Hi, Blackstridaaustria, thank you very much your quick answer! well, I took some pictures of my Strida 2(?) to confirm I am correct but still did not discover the path to post it, so in meanwhile I found that one of the two Mk1s is model nº13991 while the other lost it’s identifying sticker, although it may surely have the same “age”; the other I name STRIDA 2 has a metal sticker strip showing nº 000806; it is metalic silver with a grey plastic cranck “cassette”, beltwheel (pulley) and upper join halves with black SRIDA logo; whells are also grey, and i found that, as Mk1, the handle barT is also made of steel tube; for the first time the British Flag gave way to a strida.com logo… already made in china?
With the broken bike cassette I tried to replicate the more complex function system used with the Plastic Mk2 cassette, but (may be because I do not have enough precision tools) altough it seems to be firmly fixed to the tube frame, when I pedal as I would when climbing, i can clearly see the cassette moving some 10 or 15 mm from each side of the verical position,so the rear pulley flange is doomed, if I do not get a solution… So, I have been sketching (CAD) two similar solutions, for two very different cassettes (bottom bracket castings, easier calling it cassettes, isn’t it?): a rectangular welded aluminium (minimum 6mm thick) “fin”, crossing vertically the tubular frame and entering as much as possible inside the cassette from where a male rod gets out enough to get the nut that allows correcting the belt tension; the two horizontal bolts that cross the plastic cassette to fix it after correct belt tension, will have to be replicated in the older metal cast cassettes; In the plastic cassettes the “bee nest” reinforcements have to be “filled” to accommodate the new fin, while in the hallow metal ones some transversal reinforcements, two or three will have to be done to help strength… what do you think about it? these parts could be eventually laser cut, in all a way to put these vintage Stridas out there… if possible, I could send you my Stridas images and the CAD drawings (they are almost done), that you could post or insert in my reply post…