Evening all, I am in the middle of trying to understand the physics behind how gear ratios work on a bicycle. I have a typical road bike with a rear 10 speed sprocket and 2 front chain rings. What i am trying to understand is when you switch to a larger cog in the back it becomes easier to pedal but when you switch to the larger cog at the front it becomes harder to pedal. I was under the impresion it has to do with the number of teeth on the cog doing the work but obviously I am wrong in this theory. Any help would be much appeciated.