I think we are questioning frame lifetime and quality escapes during frame manufacture.
Perhaps we need to consider what kind of "tour" we're discussion? On Tourist's point, that remote place looks like the place you'd be happy to have an extra 3-10 pounds of weight on the bike to handle the stresses without breaking. Many of the "broke a frame" accounts I've read have been people on extended tours over remote roads for months on end. And like mev's and BobG's examples, it's possible the long desired frame life is frequently met or exceeded on that kind of long trip, typically with a heavy load. Perhaps a loaded touring frame has similar lifetime to an unloaded frame that's not designed, built, and used for loaded touring, but that's just speculation. And does a loaded touring bike use up some of its lifetime if used for commuting?
Quality escapes should include those cases where process variability exceeds minimum design thresholds; e.g., ordinary statistical variation in a weld or heat treatment for a dropout will occasionally result in a weld or a dropout that will fail in normal use, and manufacturing quality should be designed and implemented to catch those cases. But, as Capt. Murphy found, it doesn't always work that way. That leaves ordinary consumers and bike tourists to guess how we should plan for, or plan to ignore, the potential for our individual frame to break.
Speaking of statistics, I'm not sure whether I should believe this guy:
Originally Posted by
cyccommute
That’s not how probability works. “one in X” where X can be any number is a statement of how common something is. Consider a coin toss. The chance of tossing heads is 1 in 2 chances. Each toss of the coin can be either of 2 results. But that doesn’t mean that you can’t toss heads 3 times in a row. Tossing 50 heads in a row has a far smaller probability but it could still happen.
Or this guy:
Originally Posted by
cyccommute
Quit being so literal. “One in a million” is a conversational method of saying something is rare. I haven’t done any detailed analysis nor have I ever said I did. It’s a wild ass guess, nothing more.
...
Your 1% failure rate is just as mythical as my 0.0001% failure rate, although I think mine is probably closer to the true value. Bicycles can fail but not all bicycles fail.
Either way, my gut would need a Costco size bottle of Tums to be as calm as his gut is about the likelihood of a quality escape on a given bike frame on an extended ride.