Custom Drop Bolt for Front Brake Mount
I recently bought an old Nishiki 62cm frame from The Hub Community Bike Shop to ride as a fixed-gear bike. It was built for 27-inch wheels, but I want to use 700c for all my bikes. That meant I needed a long reach caliper brake to reach the extra 4mm down to the 700c rim. But this frame also has cantiliver brake bosses, and long reach brakes interfere with those.
The solution was to mount my existing caliper brake to a homemade "drop bolt", as described by Sheldon Brown. It's been working well for about a month.
In the photo below you can see how some extra washers push the caliber brake forward just enough to clear the bosses.
Surprisingly, my junk bin had a pair of brass rectangles that were already the perfect dimensions and were already drilled with two holes at the correct spacing. All I needed to do was enlarge the holes to accept 6mm bolts, get a long stainless steel M6 bolt, washer, and lock nut at the hardware store, and cut a section of lamp nipple to use as a spacer on the lower bolt.
The brass bits came from an antique printer's cabinet that I got off of Craigslist a few years ago. They were used as stops for whatever was placed on the sloping table top. I took them off and saved them when I refinished the cabinet. I'm glad I did.