Luge looks silly. It looks easy, too: lie down on a sled, let gravity do the work, climb the podium. In reality, of course, luge is fascinatingly complex. And, as American Emily Sweeney’s brutal crash this week made clear, it's dangerous too. A good start is crucial (that’s where the gloves with little spikes on the fingertips come in). The rule of thumb says every 1/100th of a second you lose up top compounds to 1/10th of a second by the end of the run.