Originally Posted by
Sheldon Brown
Nope. The longer "moment arm" (radius) is cancelled out by the longer one in back, if the ratios are the same. That's physics.
Your 60 tooth chainring will create less tension on the chain, so there will be less frame and BB spindle flex, and perhaps that's what you're feeling.
(Although there's less tension, the chain moves faster/farther, so the same amount of work is done.)
Sheldon "Actual Physics" Brown
For the sake of argument, if you could make a smaller diameter 20t cog and a larger 20t cog, wouldn't the larger cog create more leverage on the back wheel?