[oily666]

I've almost completed a new bike. Some new stuff, some close outs and some stuff I already had. All Campy Centaur with Chorus Ergo 10 shifters. 2007 Centaur Carbon Compact called for Centaur 111 BBB which I installed. It's the one with double bearing races on the drive side. However, when I'm on the 50 tooth in front and the 12 in back, the chain runs so far to the right it barely misses the crank arm. When it's on the 34 inner ring, the chain drags against the inner side of the big ring once I upshift past the fifth sprocket in the rear. The wheels are perfect and all the required components are in place but I still have this situation. Please check out the photos and let me know if you've ever seen this before.

Thanks

A word to the wise ain't necessary -- it's the stupid ones that need the advice. -- Bill Cosby

 

[robert_shawn]

It's kind of hard to tell from the photos, however if I were to hazard a guess it would be that you need to adjust the spacing of the crank to the bb. I have not dealt with newer campy stuff, but shimano outboard BB's usally come with spacers to adjust chain line. A fairly good rule of thumb is that a line that runs midway between the two front chain rings in the same plane as the chain rings should run through the middle of the cassete which should also be in the same plane as the chain rings. If you don't have a spacer your LBS should probably have one.

Shawn

 

[DY123]

Look at the Campy instructions. The chain line is supposed to be 43.5 mm. Check that against your bike and you'll have a better idea of if there is a problem and if so what is causing it.

 

[C-40]

about 43.5...

If you can figure out a good way to identify that point in space between the two chainrings, let me know. It's a whole lot easier to meaure to the tip of a tooth on the big ring. That dimension should be in the 47-48mm range. It's simplest to measure from the side of the seat tube and then add 1/2 the seat tube diameter.

I've never understood why all brands continue to list the silly 43.5mm dimension. It should be done that same way as the middle ring on a triple, only to the big ring.

 

[oily666]

You're right C-40. It looks good on a line drawing but a real meaurement will require more than a metal scale. I've built and modified bikes for over 30 years and I've never seen something so fubar result from using the exact components specified by the manufacturer.

 

[russotto]

If you can figure out a good way to identify that point in space between the two chainrings, let me know.

Measure to the inside of the big ring. Measure to the outside of the little ring. Take an average.

 

[C-40]

sure...

Measure to the inside of the big ring. Measure to the outside of the little ring. Take an average.

Since I worked in machining and precision measurement for a lot of years, this is obvious, but still seems like a silly way to dimension something, since it increases the error.

 

[DY123]

Did you measure the chain line?

 

[oily666]

Pro wrench found the problem although it wasn't visible to the naked eye. Bent derailleur hangar.