Vrije Universiteit revived a 1894 skate patent by explaining its mechanics

German inventor Karl Hannes patented a hinged ice-skate design in 1894, in which the blade attached to the boot only at the toe and could swing free at the heel during the push-off phase of a stride, rather than staying rigidly fixed to the boot the way every standard skate blade did. The design attracted no serious competitive use and was treated by the skating world as a curiosity for nearly a century — an idea tried once, found unremarkable, and abandoned.

Starting in 1979, Gerrit Jan van Ingen Schenau, a biomechanist at the Vrije Universiteit Amsterdam's Faculty of Human Movement Sciences, began studying the mechanics of the speed-skating stride for his PhD research and identified a specific inefficiency in the fixed-blade skate: because the blade stayed rigidly attached to the boot, a skater's calf muscles had to stop contributing force early in each stride, well before the leg finished extending, since further ankle extension would have lifted the blade off the ice entirely.

Explained the hinge's mechanism—a fixed blade cuts off calf force early, a hinged one lets it contribute longer—then proved it with a 6.25% time gain.

The original rejection was based on incomplete analysis, not a real flaw.

Van Ingen Schenau identified the specific inefficiency in fixed blades.

The hinge let calf muscles contribute force longer, a clear mechanical advantage.

The performance gap was large and unambiguous, converting skeptics.

Before assuming an old idea was correctly rejected, check if the rejection rested on incomplete understanding of the mechanism rather than a lasting flaw.

De Jong won the 1997 European Allround Championship on clap skates, defeating seven-time defending champion Gunda Niemann-Stirnemann, who publicly argued the skates should be banned — instead, nearly every top skater switched to clap skates by the following season. In the 1997–98 season, nine of the ten men's and women's world records fell, with the men's 1000m record improving by two full seconds in a single season after taking 16 years (1980 to 1996) to improve by the same margin under the old skate design.