Chain Line Question

[Dosninerguy]

How do i know the proper spacing for the bottom bracket to have the proper chain line for a mountain bike triple crank and nine speed cassette?

Thanks, i hope some one can give the learning on this one.

[Bill]

Hi Dos,
Try watching this and see if it helps....
http://bikeride.com/calculate-chain-length/

If this is not it come back and we can still help ya out.

[cyclerUK]

Sheldon Brown "chainline":-
http://www.sheldonbrown.com/gloss_ch.html#chainline

The chainset can be moved in or out a bit with limitations.
You need to check the front derailleur chainline "dimension".
(If Shimano, then see their appropriate tech' document.)
If the chainrings are to far out then the FD won't reach the outer ring.

If the bottom bracket is to short then the inner ring may catch the chainstay.

If buying a new chainset then there may be a recommended BB dimension with it.
Another possible problem, if the chainset is too near the frame, is the chain will catch the outer ring with the chain on the middle ring and smallest sprocket.

[Bill]

Again I learn something new lol . Thanks cycler. Think I better brush up on the terminology, very very interesting on the dimensions, cool.

[KDC1956]

Very good cyclerUK you hit the nail right on the head. I could not have said it any better my self. Books are so much help at times. :-)