Have found I have got a lot
fitter riding SS. I guess it's a combination of a few things
1. Cadence...when you run gears, to a certain extent, you can stay within the cadence you a comfortable with. No such luxury with a SSer. I never used to spin very quickly, but now I have to, sometimes....short bursts at max sure gets the heart pumping.
Going up steep hills takes some getting used to...but each week the big ones are getting easier and easier = I must be getting stronger.
My biggest challange is one hill where I would have to stand up to pedal from bottom to top....now I can ride the first half sitting down. Want to do the whole thing sat down.
2. Upper body....I personally use more upper body strength SSing...heck, my moobs are down to a B cup
3. It's just MORE FUN....so I go out more.
Of course, these are just my personal experiences....otherwise may, and no doubt will, disagree
For ever changing my mind and my cars