Originally Posted by
bikemig
I thought the whole point of using higher grade tubing is that you get could the same strength at a lower weight? I also suspect that decision to use 3 main tubes 531 and/or columbus tretubi was a good marketing tool (since the main triangle was made of a high grade steel) and a way of making the bike less expensive.
Not knocking tretubi or R531 main triangle bikes as many great riding bikes were made this way. One of my favorite bikes was a Pug PKN 10 which had a Reynolds 531 main triangle and I believe high tensile steel fork and rear triangle.
I really don't know, so I'm more "supposing" more than anything...
My understanding is your premium tubesets- 531c and Columbus SL were strong- but lacked the strength from mass- So in the case of specialized touring and 'heavy duty' sets, that extra strength and mass of the 501 or 4130 was preferred over the springyness of the lighter tubes. Think of the big knock on the 720- that it's too flexy. You're not getting that from the 620 or something like the Passage with that long wheelbase but with CrMo in the stays.
I do think towards the mid 80s there was as much of a price consideration- in getting mid-grade frames with a 531 sticker on them. I don't know if that helped as far as moving more product or made 531 less exclusive...