Sometimes it's easier and safer to get moving on in-line skates than it is to stop. Traditionally, in-line skaters stop by balancing on one skate and extending the other leg to force the heel-mounted rubber brake pad onto the pavement, a maneuver that doesn't come naturally to beginners. And the brake pad doesn't work well on slippery or gravel surfaces. To give skaters a helping hand, Concept Sports LLC in Warwick, R.I., developed a compact brake that fits on the axle of skate wheels.

A side load on the wheel from outside to inside activates the brake. Loads are normally in the opposite direction during skating. The brake is comprised of alternating pairs of rotating and stationary alloy-steel disks interleaved with Kevlar-reinforced friction pads, all mounted on a nonrotating inner hub. A keyed sleeve inserted into the wheel bore holds the brake between the wheel's bearings.

When a skater pulls the skates together while keeping the wheels on the ground, the inward force compresses the disks and the pads produce a braking torque proportional to the applied force. An elastomer ring in the brake sets a threshold for brake activation. Several wheels on each skate can carry the brake.