pastorbobnlnh 

Fantastic work. I just don't understand how you shift the rear three sprockets. Isn't the Brompton just equipped with a chain tensioner and not a derailleur? Can you elaborate.

Have you run a gear calculator to see what your spread is and if there are any overlaps?

By the way, I'm a big fan of "the more gears the better." I've been running an 81 speed Cannondale for the past five years and I'm about to unveil a 54 speed Dahon.