This is the time of year when I realize that, as tough as my spin class is, it's only an hour long.

Once the weather warms up and the days get longer, my bike rides, hikes, and walks suddenly get much longer too. And I don't always have the energy or stamina to keep up.

For years, more experienced cyclists have told me about energy gels -- single-serving, easily portable quick calorie fixes designed for athletes. Many cyclists eat one for each hour they spend on their bikes.

The advantage of energy gels is that they provide calories and carbs to cyclists, runners, climbers, and other endurance athletes who don't want to eat energy bars because they can be hard on their stomachs or interrupt their workouts. And unlike energy drinks, the gels are easy to stash in a pocket.

I'd never tried them before because one of my credos in life is that if I'm going to indulge in high-carb calories, I'd really prefer that they come from wine or chocolate, but after a particularly long ride the other day, as every pedal stroke got heavier and heavier, I thought that maybe they were onto something. So I decided to buy a couple and start carrying them on my rides.

Turns out, the world of energy gels can be pretty confusing at first. There are several brands, with names like Gu, Hammergel, Carboom, and Power Shot, and they come in various flavors ranging from espresso to tropical fruit. Also, they're sort of pricey, running about a $1 a pop.

I bought half-dozen and decided to road-test them for myself. About.com offers a helpful list of their top picks, along with a few product reviews.

Once you get used to the funny texture, the gels work pretty well. Maybe it's the power of suggestion, but I popped an espresso-flavored gel (which contained caffeine) during a tough, hilly ride and felt stronger and ready to keep climbing steep hills.

I'm not sure that I'd be able to leap tall buildings in a single bound, but then, I haven't tried a lot of the other flavors yet.