I need to know the Circumference of the wheel right?
Aren’t those tyres a standard 27 x 1 1/4"? Sheldon’s gear calculator will let you select that from the wheel drop-down.
yeah those standard 27 x 1 1/4" wheels. - I guess they are 27" Nominal.
that last one gives the same Gear Inches for a 27" and a 700c but these are two different sized wheels.
just use 27" for the wheel size:
gear inches = 27 * chainring / cog
That’s what most people use for quick comparison. The difference between 27" and the actual rollout of a 700c wheel will be about 2", but it matters little when you are comparing gear ratios.
For a 27" wheel, just keep in mind that you’ll probably end up with a very slightly higher gear than your mate with the same chainring/cog on 700c wheels.