[QUOTE=Princhester]
Bear in mind that the “aerodynamic” lump at the back of a bike helmet is also a crumple zone. When the back of your head hits the road, that bit absorbs the shock. Wear a ogdamned bike helmet. Not some helmet designed for another purpose. Looking the part won’t kill you. Hitting the road might.
A friend of mine came off after being hit from behind. He’s a tall guy and he landed smack on his back from about five feet up. He was fine. Then he saw that the back of his helmet, (that lumpy aerodynamic bit you are whining about) where his head had hit the road, was compressed to 1/3 its original size, and the hard shell was split in two. He nearly threw up from shock, thinking what his head would have been like if his helmet hadn’t done what it was supposed to do.
[/QUOTE]
Oh god, not this again.
Yes, helmets are a good thing. No, they are vanishingly unlikely to save your life. Skulls are mighty strong. Bike helmets are rated for accidents equivalent to hitting the road at between 7mph and 12mph, depending on how stringent the rating it meets (guess whether most helmets on sale meet the higher standard or merely the lower - and therefore cheaper and easier to meet - one?)
I wear a helmet because I’d rather a bit of foam hit the road rather than my head. But I know that if I hit the tarmac at the kind of speed that would be likely to kill me sans helmet, I might as not be wearing one.
Why do people find this so hard to understand? By all means wear a helmet as it can protect you from minor injury, but the vast majority of people with “A helmet saved my life!” stories would have been fine without them.
But the helmet was all crushed/split, so that would have happened to my skull! No it wouldn’t.
Point 1: polystyrene is a lot softer than skullbone. Of course it crushed. Your skull has been designed by evolution to do a damn good job of protecting the mushy bits inside from impact.
Point 2: the helmet greatly increases the circumference of your head. There’s a good chance that your head might not have even hit the ground at all if you weren’t wearing it. Humans are very good at instinctively protecting their heads, but of course the instinct is based on the actual diameter of your head, so if your head is effectively larger, it’s more likely to hit the ground. Related point - I park my bike in the basement car park at work. It has a low ceiling, with beams and air-con ducts protruding from it. Walking around it without my helmet on, I’ve never hit my head. When I put my bike helmet on, I often bump my head on the beams because of the added size of the helmet which my spatial awareness doesn’t instinctively allow for.
I’m not trying to stop people from wearing helmets - as I said, I wear one myself - but please don’t repeat the mindless bullshit about them being lifesavers.
I don’t remember them being heavy at all. I remember my finger getting snagged a few times when the thingy went against the wheel (I actually never had one. But the cool boys did and I soooo wanted one --of the lights, that is. 
).
Really, I feel I got excellent service, and the bike they sold me is probably the bike I need. Maybe I’ll even want that bike in a couple years once I’ve gotten back into riding like I did when I was ten. I just don’t like it and never rode it.