Have started out on bikes back in the early 1970s I kind of grew up with the principle back then that by 20,000 miles what ever one was riding was 3 parts worn out!
I'm fortunate to be able to work (very ) part time in the Triumph Factory Visitor Experience (FVE) facility at the Hinckley Triumph HQ, we often see visitors bikes with 50,000+ miles and many at double that, I've seen a couple of 2.5 R3' at 60,000+ miles. The 2.5 is lightly stressed and heavily over engineered, cared for with regular clean oil and maintenance these bikes are capable of covering massive mileages.