Based on info in the link below, if the serial number starts QB it's likely a January 1988 frame, which supports LeonL's suggestion that it's a later colour scheme on the previous year frame.
I don't know if the other numbers denote a model. I haven't seen anywhere that they might but someone else will know better.
I should be getting a late 1980s Koga Miyata Ridgerunner frame myself so will report back when I get the serial number.
https://www.bikeforums.net/classic-vintage/1042901-asian-serial-number-guide.html
I don't know if the other numbers denote a model. I haven't seen anywhere that they might but someone else will know better.
I should be getting a late 1980s Koga Miyata Ridgerunner frame myself so will report back when I get the serial number.
https://www.bikeforums.net/classic-vintage/1042901-asian-serial-number-guide.html