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  1. #1
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    Modifying a Rear Triangle

    I have a 9-0-7 fat bike with a 170 mm rear drop out. I want to modify the seat and chain stays where they meet the tire for more clearance. Is there a way to do this without torching out material and welding? Maybe some sort of compression? I only need to gain a few mm per side.

  2. #2
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    Don't "torch out" anything. I have no idea what else you're asking but the smoke wrench never belongs anywhere near a frame.

  3. #3
    Nemophilist
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    Hey;

    As long as the stays are not crimped to start with, I'd say it would be possible to crimp them a tad. The trick is to effect the inner wall of the tube without deforming the outer, or messing up the finish, and doing it on a frame that is already built and limits your access. How anyone would accomplish that is open to debate and creativity, but it seems it might be done.
    Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
    - John Hajny, a.k.a. TrailMaker

  4. #4
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    Quote Originally Posted by TrailMaker View Post
    Hey;

    As long as the stays are not crimped to start with, I'd say it would be possible to crimp them a tad. The trick is to effect the inner wall of the tube without deforming the outer, or messing up the finish, and doing it on a frame that is already built and limits your access. How anyone would accomplish that is open to debate and creativity, but it seems it might be done.
    I have absolutely -0- experience in frame building so I must ask, is there a standard tool for this type of thing? How would one proceed? I am not worried about the paint, I can certainly repaint the bike. The paint sucks any way, way too soft. Like I said I only need a few mm on each side.

  5. #5
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    If it is an aluminum frame I would recommend you leave it alone.

    On a steel frame, crimping after the build can be done with a block of wood and a C-Clamp. Place the block of wood on the outside of the frame where you don't want to crimp and then apply the C-Clamp. The idea is that the block of wood will spread out the load on the non crimp side and the C-Clamp will create the crimp on the crimp side. Shaping the wood block can help with this. You can also grind the C-Clamp down a little to create a crimp form for the other side. Doing this is harsh but a steel frame should be able to handle the abuse provided it is not already crimped. Don't try to crimp more then a couple of mm on each side.

    After crimping you may need to spread the rear triangle very slightly because it will pull in a little when you crimp the stays.
    Mark Farnsworth, Raleigh, NC
    http://farnsworthbikes.com

  6. #6
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    9-zero-7 is making all of their current frames out of aluminum. I don't if if they ever did any out of steel. Pretty much the only modification that can be made to an aluminum frame after it's been heat-treated is the paint job--with anything more involved it's easier (and cheaper) to build another frame from scratch.

    Either grit your teeth and run a smaller rear tire or sell the frame and order something custom. Losing $300 selling your frame is a lot less painful than losing $800 when you turn it into scrap.

  7. #7
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    Sounds like I am up a creek with this frame. They are coming out with a wider version next year but I am not that patient. There are two other companies that have a wider frame now. I prefer the 9-0-7 but I may have to jump ship.

    thanks for the help

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