I ride a lovely freak of a bike. A '78 Motobecane singlespead with moustache bars and cyclocross tires. It's been clearcoated over the original paint and I love it. I use it for everything (commuting, road, light trails). I'm getting ready to build a new wheelset and am trying to figure out how to adapt disc brakes front and rear. Id' prefer to still use the comfy hi-rake original fork. Any ideas?

I would doubt that the original fork would be strong enough for disk brakes. You should look for a disk fork or maybe a tandem fork. Something made for the braking stress to come from the center of the wheel not the rim. There are several companies that make 700c disk forks due to thier use in CX racing. Might cost you about $100 or so.

Who makes a rear brake adapter to mount the caliper on the frame?

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