Re: OY! Florida! OY! Sprockets!
no. it isn't the length of the chain that changes the ratio.
the derailer is to move the chain when there is more than one gear.
look at the chain. each tooth goes into each link.
now look at the chain @ the top of the gears.
they are directly connected.
if you notice many of our bikes use an idler pullry. (some even use a gear.)
it doesn't change the ratio one iota.