Fascinating stuff! Just relooked at this stream again and the latest detail on using Neoprene, also brake lining rivitted . Great pics! I have found the paper pulley company good but I was still getting too much slip. I have now made an Aluminum ring ( replacing the whole paperpulley material) with correct hole centres but 5/16, 8 mm smaller diameter than required to which is bonded an 8mm brake ling material. The choice of material is critical. A much older foreman at Industrial Brakes in UK advised it should be a "cotton fibre " brake lining. I have fitted it and it so far (200 miles) it is working very well. I have also made up the same aluminium ring and had a polypropylene 8mm bonded to it. I have not tried it yet. Note Cartercar 1911 advertising 50% gradient no problem. See pic of 1914 Brittania sole survivor.
My flywheel is steel! All others seem to be aluminium; is this a problem? If so why? Look forwards to chat!