Originally Posted by
lonesomesteve
I really appreciate your vast knowledge on the history of these machines. So, maybe you can help with one other puzzling piece of data. There's also a '78 catalog on the Vintage Centurion site that shows a Semi Pro with very different components, different color options and different graphics. Maybe they changed the Semi-Pro in the middle of the usual model year cycle?
The subject catalogue mentions "Best Buy" accolades for 1975 & 1976 from a national consumer reports publication. Even if we assume they did a running change to the catalogue within the model year to take advantage of these commendations, it would still be no earlier than a 1976 model year catalogue. Conversely, based on the smaller product range, we know it pre-dates the 1979 model year catalogue. Consequently, it's 1976-1978 model years.
Fortunately, the Semi-Pro is a fairly popular model among C&V members. I've managed to collect data on all years from 1975-1981 inclusive. Examining the samples from the 1976-1978 model years, the only year with the black anodized components, as shown in the catalogue, are from the 1977 model year. Consequently, this would appear to be the model year.
1978 models manufactured in late 1977 exhibit the same traits as your bicycle and the 1979 catalogue, with the major changes from 1977 being down tube shifters, 700C wheels and a reversal to silver components.