TRP makes a brake similar to the one adriano has posted:

http://www.trpbrakes.com/t925.html

Adriano's Oval brake looks nice and looks like it would work better than the TRP brake (more cable clearance).

That said, I've decided to go with no brake on this bike.

I think I can ride safely without a brake if I go to the 1/8 drivetrain discussed in another thread; if I keep my pedals properly adjusted; and, if I maintain situational awareness.

This discussion has helped me think through this decision.

Thanks to everyone.