This year I changed my primary ride to a single speed cyclocross bike with a 44X16 gear. I still ride my other bikes, but I commute and train on this one. I live in a hilly area, and most of my rides have a cosiderable amount of climbing. My arms, chest and stomach are more ripped than they ever have been, and I think it is from the SS. When i hit the hills I have to stand, and I have 4 different climbing styles depending on the pitch. Since I cant shift to a lower gear, I have to politly ask the rest of my body to pitch in - and it is definetly a full body workout. In 8 years of serious, year round cycling, I have not found a better full body workout than this. Now just send me 4 easy payments of 29.95.......