Specialized Z-21 rim width and appropriate tire size.- Mtbr.com
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  1. #1
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    Specialized Z-21 rim width and appropriate tire size.

    I'm in the process of restoring an old Rockhopper and I just purchased a used set of Specialized Z-21 rims with XT hubs and double butted spokes that supposedly came off a Stumpjumper. I have not worked with these specific rims before but I do see that they were original to many of the Specialized mountain bikes in the early-mid 90s.

    I am blown away at how narrow these rims are. Measuring with my digital caliper, I have the outer rim width at just shy of 20mm and the inner width rim at just shy of 15mm. That seems like a very narrow rim to put a 26x1.95 tire, or whatever was the stock tire size at the time. I know that people managed to stuff very large tires into very narrow rims back then, but this just seems like really pushing it! The two Rockhoppers I have of that vintage and the Trek 820 I just tore apart for a friend all had Mavic or Weinmann rims that had 17-19mm inner widths which seems more appropriate.

    Can anyone confirm that I am not crazy and these rims really are that narrow? If anyone owns an old Stumpy or Rockhopper that came with these rims, how is the fitment of the tires?

  2. #2
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    Quote Originally Posted by notroman View Post
    I'm in the process of restoring an old Rockhopper and I just purchased a used set of Specialized Z-21 rims with XT hubs and double butted spokes that supposedly came off a Stumpjumper. I have not worked with these specific rims before but I do see that they were original to many of the Specialized mountain bikes in the early-mid 90s.

    I am blown away at how narrow these rims are. Measuring with my digital caliper, I have the outer rim width at just shy of 20mm and the inner width rim at just shy of 15mm. That seems like a very narrow rim to put a 26x1.95 tire, or whatever was the stock tire size at the time. I know that people managed to stuff very large tires into very narrow rims back then, but this just seems like really pushing it! The two Rockhoppers I have of that vintage and the Trek 820 I just tore apart for a friend all had Mavic or Weinmann rims that had 17-19mm inner widths which seems more appropriate.

    Can anyone confirm that I am not crazy and these rims really are that narrow? If anyone owns an old Stumpy or Rockhopper that came with these rims, how is the fitment of the tires?

    You measurements are correct.

    Someone may correct me but I believe the model name z-21 refers to the rim with 21mm.

    As with all rims there are some tires that fit snugger than others. My experience with Specialized rims is that they were fairly easy to work with. I had no trouble mounting tires from Conti Grand Prix 26x1" to Specialized GC Extreme 26x2.5".
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  3. #3
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    Great, thanks for the confirmation. I wanted to be sure before I ordered tires.

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