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Join Date: Oct 2016
Location: Cambridge UK
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Bikes: 1903 24 spd Sunbeam, 1927 Humber, 3 1930 Raleighs, 2 1940s Sunbeams, 2 1940s Raleighs, Rudge, 1950s Robin Hood, 1958 Claud Butler, 2 1973 Colnago Supers, Eddie Merckx, 2 1980 Holdsworth, EG Bates funny TT bike, another 6 or so 1990s bikes
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Stepping out
You can get brake pads that step down to accommodate. modern rims on older frames. Also as mentioned above you can purchase or fabricate an extension that lowers the entire caliper so the normal pads can reach the lower 700c braking surface.
Elongating the slot on existing calipers is living dangerously as Al work hardens and thus becomes brittle once it's been filed..