Oscar Pistorius is a world class Olympic sprinter. He’s also a double, below-the-knee amputee. What allows him to compete is a grit that most of us can only imagine, along with a pair of Össur’s Flex-Foot Cheetah legs, J-shaped carbon fiber prostheses that fill in for feet and calves.

By now, you’ve surely heard of Össur legs and Pistorius’s watershed Olympics qualification. But what you may not know is a design problem that had to be solved first. Whereas every sprinter competes on spikes, Össur legs are smooth carbon fiber bands. So how do you affix spikes? By hand. Roughing up the surface, strong fixatives, and lots of brute force.

Even for a famous athlete of Pistorius’s resources, his spikes were a logistical nightmare that took two hours to replace. His trainers were worried about the ongoing impact of the Össur legs on his knees. And, because the spike work was totally manual, there was a lot of inconsistency on the fit of the tread (and thereby, the traction Pistorius could expect, especially during wet races).

Luckily, Pistorius is sponsored by Nike, and one of the perks of a Nike sponsorship is access to the first wave of technologically superior equipment.