Joined: Feb 2012
Posts: 19,354
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From: Rochester, NY
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
There's all kinds of reasons why a part might be replaced with another grade. As long as the functional specs are the same there's generally no reason to replace the current der. As maddog34 said the Deore is a few grades above the Acera. "Better" materials, nicer coatings/finishing, grams less weight are the usual changes. The higher grade components often work better longer and can have more of their intended performance level brought back with periodic maintenance when compared to the more basic grades.
Is there a reason why you are thinking of a replacement? Andy
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AndrewRStewart