This is a perennial question, and for good reason: Every gym or health club has some form of indoor cycling class, and in the dead of winter it’s tempting to jump in rather than face the elements or slave away on a trainer alone in your basement. There’s nothing inherently wrong with these classes, but it’s important to find one that will actually improve your performance on the bike. I encourage athletes to evaluate classes based on how well they address the core principles of training: overload and recovery, specificity, individuality and progression. I address each of these below.

Overload and Recovery Classes generally fall into two categories: sufferfests and structured workouts. Both have their merits, and I understand the psychology of the sufferfest fan’s desire to reach the end of a class exhausted, but as a coach I prefer the latter approach. Though a sufferfest might feel excruciatingly difficult, your actual power output may be too low to improve your fitness due to inadequate recovery periods. Check in with the instructor: If the primary feature of the workout is that it’s ridiculously intense, but he or she can’t identify what you’ll get out of it, find a different class.

Specificity The fact that you’re pedaling is a step in the right direction, but some classes have very little to do with actual cycling performance. And that’s okay— I’m all for classes that burn calories and get people sweating. But if you’re looking to improve your performance on the road or trail, you need workouts that target the energy systems and power demands of actual cycling. These classes can be harder to find because effective interval sets are often not the most entertaining, crowd-pleasing kind. The intensities are consistent and repetitive instead of all over the map, and while you may do some pedaling out of the saddle, no cycling-specific class will have you doing push-ups on the handlebar.

Individuality This is where technology comes into play. The absolute best indoor cycling classes use power meters, whether that’s in the form of CompuTrainers, power- equipped stationary bikes or personal bikes with power meters. And the best ones also set individual power-training ranges for each athlete. The next-best scenario is a class that uses heart-rate monitors and individual training intensities. The self-selected “turn the knob to the right” method is fine, but not optimal.

Progression Progressive classes are pretty rare, and to find one you’ll most likely need to go to a cycling performance center. To address the progression principle, a class needs to be designed with the idea that the same people will be coming back week after week, and that the workload will thus take into account the developing fitness of these participants. In the standard gym model, in which classes are accessible to anyone anytime, the programming tends to be static. (This is also partly why these classes often are sufferfests.) In a progressive class, some of the workouts may well be more moderate in intensity, and while that’s good from a long-term training perspective, it’s not as appealing to the intermittent class user.

Then Again… Incorporating indoor classes into your winter training need not be an all-or-nothing proposition. There’s nothing wrong with an occasional—even weekly—sufferfest. Even cyclists following well-structured, scientifically based, progression-driven indoor programs sometimes should forget the numbers and just open the throttle.

But if all you do all winter is pummel yourself, your progress will be blunted. The best option: Follow a scientifically based program, but incorporate some “hard for the sake of being hard” classes, just for fun.