i'm a little baffled at why Shimano doesn't publish basic specs for their current brake calipers, like reach.
i have an older bike, originally equipped with 27" wheels, now converted to 700C. the ancient (1984) Dia-Compe calipers are traditional single pivot, they work ok, and there was just enough adjustment available to permit me to use them with the slightly smaller 700C wheels. the pertinent spec is called reach, and it's the distance from the bolt attaching the caliper to the frame to the spot where the pad is fastened to the caliper. it's a range, e.g. 47mm-57mm.
newer bikes typically have shorter reaches. this isn't something i paid much attention to until i decided that perhaps i wanted to convert from the old single pivot Dia-Compe calipers to a newer dual pivot. i started going through current Shimano products, and found it fairly difficult to establish what ranges their calipers covered. Eventually it became clear that none of the higher end Shimano calipers will fit properly on my 26 year old bike.
There is still some hope, however. The Shimano R600 dual-pivot calipers from the early 90s are still lurking out there, and will fit. And a Taiwanese firm, Tektro, is making new calipers in a variety of sizes and configurations; reviews are scarce but the small number I've found are positive. Now to decide which way I want to go...
