Feel the burn. Muscle burn, that is. We’ve been spending a few months with the Hammer Stepper—a fitness bike that takes the stationary stair step trainer to the streets. The Stepper is a great innovation for anyone who wants a low-impact exercise without the hassles and expense of a gym membership - a concept that has us asking, “What took you so long?”.

For the best workout and most power, you rock the handle bars from side-to-side (like kids on an old BMX bike), set your feet at the very end of the wooden planks… and step away. But this bike is totally seat-less, so riders are forced to have better posture than on an ordinary bike. The 8-speed Stepper Hammer model we tested looks pretty tough in flat-black. And it proved to be a lot of fun, too. But make no mistake: This isn’t some laid-back beach cruiser—it’s a fierce workout. Virtual hilly terrain is a direct challenge to your thighs and gluts, unless your name happens to be Lance Armstrong. A half-hour on this bike—even on flat terrain—and you’ll be sweating.

Downsides? The awkward shape and the heft of the frame do make it difficult to transport—and even harder to maneuver in tight surroundings. Though we did manage to cram it in the back of our long-term Honda Fit. And it takes some time to get comfortable with this bike as well, especially with starting and stopping. First gear is rather tall, so a regular bike would probably leave you in the dust from a stop—it could probably use one gear lower for an easier launch. And at $799, this bike isn't cheap. But it does look cool and provide a serious low-impact workout in the great outdoors. We’ll take that over a crowded gym any day.

—Ben Stewart and Brittany Marquis