Originally Posted by
Novasteve74
...had plans to run a Girvin Rock Ring bashguard as a chainwatcher, but apparently they used a smaller 7mm bolt diameter. The new 10mm chainring bolts fit the cranks/chainring, but not the Rock Ring
.... I guess I'll have to do some drilling, but I'm undecided as of yet. I wanted to run the Rock Ring since I'm running a 48t up front which requires the ring to be on the outer ring position of the crank spider to clear the chainstays. The Girvin was perfect because it didn't replace a ring, but rather overlayed the ring in the outer position, and it could take the 48t ring (which is pretty hard to find). ...
I'd drill them to 10mm and be done with it--it seems like its the system that makes the most sense to you. Will be very easy to do on a drill press (or, if very careful, using a vise or c-clamped to a stable table). If you;'re worried about it, I'm sure your LBS would be happy to do it.