Dual pivot caliper brakes are an improvement on single pivot caliper brakes, the kind of caliper brake that was fitted to bikes in the 1980s and earlier. The two pivot points provide more stopping power than one.
Dual pivot calipers provide an excellent combination of reliability and performance. They are very easy to set up and they require minimal maintenance once fitted.
Since they are standard on road bikes, they are compatible with standard drop bar brake levers, as well as flat bar levers designed for cantilever brakes.
Where a frame has too much space between the brake bridge and the wheel, and a deep drop brake can’t be found, drop bolts can be used. They’re strips of aluminium, spaced with a slim tube, which act as extensions of the frame to lower the brake hole. Pictures of home made drop bolts can be seen here (scroll down slightly). Flat strips are necessary on the fork where a tube can be inserted in the steerer, from the bottom. This is stronger and simpler.