Many old wide-profile cantilever brakes from companies like Dia Compe and Polygon came with doubled-ended straddle cables. These cables make brake setup a bit easier, since it reduces the three confusing variables (pad extension, straddle length and straddle height) down to two. The downside of these cables is that the fixed length eliminates one major adjustment technique to modify the power vs. clearance ratio. Plus when it’s time to replace one? Your local shop doesn’t have them in stock. And if they do? It’s usually not the right length, as they vary from 300-380 mm long.
One solution we’ve found to overcome both of these problems is to use an adjustable cable end. When our local bike shop was out of double-ended straddle cables for our retro ride a few years back, we dug around in their small parts bins and came out with these. We bought out their supply in both sizes, but your local shop should be able to order you some.
With these, you can make your own double-ended straddle cable by simply threading the end of a common single-ended straddle cable into the hole and then tightening the Phillips head screw down (tightly, these are your brakes after all) to secure it in place to make a cable of the desired length.
They come in two sizes, but either converts a normal mountain bike brake cable or single-end straddle cable into a double-ended one. The larger one fits better in some brakes, but the smaller one will work in almost any slot.
With this type of cable end, you can adjust the length of the straddle cable and tweak until your retro brakes until they are full dialed.
Adjustable Cable End (is there an official name for them?)
Price: Two bucks each at our LBS
For more info: Your LBS (bring a picture of it in case they give you a blank stare)