That is, indeed, a very interesting statistic, and a MHL advocate should have an answer for it (anecdotes are not an answer). If the ratio of head injuries/overall crashes remains unchanged in spite of increased helmet use (ie fewer unhelmeted riders), and since the evidence for the helmet is good in low speed collisions (isn't it?), there's something else going on here. I have an idea about the distrubution of crash types that would result from a MHL, but I'd like to think it through more first (crashes would get more serious, as all the casual cyclists who have low speed wipeouts in parks stop cycling due to MHL, the only cyclists left are the serious ones who ride with the cars, and a serious crash is more likely to result in a head injury than a casual spill?).

I shall continue to wear my lid, as I literally feel naked without it after all these years, but I shall be a helmet nanny no more unless some better evidence comes along. Trombone draws a crucial distinction... it might well be a good idea for ME to wear a helmet, but there could be substantial unintended consequences from an MHL that make it a bad idea.