Dia Compe BRS 100 - Help

I recently bought some Dia Compe BRS 100 brakes, due to the massively techincal reason that they're red. Unfortunately the screw in the back doesn't fit in the frame.

My flatmate suggested getting the back of the frame insert drilled and I've been quoted a price from Hackney Central Bikes and Look Mum No Hand! But Micycle said they could but wouldn't because it would weaken the frame too much.

Does anyone have any opinions on this? Sorry if this is a lame question but I've got little idea about these things so help would be appreciated.

Do you mean the allen nut that threads onto the bolt on the back of the brake calliper doesn't fit through the hole in the forks?

If so, just consider drilling it yourself. I'm not an engineer or mechanic, and I recently drilled out the back of my forks to accommodate a Tektro R536 front brake. My frame only cost a quid off eBay so I wasn't too bothered if I screwed the whole thing up, but it went pretty well and the calliper now fits perfectly.

I say 'pretty well' because I knackered one drill bit and a second one is looking a little less sharp, but the forks are pretty thick steel. Make sure you use a mains-powered drill (cordless won't cut it - literally!), a decent HSS drill bit (usually 8mm, but check by holding it up to the allen nut), regularly douse the hole with oil or other appropriate lube (not K-Y), and have a steady hand, as a twisted hole will lessen any stopping power from the calliper.

What frame is it? What's the material? How sturdy are the forks?

I drilled my forks myself very easily with the correct size metal bit in order to use a recessed allen bolt.

Its simple but please don't take that as a recommendation to screw up your forks if you're not 100% with drills and tools.

Cheers for the advice. I've covered myself in KY jelly and have my drill in hand.

Actually, I chickened out and have left it with someone else to do it for a small fee whilst I'm at work.

I've got no idea what the frame or forks are either, but they're definitely steel. I'll post pics once it's done so maybe you can guess.