This conversation is obviously getting over my head; but, I have seen a couple pics on this forum where the owners identified/dated their steel main tube Techniums before 1990; I simply do not have the energy to find them for the moment. BTW The OP only quotes catalogs of 1990, 1991, and 1992.
Roadbikereview has a thread where Dennis Bushnell; a technician for Raleigh USA; claims to have knowledge or built Techniums out of Reynolds 753 prior to his departure in 1988. This supports the ascertion that Techniums were mfg with main tubes from both aluminum and steel prior to 1990. It would be nice to verify this with actual catalogs from 1987-1989. Those are apparently harder to find than "hens teeth".
Dave, as the technition(sic) responsible for the Raleigh Technium =
bicycles I should be able to help. As far as I know Raleigh Technium =
frames were a bonded 3 tube affair with a brazed rear triangle(including =
the seat stays) In the process, the seat stays were brazed to the seat =
lug(steel) the chain stays were brazed to the BB and then head tube seat =
lug and BB assy were pressed into pre glued tubes. The last process was =
brazing the seat stay drop out joint. Many of these were brazed without =
any added flux(not my idea). Some of these frames were alu, some were =
steel(753) Some of the bikes that came out of the Raleigh factory were =
prototypes that I made and were never intended to be ridden but got out =
anyway. When I left((AT)1988 there were still some bonded bikes being made =
with rear triangles from Taiwan. At any rate you should be able to =
replace the DO as you would any other steel frame. I would be interested =
in finding out when your particular frame was made.
Dennis Bushnell
Here is the link to the thread:
Raleigh Technium?
I may be way off base; but I'm not willing to rule out any combination of Techniums prior to 1990; until the info is garnished from a published catalog, or straight from the "horses mouth" (Raleigh USA)
I'll leave it at that until I have more concrete information.
Best Regards
Rod
UPDATE: I'm home from work and the magnet test is as follows on my 1986 Technium 440: one piece investment cast head tube and lugs-
steel; seat stay/seat post/top tube lug-
steel; one piece investment cast bottom bracket housing/lugs-
steel; rear stays-
steel; forks-
steel; front and rear investment cast dropouts-
steel. The same frame is used for the 480 and 460; so I assume the magnet test would be identical....... but we see how assuming has gone lately, not well for me btw.