Ok so the link between the pedal and the spring will be a length of wire rope. For this to work I also need something to fasten the wire to the pedal arm, to the spring assembly and something to stop everything coming undone.
My plan is to have two strands of rope coming from the spring assembly, over the pulleys, both passing through an eye bolt on the pedal arm, doubling back over and then being fastened.
To get all the parts I need I have ordered from a place called 'tecni-cable'. How to fasten the wire rope is an important question as you can't simply 'tie a knot in it' like you can with string. The rope needs to be able to support a load of 90kg (on the safe side) from my calcs.
From the tecni-cable site I order 3m of 2mm diameter stainless steel 7x19 wire rope. I think the '7x19' refers to how the strands of steel that make up the cable are arranged. Apparently 7x19 is supposed to be quite flexible.
To secure the rope to the pedal arm I order a couple of M6 eye bolts. To secure it to the spring assembly I order a couple of M8 eye nuts (not bolts). These must be M8 because I have already brought the M8 threaded rod to use. To tie/fix the rope I order four 'duplex wire rope grips'. I hope these will work: I spent ages looking into something called 'swageless terminals' to use instead, but decided that the fixings themselves are too large to be used inside the pedal box, which will be quite tight on space.
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