Originally Posted by
old's'cool
Sixty Fiver my apologies, I didn't take care to re-read your post before I posted my response, and I obviously didn't register correctly the gist of what you wrote. However, the essence of what I getting at was the concept of "old age". I'll reiterate, finished metal products do not age with time, only with use or through chemical processes (e.g. corrosion or temperature).
No worries... I am well aware that unless materials are subjected to stress that they will not fatigue and "old age" referred to bicycles that have been kept in somewhat regular use and find that most are not maintained at an acceptable level.
I re-laced the wheels on my 1957 Peugeot as despite having nearly no miles and perfectly true rims the spokes developed some significant corrosion from being stored for most of the bicycle's life.
I build wheels for a living... understand quite well how improper tension will greatly shorten a wheel's service life and deal with a lot of wheels that have relatively few miles that have serious issues due to poor builds.
I do not know what the fatigue limit is for spokes as this is determined by the quality of the build and the type of use they are subjected to and when you are dealing with a wheel you have no history of it is always prudent to replace the existing spokes.
This is why most shops will not re-use spokes as they cannot guarantee the work... my experience is that a properly built wheel will stay true and need very little attention and that the rim will wear out before the spokes do.
A few of my bikes have had their rims replaced several times and I have re-used the existing spokes knowing who built the wheel (me) and what the useage was like... some of these spokes have seen 30,000 miles and the rebuilt wheels stay as true as the originals.
Modern spokes are so much better that what was available 40 years ago... was not building wheels then but have serviced a lot of bicycles that are much older than this.