Originally Posted by 2-7offsuit
T-Mar, I looked, but I can't find any markings on the bottom bracket. Maybe I'm not even looking in the right place. The dropouts say "Suntour GS" so you're right there. Did any Japanese brands use Falk tubing? or could the "Falk SL 66" sticker mean something else?
While looking around on google I did find one bike that looks pretty similar...
http://www.fixedgeargallery.com/2005...ky.htm#image_2
Lack of markings on the cups would indicate English threading, assuming it's an SR cup to match the crankset. This, plus the SunTour dropouts make a Japanese origin far more likely than Italian.
The Falk tubing is still perplexing. Some of the better Japanese builders did use Italian tubing and in the early 1980s many of the top Lotus models used Columbus tubesets, but I have never run across a Miyata with an Italian tubeset.
Miyata, did make uncataloged models every so often and this could have been a special run for the customer, which would explain the different lugs, stay ends and tubing. Still, the only thing that matches Miyata is the serial number format, so I can't say conclusively that it is a Miyata.
Do the lugs or bottom bracket have any cut-outs? The top Miyata during this period had holes in the lugs (similar to Cinelli) and holes in the bottom bracket.