Originally Posted by
Road Fan
Not gonna make it a big debate, but I've always thought the info in the Trek catalogs is somewhat ambiguous, and I think they allowed themselves the freedom to use any CrMo or similar which was available and suitable to satisfy the manufacturing process and stop the line as little as possible. We have to admit, 531 and CrMo are pretty similar, though not identical, and many non-Reynolds branded tubings are CrMo. We don't really know what was in the minds of the engineers and managers or what may have been written in engineering documents. We only know the words that were chosen for the consumer's information. Presumably those were written by marketing people. It's a lot more than you get with a lot of bike companies, but it still is not the hard technical requirements.
The whole crux of the matter is '"what is a 700 series frame?"
If a 600 series frame has the same attributes, then why is the 700 series frame more expensive?
531 tubing is branded (as you mentioned). Does it make sense that Trek gave away premium branded tubing for the cost of tubing "of some other origin?"
It doesn't matter what's in the minds of the engineers, managers or engineering documents- If a frame is advertised and being sold as having "X" tubing- it needs to have "X" tubing. It's not like subbing Z series components because Simplex was unavailable- this is the very foundation of the naming convention, thus the price point the bike is at.
For those not wishing to pore through the Vintage Trek catalogs- Any 700 series frame has a butted 531 main frame with 531 stays and fork. ANY 600 series frame has a butted 531 frame and stays and fork made from CrMo or Manganese alloy from sources like Ishiwata, Tange and Reynolds (but not 531). And for anyone wishing to pore thru the Trek catalogs- 531CS is a
tube set with a 531 frame and Reynolds CrMo stays and fork.