Yesterday, a little more than a year after the events chronicled in this book, something terrible happened that changed everything. Jure Robič was killed in a training accident. This invincible athlete and the main protagonist in Hell on Two Wheels died at the scene when he collided with an oncoming vehicle while barreling around a tight downhill turn on a quiet, unpaved fire road in the mountains a few miles from his home in the Slovenian countryside. Jure leaves behind a young son, Nal, and a huge number of grieving friends and admirers.

He was only 45 when he died and still at the peak of his athletic prowess, having won three ultradistance races in 2010: the 732-mile Race Around Slovenia in May, his record fifth Race Across America in June, and the 1,050-mile Tortour de Swiss in August. By many accounts Jure Robič was the world’s greatest endurance athlete, dominating most of the races he entered throughout a storied career that included 100 victories and 150 podium finishes.

Jure’s passion and courage touched everyone who met him, and the shock of his death sent the tightly-knit ultracycling community into paroxysms of anguish. Hundreds of admirers cycled to his funeral in the mountains near his home in Jesenice, Slovenia, to pay their respects and offer condolences to family and friends, and more than 60,000 fans remembered him on a memorial Facebook page within days of his passing (you can find it here). It’s hard to believe this indestructible king of ultracycling is gone; his death leaves a gigantic void.

I came to know Jure as I researched this book. He touched me deeply even though our encounters were limited. Nobody who met this attractive, charismatic man could ever forget him.

All day I’ve been trying to put it into words what made Jure so compelling to others. He toiled alone, away from fans and cameras, in a sport that is far outside the mainstream. Yet news of his death echoed around the world. This is in part because Jure worked hard to help people see his essential humanity and to understand what made him tick. Everybody wanted a piece of him, and he rarely waved his fans off. But I think it really comes down to this: Jure’s persona spanned extremes, making each more accessible to the other. He was the toughest, baddest endurance athlete on the planet. But he could also be unnervingly vulnerable, surprisingly humble, and completely genuine. These personality traits rarely mix. But in Jure they did, which is why everybody who met him could relate to him and find something to learn from him.

Today I’m in shock that Jure is no longer with us. But even now—especially now—the story of this man’s life and unique style of racing can still stir and astonish us. Jure, wherever you are, your power no longer turns a single set of cranks. Today you are the motivating force inspiring thousands to test their own limits and break through personal barriers, just like you did over and over again.

Read a news account of the accident here.