would probably be about 1985/6. My first bike was an ‘orrid Apollo from Halfrauds, with ‘Oversized Tubing’ hmmm, oversized, and heavy, hi-tensile steel frame, 15 gears and some sort of suspension forks.
Second bike (after the first one got nicked) was a Shogun Trailbreaker with STX-RC bits and rigid forks.
Third Bike was a Giant Boulder Alu-shock, 21 gears, suntour forks, bought in 1999.
Current bike, Orange G2, got last year.
So at the moment i’m averaging about 8 years per change of bike. (if you count the first two as one bike!)