I started riding at 65 and here I am flying down this hill at 25mph. Fast for me at the time, all of a sudden I didn't have any wheels under me. Cracked helmet, torn shorts and jersey. While I was laying there testing my arms and legs, it shot into my mind, THE BIKE. I was 10 miles from where I parked. Anyhow, I have a lot more I could say about it, but the bike was alright, I had a few cracked ribs and a lot of road rash. My ribs were sore for 4 months. I would never think about riding without a helmet.
I wish you and your friend the best of luck and a speedy recovery, good luck.
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George