I absolutely LOVE spinning! When you have a good instructor with good music that is. Otherwise it can be very tedious. I find it to be a great cross trainig workout. The gel seat cover is a good idea without investing in the bike shorts. I would also invest in a heart rate monitor. I've done a lot of researching, and thru trial and error found out that when you let your heart rate stay too high for too long, you end up burning glycogen (carbs) instead of fat. I leave the class and could eat a dozen bagels. Now, this doesn't happen to everybody, but several great spinning instructors told me to keep my heart rate at about 75% most of the class, and I don't walk out wanting to eat a bagel factory. They confirmed what I already knew. Anyway, hope this helps. Spinning definitely made my legs stronger. As for firmer...well, my legs are my big problem area, so I don't know what will ever help! But then again, I never made it to class more than 2x a week. The rest of the time is CAthe, elliptical, etc....