Old 03-14-21, 06:49 PM
Andrew R Stewart 
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Location: Rochester, NY
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Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Raleigh Pro, Trek Cycle Cross, Mongoose tomac ATB, GT Bravado ATB, JCP Folder

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Mixing thread specs between the two ends of a BB shell is pretty much unheard of, especially with a price point mass produced bike. Instead I suspect that there's some thread damage , rust, or initially poor factory chasing of the OEM threads. That plastic LH retainer ring (not really a cup at all) would mold it's self to whatever threading was there, steel being so much harder then plastic is. One possible solution is to do the thread chasing now. Better shops should have BB threading tools.

If one is doing a lot of this stuff (for themselves, friends or to flip bikes) then having a relationship with a LBS will have serious value at times. For info, advise or to do the operations that one can't do. Since we don't know where the OP is we can't give much help to a LBS location. But there's the phone and it only takes a few minutes to call around (assuming the OP has a phone and a local population that supports a LBS.)Andy
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