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Crossover Problems(6 posts)

Crossover Problemsklbeans
May 7, 2002 5:25 AM
I just recently bought a 50 cm Cannondale R2000 SI. After riding it for a while, I notice that the chain will rub slightly when I'm in the 39/14 combo - the bike is equiped with ultegra, gearing 53/39, 12/23. That would be the 3rd cog in. I find this slightly annoying as there are times when I could use this gear for a short time ie. going down a hill, etc... and would rather not have to switch up to the larger chainring and reposition my rear derailleur only to have to switch back momentarily.

I know it's not good practice to crossover the chain, although, this gear combination is only 2 cogs off centre.

I wrote Cannondale an email and they replied it's due to the short chainstays. Basically, don't ride that gear.

A friend of mine has the same gearing configurations and groupo on a Colnago and has no problem riding this gear.

Any comments would be greatly appreciated.
Fairly common problem.Spoke Wrench
May 7, 2002 7:14 AM
We had a really fun discussion regarding this about a month or so ago. I'm assuming the chain is rubbing on the big chain ring, not the derailleur cage. In a nutshell, the quick and dirty solution is to put a 2mm spacer under the right side of the bottom bracket. That's what I've done with my Klein. If you want to be a little more elegant, you can use an XTR BB with a 112.5mm spindle.
Yup...Mike Prince
May 7, 2002 7:26 AM
fun it was. You should be able to get the spacer from your LBS. Make sure you readjust your FD limit screws after doing this or you may get an unpleasant surprise the first time you try to get into the 39 (chain drop).

Mike
Fairly common problem.klbeans
May 7, 2002 9:33 AM
What type of spacer would I use. I'm assuming this spacer is originally manufactured for some other application than to act as a spacer to push the bb over.
Fairly common spacerKerry
May 7, 2002 4:38 PM
Your shop should have spacers. If all else fails, a Sturmey Archer hub spacer works. Assuming an English (1.370 diameter) BB, then you need a spacer of this size.
Actually its called a "fixed cup shim."Spoke Wrench
May 8, 2002 5:02 AM
If your local bike shop doesn't have one, tell them the QBP part number is TL3022.