The cyclist may crash into fixed or moving objects, or
> simply slip on a loose surface and fall on top of the bike. Or the bike may
> simply fall over when parked an be dented by striking an object. Thin wall
> tubes may in these ways sustain serious damage without ever failing in the mode
> tested in the lab.
This is very much a concern with certain tubesets. El, for example seemed to dent easily if it was treated badly. Some of the newest stuff, though is extremely dent resistant. I keep a Platinum tube around the shop that people can test bang over a post or something. They are amazed at how hard you have to hit it to get it to dent. The thicker walls of traditional tubesets do fend off blows a little better than the average tube nowadays.
Hardening tubes introduces another set of concerns. I
> believe Brian Baylis or Richard Sachs recounted in a past thread that early
> samples of 753 were so brittle that when a tube rolled off a table, it would
> sometimes shatter on the floor almost like glass.
This must have been way back. I have heard of bad batch of 853 (early on) but as far as I know it has excellent reliability. The other tube manufactures have had excellent quality control and I have heard of no problems.
And Reynolds was concerned
> enough about the fragility of 753 to require certification of brazers, insist on
> silver brazing, and strongly recommed against chroming.
The brazing certification was very easy to pass, never heard of anyone failing it. Like all thin wall tubing, you should never chrome modern tubesets. Unless its done perfectly, chroming can cause serious damage. The thicker tubesets could handle some damage from the acids used and overzealous polishing but its not worth risking it on any modern set.
Personally, I insist on a lot more
> robustness and believe that an lb or even a kg more or less, except on the
> wheels, is hardly noticeable. So I have no use for 753 or any of the newer thin
> walled tubes. I just hope we continue to have the option of purchasing 531 or
> an equally robust tubeset in future years.
Personally Jerry, I agree with you, what is an extra pound between friends. It doesn't make my ride any less fun and makes for a great riding bike but there have been legitimate advances that allow me to make a stiffer, stronger, just as long lived bike. Lets not forget that overall the frames from the modern American framebuilder are infinitely more reliable than the many broken frames that I have seen from the hallowed frame shops of Europe.