Chain line

[convert]

Ok I made the switch from a mountain bike to a performance hybrid and got a Specialize Sirrus, I put cyclocross tires on it and it goes just about anywhere. Now the problem is the chain line, I can't use the middle front and largest back, my chain wants to derail to the granny gear, I can barly use middle front 2nd largest back losts of noise, the shop tell me, well that they can't fix it. Specialize tells me to try a shram chain as they are more flexible. I am told that a shorter B.B. will not work as the front derailler will not be compatible and bottom out. Anybody have an idea what I can do.
Thanks

 

[daveornee]

Originally posted by convert
Ok I made the switch from a mountain bike to a performance hybrid and got a Specialize Sirrus, I put cyclocross tires on it and it goes just about anywhere. Now the problem is the chain line, I can't use the middle front and largest back, my chain wants to derail to the granny gear, I can barly use middle front 2nd largest back losts of noise, the shop tell me, well that they can't fix it. Specialize tells me to try a shram chain as they are more flexible. I am told that a shorter B.B. will not work as the front derailler will not be compatible and bottom out. Anybody have an idea what I can do.
Thanks

Side flex of the chain may help.
Where are you starting from in the chain line?

See the Park Tool site listed below:

<http://www.parktool.com/repair_help/clg2.shtml>

If your middle chain ring aligns with your middle cog, all is about as good as you can get with your chain line.
You may be able to attain the same gear ratios with other combinations that your set up will work with, but I would pursue your challenge and keep after the dealer and Specialized.

For some very interesting information on side to side flexibility of chains see the article by Damon Rinard listed below:

<http://www.damonrinard.com/chain_stiffness.htm>

Based on those results, KMC Super Shuttle would give you the most side to side flexibility. However, shifting is also effected.
You might also want to check your dropout alignment and the run out on your middle chain ring.

 

[convert]

Originally posted by daveornee
Side flex of the chain may help.
Where are you starting from in the chain line?

See the Park Tool site listed below:

<http://www.parktool.com/repair_help/clg2.shtml>

If your middle chain ring aligns with your middle cog, all is about as good as you can get with your chain line.
You may be able to attain the same gear ratios with other combinations that your set up will work with, but I would pursue your challenge and keep after the dealer and Specialized.

For some very interesting information on side to side flexibility of chains see the article by Damon Rinard listed below:

<http://www.damonrinard.com/chain_stiffness.htm>

Based on those results, KMC Super Shuttle would give you the most side to side flexibility. However, shifting is also effected.
You might also want to check your dropout alignment and the run out on your middle chain ring.

Thanks for the reply
I will check out what you have sugested