I was taken by the idea of using twistgrips as per Steve's (Parry?) bike featured in the article in Velovision 2009.
I've bought a pair of SA twistgrips (not quite the same to look at as those in the article 'Building on the Brompton') and the right one works fine with the Sachs hub gear but I cannot see for the life of me how to make the other one work the Brompton rear derailleur.
The problem is the inner cable connection. On the Brommie the cable inner threads, against the tension of a couple of springs, from the derailleur to the shift lever, where the end is secured by a clamping screw. On the SA twistgrip the cable threads the other way because the stop on the end of the cable has to fit inside the twistgrip.
I've tried fitting a screw block at the end of the cable where it passes through the dogleg piece of the operating mechanism and can get a shift one way, but without sufficient tension for the derailleur to return. I can't reverse the SA inner cable because the lug is a wider diameter than that on the Brommy inner cable and so it won't slide down the tube with the inner spring in and, even if I was to file it down, how would I secure it inside the twistgrip?
Anybody got any ideas on how to resolve this, please?
