Hey Elev12k,
Thank you for taking the time to post and shed some light on my mysterious Miyata! I looked through the 1991 catalog and I didn't see much that matched the bike I'm inquiring about... however, when I looked at the 1992 catalog again I came across the "Trailrunner" and that matches the frame details.
Do you suppose this is a Trailrunner? Your frame description in your reply was spot on and the Trailrunner seems to be what you described. You think given the neon green paint that it's a Japanese model, would that be a model not intended for export? Have you heard or do you know of other Japanes specific models?
I have a 1989/1990 Nishiki Alien that Richard Cunningham designed, the one with the elevated chainstays and the Tange Prestige tubing (I also have the previous year's Ariel that R.C. designed without the elevated chainstays)... how would you rank this Miyata as it stands up against the Alien? I ask because the Alien was $1,000.00, it was made in Japan, and is a great bike. Did the Miyata stack up against the Nishiki as far as cost and desirability? I was familiar with their road bikes back then but not their mountain bikes.
Thank you again for taking the time to help!
-D-
p.s. "Bombproof"... you've never heard of any frames coming apart?