Well, the operative words here are casual riding. I ride relatively flat landscapes and my speeds and distances are modest. Compared to a well set up road bike, efficiency , I'll guess, must be down by 50% on an upright 3 speed. There's no pull on the crank, my upper body muscles aren't doing anything besides holding me up and wind resistance is much higher. This is why I like them geared down a bit. Considering all that, an inch or two of leg extension doesn't amount to much. What I gain is the experience of riding with my upper body in the same position as I was walking. Except I'm not walking. I'm gliding through the countryside with the wind in my face taking in the surroundings. I really don't notice a big difference between my 21" and 23" or my 24" roadster as long as I take my rides nice and easy. If I want to get somewhere in a hurry or deal with hill climbing, I have a drop bar road bike for that.