Rider Fails to Pay Attention, Brakes Hard and Spills [Video]
The rider in this video wasn't observing the traffic as careful as he should have. If he paid enough attention he'd most likely noticed the other cars are slowing down. Even more, he was obviously riding his bike too close behind the pickup truck, thus leaving him will reduced space for evasive maneuvers.
You can see how late he brakes, proving once more that the sudden braking of the truck in front caught him unaware. In the end, as bad as things went, we still might say the rider was lucky: he was spared a head-on collision with the truck, which would have caused extensive damage to the Goldwing and resulted in severe injuries.
Also, please note how closely the runaway bike misses crashing into cars coming from behind. A broken mirror and some scrapes are easy to fix, anyway.