Okay so the plot thickens. Doing an Image search for Brompton I found this on a Japanese site...
Sweet huh?
But look: It's got
no tensioner. My Kanji is non-existant so I can't be sure—but it looks for all the world like a fixie to me. So I have an idea. When 'riding' the chain tension is not really going to be an issue - the flex in the suspension rubber bush is only tiny so theoretically it should be fine. So then the problem is folding.
I have in mind now an idea (if the chain gets slacker when you fold) that you could use some sort of tensioner to keep the chain on
when folded only and then disengage it when in use. If that were possible (seems likely to me) then apart from a bit more faffing when folding it could be
the solution.
Can anyone confirm once and for all about whether the chain gets slacker or tighter when you fold the wheel under???
Full page of this bike (and other nice Brommies)