T-Mar

Welcome to the forum. This is a very interesting bicycle. The serial number indcates 1977 or 1987 manufacture and late enough in the year that it could be a 1978 or 1988 model. The derailleur cable routing over the bottom bracket shell would be more typical of 1977/1978 but the logo style, presence of a set of bottle bosses and areo triple crankset point towards the latter.

The bicycle would appear to be an Asian market model based on the lamp bracket mounted on the right fork blade and the fork crown mounts for the front rack. As for its intended purpose, the fenders, rack and lighting system mounts suggest it's a city bicycle, intended for commuting, running errands and light exercise, primarily in urban regions, while the components are indicative of an entry level model.

I'm not sure if the handlebars and saddle are original. Brake safety levers had largely fallen out of use by this time and it was more common to see this style of bicycle with flat handleabrs and less racy saddle, at least in North America

Most interesting to me is the Light Action Positron derailleur system. To the best of my knowledge, we never saw these in North America. Shimano introduced Light Action for the 1984 model year but I thought Positron was replaced by SIS in the late 1980s, with Light Action receiving SIS as early as 1986. Yet the rear derailleur has a blind P-pivot, which Shimano didn't introduce on other derailleurs until 1987. To this end, I'd be very interested in knowing the derailleur date codes, which should be located on the back of inside parellogram arm for the rear derailleur and the back of the inside cage plate for the front derailleur. The format is a double letter (see attached example). Selected photo assist...