“We were at an altitude of 15,000 feet on Mount Haizi. It started to hail. The temperature dropped to 40 degrees. We were only wearing t-shirts. They didn’t stop biking.” It was photographer Wang He’s second time on the Tibetan Plateau. The first hadn’t gone so well—Wang had ended up in a hospital for altitude sickness. But if he worried about whether he’d make it through his 23-day shoot along one of the world’s most treacherous roads, he had a harder time imagining how his subjects, 42-year-old Wang Chao and his 12-year-old son Runxi (who had never been at this high an altitude before), would complete the 1,300-mile trip entirely on their bicyles, as they had planned.