Bike Build - Bianchi Via Nirone rear brake fitting

espencer86 Posts: 15
edited September 2012 in Workshop
I picked up a 'new' frame today - a Bianchi Via Nirone with the carbon rear and am currently building it up with the groupset of my destroyed CAAD9 Tiagra.

I have encountered a problem with fitting the rear brake. The bolt on the brake is not long enough as the frame is so chunky where the brake attaches. Am I right in thinking I just need to buy a longer (27mm) sunken nut or do I need to buy a new rear brake?

Thanks in advance... sure I will have a few more questions over the course of tomorrow!