The replies to these posts fell into three groups:
1. Cyclists who’ve never had a severe crash involving their head but are happy to wear a helmet
2. Cyclists who’ve had a severe crash involving their head and are happy to wear a helmet because it saved their life
3. Cyclists who’ve never had a severe crash involving their head and are happy •not• to wear a helmet because they insist it doesn’t make a difference
One quadrant is notably absent.