FG riding oobservtions
I've been riding FG for about a year. Got my bike dialed in with low rolling resistance tires, light wheels, and Frog pedals. It wasn't fun with draggy ThickSlick tires, heavy Origin 8 wheels, and toe clips with sneakers. So nice and fun now, dramatic difference.
I alternate days with a geared bike. Ride the least hilly 18 mile route on days I ride the FG, and avoid it when it's windy or real hot. I've noticed conditioning improvements and my legs have developed the features attributed to riding FG, they are more supple. Which means to me they are more comfortable mashing a big gear, or spinning fast.
Analyzing the conditioning benefits of riding FG, I've come to the conclusion the main reason is that FG is inefficient. It has marvelous efficiency in a narrow range of road conditions and speeds, but I don't live in Kansas or Florida.
Proof of its inefficiency is that is why geared bikes were developed and mostly replaced them, they are more efficient.