Painful lessons must be passed on to fearless young daredevils.
Had a major crash on my bike last week. Coming back down the Taff Trail on the return run from Merthyr Tydfil, I thought the boy of around 16 had seen me and so I didn't slow down. However, as I came up on him, he became startled and began darting back and forth across the path. Having wrenched the brakes on, I went left-right- left-right-left before the inevitable happened. I hit him. Fortunately, I managed to strike him only with my chest rather than with the bike, and he harmlessly dropped to his knees on the grass.
Unfortunately I had no contingency plan of my own, and lost the bike in a huge skid before it flipped back and landed on top of me.
He was on his feet first and helped me up, full of apologies. Having felt it was my fault, I also said sorry, and we spent a couple of minutes brushing each other down and being contrite.
Best thing is always to get back in the saddle, so I was taught. But since this happened just outside Caerphilly, it was clear I had something of a trek back to Cardiff.
Both my knees were killing me, I had a blood bruise the size of Brazil on my inside thigh, the fingers on my left hand were in agony from where the bike had landed on them, I twisted my left wrist and I have a loose tooth (haven't figured that one out yet).
I was also in shock. I realised this because every time I came to one of those cycle stiles they have along the Taff Trail, I fell off.
I felt I had to get drunk the next night because the pain it caused was bringing back memories of a huge car crash I had 10 years ago.
Pain is a bizarre thing. The older and bigger you get, the more it hurts and - crucially - it begins to traumatise you.
Not a week beforehand, I'd watched my youngest son Tom bomb back and forth around my parents' Mid Wales farm, occasionally getting into the same sort of sliding skid-crash I experienced, yelling for a minute or two, and then getting back on with it, hardly allowing his mother or me enough time to patch up the grazes.
He's also had a lecture from me about taking care of his spine when he asked me what it was a couple of weeks ago, along with pretty much every other part of himself.
Tom's such a fearless daredevil, I know he will get to my age and feel all the creaks and groans that come from a lifetime of caring not if you put your body on the line.
They won't thank you for wrapping them in cotton wool, but I sometimes wish I could stop him from feeling the aches that I do these days.