About 6 years ago I had a bicycle accident at only walking pace. I ended up landing on the crown of my head on the only rock around. Fortunately, I won't throw a leg over a bike without a bike helmet on. The force of the blow was such that I had the imprint of the air holes in the helmet were contused into my scalp. Took a few days for that to fade. I had a severe concussion, vomiting, dizzy, blurred vision. Passersby called 911 and I spent the night in the hospital and a week in bed before I was able to walk normally.
I live in Chalong on Phuket. I drive here and find it sporting but I drove in Russia and Ukraine as well so it was not so much of a shock for me here. What is shocking though, are the numbers of people without helmets. Thai and Farang alike. People have no idea how fragile your basic brain housing unit really is. I watch the young guys on "big" bikes go blasting through, weaving and following just a few feet behind traffic. I drop back slowly so I won't be directly involved in the wreck. Once in Bangkok that was a good move and the motorcyclist, sans helmet, did not survive it. You could just see the inevitability of it all and were helpless to do anything about it except avoid. I wish everyone who rides without a helmet could see those brains leaking onto the pavement and the unseeing eyes staring wide at the sky.