The quick answer is, if we paid $10 for a screw, like the aircraft manufacturers, do, we could have the same reliability.
Still, this brings up an interesting point regarding reliability in general. There are two times when any item is likely to fail: when it's old and wearing out, and also when it's new. We call the latter "infant mortality" failures, and the former "end-of-life" failures. Infant mortality failures are caused by flaws in manufacturing, which may be either random or genuinely negligent, and appear relatively quickly. Many people have the idea that a new bike is reliable; that's just not true. It's only reliable after it's been used awhile, and the infant-mortality period has passed.
Between these extremes is a period of relatively low chances of failure.
It might be fun to be smug, and note that our older bikes are well past the infant-mortality stage, and thus more reliable. Unfortunately, however, a heavily used, 30-year-old bike is probably well into the end-of-life period, in terms of failure rates, for many of its components. It's a safe bet that at least some of the components are ready to break, even though most have been reliable for a long time. Problem is, you don't know which ones are still OK and which are close to failure. Everything is, therefore, suspect; however, parts that are more stressed, like cranks and seatposts, are obvious concerns. Also parts like handlebars, which are somewhat less stressed, but where a failure could cause a bad accident.
So, what to do? The only real option is to inspect things regularly, especially for signs of cracking at stress points. These can be hard to see, and lots of scratches and plating flaws can create false alarms. Cracks, once begun, propagate quickly, so it is a really bad idea to ride a bike with a cracked component, especially something like a seatpost, handlebar, or crank.
To some degree, I realize, I'm just formalizing the obvious: old things break. Still, I thought it might be useful to explain how we technogeeks view these things.
Steve Maas (another beautiful bicycling day in) Long Beach, California (but I gotta work. Bummer.)
Mark Poore wrote:
> It always raised the question to me, why can they make airplanes and such that are dependable, but when they design and make seatposts and the like there is a history of failure. Kind of scary.
>
> Mark Poore
> Slatyfork, WV