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Discussion Starter · #1 ·
I just built up an 04 Litespeed Classic by switching over the parts from my 02 Cannondale R2000. The Cannondale chainline and shifting functioned perfectly, but now the Litespeed has chain rub on inside of the big ring (50) when I'm in the 34x12 gear and also on the next gear up, 34x13. I'm running an FSA Carbon Pro Elite Compact Crankset with an Ultegra 113mm Octalink bottom bracket.

I took it into my local shop, and they adjusted the deraileurs and added .6 millimeter spacers between the crank chainrings, which helped but didn't solve the problem.
They did not want to add 1mm spacers between the rings because of concerns about the chain dropping between the rings during shifts.

They recommended possibly buying a 118.5mm bottom bracket, which is for a triple crankset, but that doesn't sound right to me.
Does anyone have any ideas?
I'm all out of them.
I'm still not sure why my setup worked on the Cannondale and now doesn't work on the Litespeed.
 

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Does the lightspeed have shorter chainstays?
Are the chainrings closer to the center of the bike? IIRC, the spec for ISIS doubles is 45mm from the centerline of the bike to the center of the chainrings.
A triple BB would really mess up your chainline for the large cogs. If you have to space it out, a spacer on the BB would be better.
 

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Discussion Starter · #3 ·
ericm979 said:
Does the lightspeed have shorter chainstays?
Are the chainrings closer to the center of the bike? IIRC, the spec for ISIS doubles is 45mm from the centerline of the bike to the center of the chainrings.
A triple BB would really mess up your chainline for the large cogs. If you have to space it out, a spacer on the BB would be better.
I'm not sure about the chainstay length difference. I'll have to measure.
I didn't know they made BB spacers! I'll definitely give that a try. A 1mm spacer
might do the trick.
Your right, going to a triple BB would just create issues going the other way by
pushing things too far out.
Thank you very much for your advice.
 

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your shop screwed up...

Check the chainline, the big ring should be 47-48mm from the center of the seat tube to the tip of a tooth on the big ring. Measure from the side of the tube and add 1/2 the diameter of the seat tube. Mostly likely 6mm was way too much spacer to add. Now you shouldn't use the big ring and the largest two cogs, since the crank has been moved to the right more than the spacing of one cog. Even the little ring and and largest cog is probably a bit extreme.

It's perfectly normal for a compact to rub in the 12 and usually it rubs in the 13, according to most users.
 

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That was .6mm, not 6mm. I think spaceing the rings slightly farther apart is a good partial solution as is a BB spacer. The shop was right not to space the rings too far apart for fear of dropping a chain between the rings. Rubbing seems to be a fact of life for compact cranks and certain frames. One of the reasons I'm not a compact crank fan. Compact cranks are not new. They've been tried before and found to be wanting. To me it's a marketing ploy. Manufacturers always have to offer something "new" and "improved" to keep sales up. Not saying they can't work and aren't a reasonable solution in a few applications but usually they only work well when the whole system, including the frame, has been designed around compact drivetrain geometry.
 

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To solve the problem

Please check my thread, as i had the same problem b4. and i got it solved just yesturday, thanks to the guys who gave me the suggestion.

'Compact crank - anyone had this problem before?'

Hope it helps solve yours
 
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