Originally Posted by
lonesomesteve
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The serial number is from mid ‘77 and date codes on components are all ‘77, so most likely this was sold as a ‘78 model. The weird thing is that it matches almost exactly with the Semi-Pro in the ‘79 catalog on the Vintage Centurion website. There’s nothing I could find in the catalog that identifies the year, so it makes me think that maybe that catalog is incorrectly labeled as ‘79 when it’s really ‘78...
You do know that bicycles don't necessarily change every model year? As for the catalogue dating, the entry for the Sport DLX mentions a Shimano FE front derailleur, new Centeron rear derailleur and LS shift levers. None of these are in the 1978 model year catalogues, not even the mid-season May 1978 edition. Shimano introduced the FE front derailleurs, Centeron rear derailleurs and the Centeron compatible LS shift levers for the 1979 model year. So, the subject catalogue is no earlier than the 1979 model year.