johndeverill wrote:
ultrazenith wrote:
I have the same one, it's a 1993 M Trax 400. The top and down tubes are commercially pure titanium, the rear triangle and fork are cromoly, and the head tube is aluminium. It originally came with an Altus A10 drivetrain, diacompe 986 and SS5 brakes, and Deore DX thumbshifters.
I doubt the frames are commercially pure titanium as they would end up being around the same weight as a steel frame and I can confirm my MT4 frame is nowhere near the weight of an equivalent 531 frame of the era. Willing to be proved wrong though and I'd love to know what thy actually used. It was TIMET tubing IIRC....could be wrong though.
I'm 100 % sure the Dynatechs and M Trax titanium frames all used commercially pure Ti, definitely something below the standard aerospace grades used in the premium Ti frames. Raleigh never stated in their brochures which grade of Ti was used, but employees of Raleigh have confirmed to us here that the Ti Tubes came from IMI and were CP grade.
My experience with the bonded titanium frames is that are not noticeably lighter than a top of the line cromo frame, but my MT4 with Ti main tubes, chainstays and dropouts, and 531 seat stays, definitely is.
The bonding process used in the early / mid 90s Dynatech frames is also supposed to allow lighter tubes by avoiding the need for butted tubes or the weakening effect due to welding. So you get to use lighter, cheaper to make plain gauge tubing, and glue them into a lightweight aluminium head tube.