle length is determined by the cranks you are running--so there is one standrard length for the new Ultegra cranks (I think it's 109.5).

But here's what I'd do:

Contact this guy

and have him quote you a price a wheelset built with these freewheel hubs

then buy a previous generation Ultegra crankset on e-bay or somewhere and match it with a new UN72 bb (spindle length should be around 112 or 113). You'll save a bunch of money and maintain the look of your bike. You'll also drop some weight.

Have fun!
why change a good thing....Spirito
Apr 26, 2002 12:28 PM
it would be less of a parts nightmare than upgrading to just get a good seet of used wheels for it that will fit and maintain its style. such as

go to 9 speed then its time for a new crank, bottom bracket, and perhaps derailleurs and shifters. before you know it you will have spent $500 that if you want to sell will still only be worth $500 if that. keep it running as much as you can as is.

save you multi gear dreams for another bike and youll also appreciate it if you need to sell. trust me - we have all done this and regretted it mostly.

Cause it's no longer a good thing...Matno
Apr 26, 2002 9:41 PM

I could care less about the "style". For me, performance is paramount. Right now, about the only thing that is okay is riding along without changing gears. Not that the gears have gotten worse necessarily, but my expectations have gotten much higher. My mountain bike has quick precise 9-speed shifting that I would love to have on my road bike. Speaking of which, is it possible to combine mountain and road components? I'm thinking MTB rear cassette and derailleurs with road cranks and shifters. Is that doable or would that mess me up?
of course you can do itSpirito
Apr 27, 2002 7:03 AM
but pardon me as i thought you posted here as you wanted to keeep some of its easthetic.

if its a steel frame then yes you can stretch it to fit a wider rear hub. most say this is best left for someone with experience but it is not impossible and is common. you will need someone with a bit of experience in deciding what bottom bracket may be needed to keep the chain line on target. evry bike is a little different but here is a little reading

you can upgrade (rear wheel, cassette, shifters, crank, bb, derailleurs) but as i mentioned before if you plan on keeping the bike for a while sure go for it, but if you will hanker for something new soon you are sure drop a lot of coin for little return.

it may be better buying a used bike with all the gears and upgrades already there.

i notice you live in the bronx but im not too familiar with any bike stoes there but i do know that any manhattan store will take you for evey dollar you have even if its just to fit a new bottom bracket and crank and respace (stretch) your stays a little wider.