Since Eden Fowler got in touch with his excellent write up and photos of his 1990 Brompton M3R, he has now done what he said and converted it to to a 6 speed bike. So I guess now it is 1990 Brompton M6R! Is there no end to this man’s talents? If you have an older Brompton 3 speed bike you may fancy doing your own Brompton 3 to 6 speed conversion. Read on, this is great…
I thought I’d add a PS to my last offering when I was seeking a more recent rear frame in order to enjoy the six gears that fitting the derailleur permits. Well, to cut a long story short, & after sounding out a lot of sources of Brompton lore, I decided to go it alone & modify my 1990 rear frame to take a Brompton derailleur.
The essential piece is not available from Brompton so I put a 5mm thread through the centre of a short piece of 14mm diameter mild steel bar and then filed it to the tube profile at one end and a hexagon to take the “Chain pusher wing plate” at the other end. I took into account the very modest loading on the chain pusher, & chose silver-soldering as the best means of fixing the piece. It can be done with a simple camping gaz torch and puts much less heat into the job than brazing. A washer also had to be silver-soldered to the original cable guide to act as cable stop.
Recent Comments