KC8QVO

As for the retirement of a bike question - that is a loose question. The way I interpret what you are asking is the frame and fork. That is "the heart" of "the bike". There are so many other components that tend to get swapped around and replaced - wheels (if not broken down to rims and hubs), cranksets, stems, handlebars, shifters, derailleurs, etc, etc. Now - if someone had the same wheel and crank sets on their bikes for 100,000 miles I'd be impressed. So again, so me, the way I interpret the retirement question is you are asking about the frame set alone (frame and fork, nothing else).

There are are 3 conditions I can think of that would be cause for retiring a frame set due to mechanical reasons:
- The fitment between the fork and frame in the head tube becomes wallered out due to improper fitment causing accelerated wear, or normal wear over a long period of time
- The welds (or brazed joints, either construction method) of the frame and/or fork show signs of stress cracks indicating the frame and/or fork are failing
- The dropouts show signs of weakening or the position the axles ride in are worn excessively

Aside from the frame and fork components (the raw metal of the bike structure) everything else can be replaced when it is worn out. Just like ball joints in a car - yea they are part of the "structure" of the car and how it functions, but they are ultimately a "wear item" that can be replaced when worn out. You don't need to trade your car in, or trailer it to the junk yard and sell it off for scrap, just because a "wear item" is worn out. Same with a bike.

My Disk Trucker has somewhere around 4,000 miles on it, not quite. I lost my biking data when I reformatted my HD a couple years ago. I thought I had everything backed up to an external drive but apparently the bike folder didn't make it. So I don't have a way to tell exact mileage. I know that isn't a lot of miles in the grand scheme of things, but for me it is considering what my schedule was and how much riding I fit in.