I remember the Travel Agent; that was a pretty cool aftermarket kludge but it seems like, ultimately, the world figured out that getting the right brake levers is cheap, and the feel is that much better. I´m thinking that the difference in terms of the amount of cable pulled for a canti/sidepull caliper (¨shortpull¨) versus a linear-pull/¨v¨-brake (¨longpull¨) is pretty small, compared to how much cable you´d need to move to actuate a coaster with any authority.
As I´d mentioned earlier, a smaller sprocket would help, and there is a good amount of variation between different models of coaster hubs, but think about how much you need to back-padal on a standard rear-mounted, foot-actuated coaster. Obviously, the pedals are at the end of the cranks, so that exaggerates the distance, but i´m talking in terms of how much chain is moving. To go from full-neutral (coasting) to full-brake (skidding) takes quite a few links´ worth of movement. I think it´s more realistic to hook up something non-bike to use as a lever, so you can really crank-up the total pull ratio and leverage crank-factor I think i recall seeing a buld here on RRB where they used hardware from a gate, but I´d be tempted to drill out and rig up a pr-24 or something like that, for both the BA factor and the fact that you could pick a fulcrum to really maximize the leverage....
