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  1. #1
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    Modifying 7005 aluminum bike frame seat stay part from full suspension bike.

    I have a 2008 Brodie Mettle FS xc mtb and I want to modify the seat stay to better accommodate a 650B rear wheel and tire. A 650B wheel and 2.25 Racing Ralph tire fits as is but is too close to ride comfidently without potential rubbing issues from flexing, rim warp/out of true or mud. Front Fox fork fits 650B no problem.

    If the axle location was moved back 1/2" or less, and/or other modifcations were made to the seat stay, it would most likely allow the bike to run 650B in the rear without concern of rubbing. The effective chain stay length is 16.73 so for a 26" bike it is not too long. Lengthening the cs length 1/2" won't make it any longer than what I have seen on many actual 650B bicycles, so I think this is worth a try. Also, the bb height wfter putting on 650B wheels would be similar to an actual 650B bicycle so again, it shouldn't be too out of wack, and since I am only modifying an extra removable replaceable part, it's not risking anything except money for the part and mod. The separate seat stay is only $100 ($125 with bearings) and if modifying the part is a disaster and/or is un-successful, it's only a loss of the part and money spent working on it. My bicycle remains intact.

    With this project in mind, can anybody recommend a place who does frame repair and custom modifications of the kind I want to do? I have found a few places on the net and I will continue to do research myself.

    thanks in advance for any info,

    Last edited by morkys; 11-13-2012 at 05:59 AM.

  2. #2
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    Anyone who does aluminum stuff (FTW/Spooky, Rock Lobster, 3d, etc) can do it, I'd imagine. You will not like the price they'll want to charge, though, I'm guessing.

    -Walt
    Waltworks Custom Bicycles
    Park City, UT USA
    www.waltworks.com
    waltworks.blogspot.com

  3. #3
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    Thanks. I will check into those. I found a promising place in VA and a local place I am going to look into. Prices for seat stays and replacing dropouts don't seem too bad, but I guess my specific custom mod work may be a bit more involved.

    This place looks good:

    Eagle One Bike Frame Repair LLC

    Says he used 7005 aluminum and seems to understand the welding.

    I sent in a form detailing my idea so hopefully I hear back.
    Last edited by morkys; 11-13-2012 at 10:22 AM.

  4. #4
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    I am starting to think that a simpler solution would be to modify the dropout somehow by having somebody make something bolt-on, or, replace and otherwise replicate the seat-stay using steel. Methinks expensive.

  5. #5
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    Here is what the right, drive side of the part looks like. Not my photo, I stole it from a guys for sale post, but he sold the bike. The bike is the same as mine.

    I think I could actually just have the dropout cut and re-welded, avoiding welding of the tubes. Anybody know what I mean? The part could be heat treated afterwards.
    Attached Thumbnails Attached Thumbnails Modifying 7005 aluminum bike frame seat stay part from full suspension bike.-brodie-mettle-drive-side-ss-dropout.jpg  


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