ZenNMotion

I've never seen any, and if I did, I wouldn't trust them. But I'm guessing that your real question is, how can I use this old road bike frame for cross? If you have an older frame, set up for "normal reach" caliper brakes, you can use old-school centerpull brakes- these have lots of clearance for cross tires and plenty of stopping power. I have an old steel Schwinn commuter with Weinmann "Vaincoeur" centerpulls that I rescued off the neighbor's curb on garbage day that I can mount Michelin Muds (aggressive knobbys that measure 35mm) without a problem. I can also fit fenders in there as well- just barely with the muds, but easily with slightly lower profile 30c CX tires. Go find a bike shop that keeps old parts and I'm sure they will have a set of old weinmann's or universal's lying around- nobody specs or uses these anymore and it's too bad because they're still really good brakes, even if they're not pretty... But then, objectively, cantilevers with all the exposed cables are pretty odd looking also, especially on a high end CX frame with shaped tubing. Anyway, ask your LBS, buy a junker at Goodwill, check Ebay, or even pay a visit to the dump, it shouldn't be too hard to find some centerpulls. These may not work, however if you are trying to convert a road racing frame that uses short-reach caliper brakes as you may not be able to set the brake pads high enough to contact the rim properly, so you need to check that. But if not, just get an old frame that does- something like an old 70s-80's steel Raleigh Gran Prix or old Nishiki with centerpulls would make a perfectly useable cyclocross bike with lots of tire clearance. Those old roadies handle pretty nice on a cross course, too (I've done it with the Schwinn, it's fun!), although it might be a little heavy lifting over the barriers, it really wouldn't slow you down much over an expensive cross bike, especially in the C/B races your first couple of seasons. Spraypaint it neon pink, single ring with 1 bar-con shifter on a 6 speed freewheel and I guarantee you'd have more admirers than that Poser with the Carbon Ridley...

If you mean a brakeless bike, as in a track bike, then its something different. A real track fork does not have a drilled hole in the crown for a brake. And it's probably not possible or safe to drill it yourself. If you don't mind burning some paint, a frame builder could brake on canti bosses, shouldnt be too expensive. I've seen quotes for about 40 bucks per wheel. But if its a track frame you only need front cantis anyway for fixed gear riding, so just pick up a cheap used CX or hybrid fork and be done with it.