I commute to work with my regular, non-e bicycle, sharing the road with cars. I wouldn't dream of not wearing a helmet, even at "just" 25 km/h, though for most of my commute I keep speeds above that (up to 50km/h).
My 18 miles commute is 2 miles of sleepy suburban traffic and 16 miles on the SF Bay Trail (IOW: flat dirt track with no cars allowed.) Even if it were all dirt track, I'd still be wearing my helmet.
My 18 miles commute is 2 miles of sleepy suburban traffic and 16 miles on the SF Bay Trail (IOW: flat dirt track with no cars allowed.) Even if it were all dirt track, I'd still be wearing my helmet.