Yeah, who knows whether concave rims offered any real advantage, or whether it was a fad like Univega's cool looking bi-axial oval frames.

The tricky bit is finding brake pads that fit properly.

I started out with Kool Stop Eagle 2 pads on this particular bike. Good pads, easy to toe-in (the plow tip is self aligning), but tricky to align perfectly to clear the tire while maximizing contact. The pads were just a bit wider than I'd like for the Araya PX-45 rims. And too thick to clear the fork enough to easily drop the wheel with slightly oversized tires.

So I switched the front set to Jagwire Mountain Sport 70mm pads for cantilever brakes. Perfect. Thinner, to fit the rim perfectly, snugged into the concave surface. Curved to match the rim. Longer than the Kool Stops. Overall more effective brakes than Kool Stops for this particular rim. I kept the Kool Stops on the rear wheel.