General Surgeon.
And yes-loads of trauma experience.
And no I do not wear a helmet, there simply is no data that is of ANY value in regards to bicycling.
And yes, I also am a motorcyclist and would never think about going any distance on a motorcycle without a full face helmet.
And yes, there is absolutely no data that does not show a marked reduction in head injury rates and deaths with motorcycle helmet use.
And yes, this absolutely is not true in bicycle helmet use.
Virtually any study supporting bicycle helmet use in reducing head injuries refer to the study by Thompson et. al. published 1989 in NEJM. The study is a terribly flawed one and yet remains the cornerstone of helmet safety.
When looking at whole population studies, bicycle helmet use not only fails to show ANY reduction in fatalities or deaths, some actually show an increase in death and injury rates.
This is in complete opposition to motorcycle helmet use where virtually every whole population study of helmet use shows marked reductions in death and head injury rates.
In bicycling, anecdote rules and in medicine, especially as applied to bicycle helmet use, anecdotes are of little value.