The mixte version of a diamond frame model typically have the same specs. In this case, I suspect your bicycle is slightly older than 1979, as this is just about the time that many companies switched from 5 to 6 speed freewheels. The serial number should allow us to accurately date you bicycle.

SunTour's Powershifters utilize a ratchet mechanism to counteract the derailleur spring and decrease shifting force. The ratchet intervals are not designed to index with cog spacing. They are intended to work with 5 or 6 speed freewheels of any cog spacing. Over shifting and subsequent trimming is normal (to varying degrees) on friction shifting derailleur systems.

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