Many cyclists consider indoor training a necessary evil. Spinning, as it was dubbed during its rise to health-club ubiquity in the eighties, hones technique and provides the kind of intense workout that's hard to get in winter. Pros swear by it. And it's about as fun as indoor ultimate Frisbee. You want me to ride nowhere when I could be out skiing?

In previous years, I'd pass, emerging from hibernation several gears slower than my basement-trained buddies. Determined to avoid the humiliation this year, I signed up for Cadence TV, a new on-demand video service that allows you to participate in group cycling sessions via the Internet. Designed by Cadence Cycling, a high-end Philadelphia-based training facility, Cadence TV is the latest evolution in online coaching. There are other downloadable workouts available, but Cadence is the first to let you to join an actual—if virtual—class.

My first challenge was setting up an exercise station. This meant hitching my road bike into a stationary trainer in my living room and positioning my laptop on a stool. Cadence loaned me a PowerTap rear wheel, which measured my output in wattage, so I could track my improvement over time. It took me a few dry runs before I got everything dialed—Internet working? Water bottle full? Dog that barks incessantly at whirring flywheel stowed outside? At last I was grunting my way through my first workout, pacing the other clients, who were visible on my computer monitor, through intervals and drills (one-legged spinning, anyone?).

I could see immediately why this makes someone a better rider. By the end of the workout, I was exhausted, a pool of sweat glistening on the floor. My laptop provided a numerical display timing each interval, and the coach barked audio prompts. Since I didn't have to deal with the road's variables—cars, flats, gnats—I could just sit and spin.

Watching my classmates was about as exciting as watching C-SPAN's Washington Journal, so I supplemented with iPod mixes and TiVo'd stages of the Tour of California. Soon I began to look forward to my multimedia indoor sessions—my sound system thumping, the coach urging me to keep up my rpms as I chased Team Astana through the Sierra Nevada. True, I was actually in my living room on a drizzly winter morning. But my legs already thought it was May. >Cadence TV costs $35 per month, with a minimum three-month sign-up; cadencecycling.com.