Thanks gents,
24 teeth on the big cog. It had a 1/8th chain on it - and I had a new one in stock. And yep, I think that's the main issue.
But then the new cheapie crankset is 1/8. A 3/32 chain would mean different cranks, no?
I'll check numbers.
It all lined up and the travel was plenty.
I haven't give up, but I think for now I'll ride it for a while to see if it needs the effort. I do like the simpler look too.
Chad, yes - gears would be better - but it's also pretty flat where I would be riding it.
A few test runs will see. I used Mars braided cable with a solid core.
I did look at clamp on ones - but they are stupid-expensive for an already blown budget.
Test rides will see.