Originally Posted by
bromptonS8
1) make the rear triangle pivot axle narrower than the bottom bracket so the chainring can go outside the rear triangle struts (ala Brompton) . . . . My guess is that the use of aluminum precludes Option 1 for the Dahon.
On second thought, the Birdy rear "triangle" is made from aluminum and solves this problem fairly well (albeit more expensively). I looked at the patent and cannot understand why a Birdy-like pivoting structure wouldn't work for the Curl, which would allow larger chainrings.