Well, I'm thinking of something that I can fly with, and then bike around say, Portland. I might just be making things up, and might bounce this over to the singlespeed forum, but here we go...
I'd want to be able to move this thing around loaded and unloaded, and yet still have no derailleurs. Which means two dramatically different cogs. Which means horizontal dropouts. But, excluding the Quickbeam dropouts, I'm don't know if there's a good way to get brakes on something like that, since the wheel position would be different for each cog. If I was moving around with a trailer (most likely my Bobyak) I would certainly want a rear brake of some kind.
Does a coaster brake/fixed hub exist? Would a coaster brake work just as well on a 20" wheel? Don't see why it wouldn't...
Adventures, adventures....
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Villin custom touring | Raleigh XXIX | Medici Pro Pista | 1978 Schwinn Stingray