Ron at IVO prop sent the following reply.

What is the gear reduction ratio?
2.58 or 2.62 use Ultralight Left turn viewed from the rear 3 blade 68
inch diameter.
3:1 use meDium 2 blade 68-72"
3.47:1 use meDium 3 blade 68-72"

Not a very talkative dude, but anxioius to make a sale.

Mark
Kitfox III- 582 (#1050)