A quick question about gear ratio. I went on Mr. Sheldon Brown's site and looked at the gear inch for 48 X 18, and it's 70.1. This is what I'm currently running and I like it.

On a bike that I'll put together soon, I will have a chainring with 49 teeth. I want to stay as close to the 70.1 gear inch as I can, so I am thinking of using a 19T cog. So:

Current: 48 X 18 = 70.1

Considering: 49 X 19 = 67.8

Or maybe even go up a little: 48 X 18 = 71.5


The question: is there a tremendous difference between these two in how I will feel. My commute will be mostly flat with some light rolling hills. I'm pretty fit, but prefer not to show up to work always drenched in sweat, and I'm in no rush on the bike.

Thank you for your help!