Giraffe sprocket question

My 5’ giraffe has a 28 tooth sprocket on the top and bottom, with a 20" wheel. If I change the bottom sprocket to a 14 tooth sprocket, what would the equivalent wheel size be?

lets do the math 28 divided by 14 is 2. 2 times 20= 40 so i guess it would be a 40" wheel.

Thanks, I thought half the sprocket would double the wheel size but I wanted to be sure.

Oh, and I don’t do math!

Might want to check. Some of the lower sprokets on chain driven uni’s are spot welded to the hub. If so, it also makes it pretty hard to repair a spoke if the wrong spoke is broken.


I did the research on that already and found out the lower sprocket is a screw on. I’m in the process of putting a 21 tooth on the lower. Can’t wait to fly!