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determining chain line
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preamble: i ride a cervelo p2 (not p2k) with 650 wheels. rings are 53/42 (53/39 if course is hilly). crankarm length 175mm. 8 speed ultegra drivetrain. cassette is (presently) 11-21 (12-23 if course is hilly). wipperman nickel chain.

question: i know not to expect to use the most extreme gear or 2 on either chainring, but how do i make sure my chainline is properly adjusted? the chainstays a pretty short on this bike and the chain starts going on an angle pretty quick when shifting through the gears. it shifts crisp and easy right now, but i want to ensure i'm not putting any excessive strain on the chain (don't want to break it).

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Re: determining chain line [sydnrusty] [ In reply to ]
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There is no adjustment that I am aware. If you have the right sized Bottom Bracket and your bike has not crashed, you should be fine.
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Re: determining chain line [sydnrusty] [ In reply to ]
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I use an aluminum meter stick and hold it against the inside of the large chainring. It should line up with the middle of the cassette (for 8sp, between the 2 middle cogs). If it doesn't the solution depends on the type of BB you have. Most cassette type BB's are not adjustable other than by putting shims between the BB shell and the cassette. AC, Phil and others are very adjustable.

With 8 speed I wouldn't worry about it unless it's way off. With 10 speed it becomes much more critical since the margin of error is reduced.
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Re: determining chain line [sydnrusty] [ In reply to ]
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http://www.sheldonbrown.com/chainline/index.html

I've got a tandem with a huge chain line problem. When in the middle chainring/smaller sprockets, the chain rubs the big chainring. It has 160mm rear spacing. White Industries said that it is impossible to re-space their rear hub. Moving the crankset/front derailer out would increase an already big q-factor. My solution: I choose my gears carefully. I use the big chainring a lot and use the middle and small rings for only the very biggest sprockets.
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