My concern about "improved" steels is that they claim to have a higher yield strength, which I'm sure is the case, but my understanding of yield strength is that it is tested by securing a sample in a testing apparatus and appling uniformly and gradually progressively greater force until the sample fails. In the real world, damage to a bicycle frame is from much more random and unpredictable sources. 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. 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. And Reynolds was concerned enough about the fragility of 753 to require certification of brazers, insist on silver brazing, and strongly recommed against chroming. My reaction to this info on 753 is, "Why would anyone want a bicycle made of this stuff?" The answer, I guess, is that it is fine as long as you're a sponsored rider who doesn't pay for frames, or if you're convinced you'll never crash or drop the frame (rather naive I think), or if you are willing to accept writing off the frame after any significant crash and living with dents from minor incidents as the price of riding a lightweight frame. 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.
Regards,
Jerry Moos
Richard Rose wrote:
> Two good sources are http://www.torelli.com or http://www.columbustubi.it. Jerry, I wonder
> about your thoughts as stated below. I would really like to hear from the
> framebuilders on the list to see if they agree with your assessment of the
> latest steel offerings. I do think that if one is light enough (under 165
> lbs.?), that many of these modern steels can be not only very durable but
> also be made to ride wonderfully, as well as being very lightweight. In
> particular, I have read some really good things about Columbus Foco tubing.
> Richard? Dale? Brian? Others?
> Richard (swayed by modern steel's), Rose (Toledo, Ohio)
> ----- Original Message -----
> From: Jerry Moos <moos@penn.com>
> To: Richard M. Sachs <richardsachs@juno.com>
> Cc: <Hilary.Stone@Tesco.net>; <mbikealive@earthlink.net>;
> <Classicrendezvous@bikelist.org>
> Sent: Tuesday, October 17, 2000 9:25 AM
> Subject: Re: [Classicrendezvous] Mexico vs Super (was: Colnago quality)
>
> > Heat-treated or no, I think 753 and other thin-walled tubeset are just too
> > thin. The simple fact may be that 531 or maybe 531SL along with Columbus
> > SL represented the best compromise between lightness and durability. What
> > we have seen since is tubes that are made too thin, then hardened in some
> > way to try to compensate for being too thin in the first place. I'm not
> > convinced that there has been any real metallurgical advance which has
> > really allowed a lower weight than 531 or Columbus SL without some
> > undesirable tradeoff. To the extent modern steel frames are significantly
> > lighter, it is less because of technical advances than because the public
> > is willing to accept them as a throway item like modern aluminum frames,
> to
> > be used 2 or 3 seasons, then discarded. It's perhaps not surprising that
> a
> > public which trades in automobiles every two or three years will no longer
> > expect that a bicycle last a lifetime. As with many things, British audax
> > bikes seem to represent a small island of sanity in this regard. I was
> > recently reading an online ad for a British audax bike (Thorn perhaps)
> > which stated that they used a Reynolds tubeset which, while a few ounces
> > heavier than some other tubesets, would produce a frame that would last
> > more than a few seasons. Such a statement seems rather bold today, as
> most
> > marketers seem to believe that a weight-obsessed public doesn't give a
> damn
> > about durability. With the proliferation of tubesets recently, I'm not
> > even sure which ones have adopted the thin wall throwaway approach and
> > which if any may have a wall thickness comparable to 531 or Columbus SL.
> > Tubing and frame ads don't typically list wall thickness. Anyone know of
> a
> > listing of wall thickness for most of the current tubesets?
> >
> > Regards,
> >
> > Jerry Moos