Chainring Compatibility Question
 

I have a late 90's issue Campy Chorus 9 equipped bike. The crank is set up with 51/39 chainrings. Is it possible to put some slightly smaller rings (like 49/37) on without switching out for a compact? If so, what sizes will work?

Thanks in advance.

Here's how you measure the bolt circle diameter. Measure yours and then go nuts with someone like BikeMan (they have a pretty good selection).

Thanks. Looks like I can go down to a 38. If I couple that with a 13/26, I'll be in better hill shape than I am now (12/23).