When I was a teenager, a mate left his bike at our house one night and walked home as it had got dark and the bike had no lights. I agreed to ride it down the hill to his house the following day.
Following day, I'm bowling down the steep hill towards the busy traffic-light controlled junction. Pull on the brakes; the rear one doesn't work. The front one does - until the cable snaps.
As I approach the junction at what feels like 90 miles an hour, the lights turn red and the crossing traffic starts up. Looking for an escape route, I spot a school entrance on the right and head for it. The bike doesn't like the turn at that speed and starts wobbling.
I miss the gate, and fortunately collide with a metal litter bin (manufactured by Listers of Dursley, Gloucestershire) and a sign post. Fortunately, because behind them is one of those spiky-topped wrought-iron fences...
The bike and the bin were write-offs. The post was severely bent. I still have a scar on my knee.
Helmet? No-one had heard of bike helmets in 1982.