c5alive previously supplied replacement chains for c5's, but stopped because there didn't seem to be any demand for them.
I've experimented on a recently purchased C5 - best described as "in need of TLC". I fitted it with a cheap Halfords bike chain .
It's an improvement on the seized Sinclair chain , but will still slip slightly when put under pressure going uphill.
For normal use, it provides a cheap alternative but isn't really up to the job.
Next up, a heavy duty (more expensive) bike chain....if this isn't successful I will return to the previous supplier and see what the present costs are for a proper spec chain. This may lead to C5alive stocking replacement chains again.