Originally Posted by
wilfried
I don't thing a double chain ring is an option, since we're talking mostly rolling hills, short stretches of steep climb followed by downhills or flats. I'd hate to have to get off the bike to switch chain rings on top of every hill.
I just fitted a front mech and changer to my Brompton when I added a double chainring. I was the cheapest Shimano mech I could find, the cage needed cutting to allow the chain to slip out of it when folding and the mounting bracket needed some work with mole wrenches and a Drehmel to make it fit. I did the same to my partner's Brompton too. This "bodge" has worked fine for over 1100km of touring.
I also
fitted 8 speed Nexus hubs into the bikes at the same time (modified hubs and spread rear forks). We built our own wheels which saved some money but the cost of the Nexus hubs, rims, rim tape and spokes was somewhat less than a new Brompton rear wheel and 6 sp BWR.