Keeping a classic bike running is often a challenge, especially when it comes to fitting brakes. There have been two significant changes to brake technology since the mid 1980s relevant to classic frames. First, wheel sizes have changed, from 27 inches (now designated ERTRO 630) to ERTRO 622. Second, the mounting has changed, from an external nut to an internal allen fitting.
An old-style brake, made for 27-inch wheels on a frame now fitted with ERTRO 622 wheels, may not reach. There are several options. This page offers a few solutions.
First, if you are extremely lucky (don't count on it) with a frame made for road racing, that is, with close clearances and no provision for mud guards, old-style brake calipers might just reach the newer smaller-diameter rims. See below for an example.
If you are not so lucky, you have some options.
Option 1: rebuild your wheels on rims with tall side faces. ALEXRIMS AT 400 PRO will fit Campagnolo Nuovo Record calipers, running 622 tires. (But, measure the drops before you buy!) See below.
Option 2: rebuild your brake calipers using a drop bolt. Campagnolo issued these for a few years. It provides an offset of 8 mm, extactly the difference between ERTRO 630 and 622. See below.
Option 3. If 8 mm drops are not sufficient, then construct drop mounts which offset the caliper assembly by the required amount. The brake mount featured below was milled to customer specification from aluminum.
Option 3B. If 8 mm drops are not sufficient, and you have extremely short-reach brakes to fit, such as Campag Deltas, you may require a more elaborate mounting piece than a simple drop bolt. See below.
Above: the front mount fits into the steerer from underneath and is fixed with a standard metric bolt. The rear mount clamps onto the brake bridge on both sides, providing a rigid mount for the brake body, illustrated below.
A machine shop milled the aluminium mounts to customer specification. The parts were expensive; I would not want to do this for all my classic bikes, however, Deltas are extremely short-reach brakes and a simpler drop bolt would not have worked. Campagnolo still deliver new pads for Deltas; Deltas tend to squeal if the pads are not kept fresh and pliant.
Option 4: Several manufacturers, such as Shimano, Acor, Starry, and Alhonga, produce modern dual pivot brakes with long-reach calipers for old-style frames. Below: Alhonga model 714 on a 1984 Keyhole. Specs: 51-69mm drop, nut fitting, price 24 GBP, pair, incl post and packing, from St. John Street Cycles, email: email@example.com
Farther below, the Starry model, drop range 60 to 85 mm, external nut fixture.
Be advised that this may not be accepted at vintage events, such as l'Eroica, but is perfectly suited for a daily rider.
These options should get your 1940s-to-1980s bike back on the road.
Last but not least dept.: be advised that 1930s frames with curly stays and Resilion brakes are not a good fit, as the curly stays have a steeply sloped angle for which the Resilion brake pad assembly was not designed. You will have trouble getting the pads aligned correctly. (Resilion brakes work as intended with straight-stays Hetchins.)