Shoes rated "Not Walkable" have smooth carbon soles with exposed 3-bolt cleats sticking out from the bottom. That makes walking awkward, slippery, and tough on your cleats—but it also delivers the absolute best power transfer you can get. Every watt you push into the pedal goes straight to the drivetrain with zero sole flex.
These shoes are built for road racing and time trials, where you're clipped in for the entire ride and off-bike time is minimal. If you're chasing performance, that exposed cleat design is a feature, not a flaw—it allows a wider, more stable pedal platform and the stiffest possible sole construction.
The tradeoff is real, though. Even a quick walk across a parking lot feels clunky, and cleats wear fast on pavement. If your rides include cafe stops, bathroom breaks, or any regular walking, consider shoes with at least limited walkability instead. But if you live in your pedals, non-walkable shoes give you the best on-bike efficiency available.