good good interval workout. 3rd movie in the spinervals line up. first time using it today. the only harder workout i've ever done is my 8 mile, 6.5% average climb in the middle of august. Great for those without a lot of time during the week, like myself. Takes about 50 min with warm up and cool down. Good if you want to work on your heart rate stuff(high intensity), or if you lack on the flats and want some speed, especially explosive stuff like longer sprints or breakaways. i did all of it, and i did most of it in the suggested gears, or at most one or two cogsaway from it. Oddly enough, the hardest part wasn't the intervals, but the "tempo" sections, of which there are two. They consist of 5 or 4 minutes of 10 to 15 seconds standing, then sitting.....for the whole time. It would be nice to have a HRM for this, but other than that all you need is a bike, some water, and a trainer. BTW, bring a towel, you work up a nice steady sweat without the wind cooling you down. P.S. : the included pump up music is suprisingly 80's, but the bikes aren't ....