NukeouT

Im seeing it on a lot of the bikes listed in the Specialized archives...

Is M2 the same or does it relate to Carbon or Aluminum material?

also, whats the designation for Compact if M2 is Mid Compact?

Just trying to figure out how to write bike model names shorter or if I can omit this info and save it for the frameset description

Wingsprint

The "M2" refers to the tubing material, "M2 Metal Matrix Composite", an aluminum alloy with some ceramic mixed in. M2 was used in road and mountain bike frames for very short time.

Cant help with the compact question.

revchuck 

"Compact" and "mid-compact" refer to cranksets. Compact = 50/34, mid-compact = 52/36.

Andrew R Stewart 

I'm not at a Specialized shop any longer but IIRC M2 tubes were in use in the mid/late 1990s. It is a mix (not an alloy) of an alloy of AL and ceramic like material (we called it "beach sand"). The particles of the doping material would be trapped in between the "cells ' of the AL alloy. The particles would act much like wheel chocks do, preventing the "cells" of AL alloy from rolling around each other and making any cracks take twists and turns as the cracks propagate through the tube. The claims were a stiffer tube (all else being the same dimensionally) and greater fatigue resistance. In practice the results were less then wanted and the manufacturing process more costly. My understanding is that Specialized moved on from M2 tubing a long time ago.

As to cranks- "compact" and mid or sub "compact are marketing terms to try to suggest some sort of difference that can be claimed as "better". Again, back in the mid 1990s the drivetrains of ATBs were shrinking the tooth counts for both front and rear ends of the gear system. As 12 tooth rear cogs became common the front ring sizes could get as few as 42T (for the large ring) and not loose too much a high gear (not that an ATB ever needed a high gear when used off road). The inner rings of these cranks was often 22T. IIRC Sun Tour used the term "Micro Drive" to describe their tiny crankset. "Mid Drive" usually refers to an additional set of cogs (and mounting shaft/bearings) in between the crank set and the rear cogs. Think of a tandem, a recumbent or an adult trike. Andy.