Problem frame - to drill or not to drill?

ne0sk
ne0sk Posts: 39
edited August 2014 in Road buying advice
Well, it seems the Cannondale R500 I purchased has a problem.........

The rear mech hanger bolts are threaded as is the thread in the hanger.

A Cannondale replacement purchased but the bolt size is now bigger (metric) so the holes in the frame are too small. I'm assuming the frame holes are unthreaded, if they are supposed to be then I have an even bigger problem!

2002 bike so ZERO chance of getting an original hanger.

Is drilling out the holes in the frame to accommodate the bigger hanger bolts an option? I have the right sized drill bits but am worried this could snowball into a complete disaster.

Am I best advised to leave alone and seek recourse from the seller (who may say "go away").

Risks of buying second hand..........