Longest was around fifteen years, until 1988 when I bought my first mountain bike, a Stumpjumper, and more recently about four; I came off hard at low speed on a cycle path after turning off of a road, both wheels went out from under me, and I hit the ground hard, cheekbone, side of my head, shoulder and left kneecap. No idea what happened, no major damage like some people, but my knee has never been right, and gets pretty painful, and I’ve just lost all confidence in the bike staying upright.
Looking at some lightweight RF d3o pads to give me the confidence back and get the bikes out of the shed and out on the roads and trails again.