Touring with Bromptons in 2007.
Both of our Bromptons are six speed models. Damae's (the yellow one) is three years old whilst mine (the blue one) is still in its first year of use. The main difference is that mine was a cheaper bike than Damae's. Damae has a rear rack and originally had a Brompton/AXA dynamo lighting set. The other difference is in the size of the chainwheels. After having ridden Damae's bike with a 50 tooth chainwheel I ordered mine with a 44 tooth chainwheel. Unfortunately, I had to argue with the salesman at the shop I bought it at as he thought that I did not understand what I was doing. This was very annoying.
Even Damae (who likes to pedal a bit more slowly than me) never uses high third gear and only rarely low third, so those two gears are as good as wasted. With a 44 tooth chainwheel the spread of gears is much better, high third gear is good for cruising up to thirty-five kilometers per hour, and low first is good for fast town starts and reasonable gradients.
The main problem we have with the bikes as regards gearing, is the lack of a true low range. Our touring bikes have a nineteen inch low gear, which lets us crawl uphill at between four and six kilometres per hour. We are currently looking at front derailleurs, the Mountain Drive and a Rolhoff conversion as possible solutions. As for other niggles, Damae could do with a higher handlebar stem and we have our doubts about the strength of the Brompton rear wheel, both having broken rear spokes (in Damae's case three of them in the first year).
A useful addition to both bikes was bar ends which give some variety in hand position. The big problem with bar ends on a Brompton is clearance when folding so you can only have short bar ends. Not being sure which would and would not fit, I went for the cheapest ones I could find. I shortened them so that the bikes would still fold before refitting the end plugs and adding foam handlebar coverings. Damae has a rear rack on her Brompton which is lucky as she needed more height from the bar ends. Thus her bar ends stick up more than mine. My Brompton does not have a rear rack so my bar ends are almost horizontal. You can see the difference in angle in the photo above.
I fitted a set of SPD pedals to my Brompton as I discovered I rarely used the folding pedal and the other pedal on the Brompton is not particularly good quality. With my cycling sandals I have no problems clearing the rolling wheels on the rear forks and with my cycling boots I occasionally scrape the inside against the outside of the wheels. Damae has had a different problem in that she hits the wheels with her calves, so adding SPD pedals to her bike did not create any additional clearance problems.