While finishing up AC's newest bike (one with a small frame to replace her old uncomfortable oversized single speed) I was taken by surprise when I ran into the same problem Dz did on his fixed/single speed project---that lame '80's under-frame rear brake was right in the way of the chain line, now that it sports only one gear. Unlike our previous bikes, she needs the rear brake to stay, since there will soon be a baby along for the ride, either on her back or in a cart being pulled behind; so it was necessary to somehow make it work. After contemplating grinding the brake arm and all sorts of other equally crazy ideas I came up with a solution: the biggest chainring and the stack of cogs from the disassembled cassette were still sitting around, and the only real advantage to keeping the drivetrain small is a tiny amount of clearance and weight savings; so if the current setup with a 34 tooth chainring and a 14 tooth cog = 2.4:1, (which is the desired ratio) the left over 46 tooth chainring needs a 19 tooth cog to achieve the same result. A bit of switcherooing, and presto! it clears! I will be posting some pictorial evidence of this triumph tomorrow...