I wouldn't say it hurt him or didn't make a small difference but it looked to me like Jens hit face first (Y'know. The part the helmet doesn't protect) and anyway, what about Sonora, Fujinawa, Reinhart, Hailey and Lemire? They all died wearing helmets, didn't they?

AFAIK, the tour has had 2 deaths. Just because riders crash, doesn't mean they'll die each crash.