As a runner, you can draw energy from a lot of places: the scenery on your route, the sun on your skin, your favorite playlist, even the shoes on your feet. The right pair of shoes doesn’t just log miles; it helps propel you forward and adds a little more joy to the run. But that’s not something you can gauge from online photos or a quick try-on at a store. That’s why we ask real runners to take new shoe models out on demo runs—because with running shoes, first impressions can tell you a lot.

Megan Bjeldanes, a marathoner from San Diego, Calif., laced up the On Cloudmonster 3 to see what it would bring to her runs. According to the specs, it looked promising: a rocker-shaped design with three layers of Cloudtec® cushioning for responsiveness; Helion™ foam for comfort and energy return; and Speedboard® technology for added propulsion. Did all that tech translate to joyful running?…