Hello Vikars,
stumbled across your old thread and question today. I don't know, if somebody showed you a link to 'Stummelstolle'? Here it is:
http://kettenritzel.cc/2013/07/11/stumm ... -und-bunt/
I didn't know the name and the project up to this moment, too. Without diving too deep into it I'm pretty sure, that the name's derived from the German words 'Stummel', slang for clip-on handle-bars, and 'Stolle', for off-road-tyres ('Stollenreifen' in complete) ...
Btw, your bike's quite interesting, although I'm more into real Scramblers.
Kind regards, Bambi
'Find me kindness, find me beauty, find me truth' (Dreamtheater aus 'Learning to live')