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  1. #1
    Senior Member JonathanGennick's Avatar
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    Dropout alignment question

    If the rear dropouts are misaligned by almost 1/4-inch, is that considered significant? I've a 29er frame that I'm about to toss, but I'm having a few second thoughts.

    When I measure everything out, it's as if the entire rear triangle has been bent left to the point where the left dropout is 1/4-inch to the left of where it should be. Is that sort of misalignment normal?

  2. #2
    Senior Member Nessism's Avatar
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    Rear end is 1/4" out of alignment and you are asking if this is normal? To answer this silly question: no, that is not normal.

    I've read that 2mm is the industry standard for rear dropout misalignment with a production bike. I'm sure this is a generalization but that number is often bantered about.
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

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  3. #3
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    That is huge. These days a good quality production frame will be aligned to a 10th of a millimeter or more. Good custom frames go even further, some builders claim thiers are within a few hundredths of a millimeter of perfect alignment.

  4. #4
    Senior Member JonathanGennick's Avatar
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    Nessisim, I intended no silly question. I'm just plagued by a bit of self-doubt. I crashed the frame once, and dropped it once -- about four feet onto concrete without the wheels in the dropouts. I'm certain the alignment problems are down to those two events. I don't in any way blame the manufacturer.

    The misalignment is fairly obvious to the naked eye. You can see it if you sight carefully. And putting a rear fender on the bike makes it painfully obvious, as the tire and fender end up in different planes.

    Knowing that things are out-of-whack really gnaws at me. There are also times when I'm convinced I can feel the effects when riding the bike ,especially when going fast. I've actually stripped the frame and had it in the garbage today when I became momentarily plagued by self-doubt. I'll probably just stick with my plan and toss it.

  5. #5
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    Don't toss it! What is the frame made of? If you bent it out of alignment it can be fixed, and probably fairly easily. Rear triangles are easy to put back into alignment, especially if the frame is steel. Do you have a long level or some kind of long stiff straight edge? Lay the frame on a table and rest a long straight edge on the head tube and the seat tube and have the end sticking out under the inside of the dropout. Measure the distance to the dropout. Flip the frame and do that on the otherside. Figure out which dropout needs to move in, and cold set it little by little. Keep flipping and measuring, and measure dropout spacing. You can do this in like 20 minutes. Don't toss the frame!

  6. #6
    Senior Member Road Fan's Avatar
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    If it's a steel frame, you should be able to get a good guy at a shop to do this for about $30. It's not a big job.

    If it's an aluminum frame, it could be dangerous to move the dropout a second time, due to the brittleness of aluminum.

  7. #7
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    No stupid questions. There are different kinds of misallignment. Are you saying the left DO is 1/4" outside of it's intended position, or so far bent out of wack it is 1/4" out of line with the right side dropout in the sense of being that much closer to the front wheel, or ground. That would be massive. 1/4" outside of the CL position is probably what every baggage handler strives for on a consistant basis, and depending on exactly how it got pooched to produce that result would not be a big deal to set right, even at home.

  8. #8
    Senior Member JonathanGennick's Avatar
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    Peterpan1, I'm going to try and remeasure later tonight, so that I can be absolutely certain of what I tell you. But the short answer is that I believe the left dropout is too for left, and that the right dropout is also too far left. The dropouts are also a tad too close together, but I'm not so worried about that aspect of things.

  9. #9
    Senior Member Road Fan's Avatar
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    Quote Originally Posted by JonathanGennick View Post
    Peterpan1, I'm going to try and remeasure later tonight, so that I can be absolutely certain of what I tell you. But the short answer is that I believe the left dropout is too for left, and that the right dropout is also too far left. The dropouts are also a tad too close together, but I'm not so worried about that aspect of things.
    Jonathan, it's probably more important to know what the frame material is than to exactly characterize the misalignment, at least if you're trying to plan a repair. For carbon and aluminum you really can't fix this, and I'm not really sure for Ti. Even if it's steel, I'd recommend getting a good frame technician to do the repair.

  10. #10
    Senior Member JonathanGennick's Avatar
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    Quote Originally Posted by Road Fan View Post
    ...For carbon and aluminum you really can't fix this, ...
    It's aluminum, for sure. Sounds like I was on the right track in thinking to dispose of the frame. I'd rather not take any risks from bending it back.

  11. #11
    Senior Member Road Fan's Avatar
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    Quote Originally Posted by JonathanGennick View Post
    It's aluminum, for sure. Sounds like I was on the right track in thinking to dispose of the frame. I'd rather not take any risks from bending it back.
    Despite what I said, we do have some real experts here, who might jump in and tell you I'm full of beans.

    I see you're in Michigan - where's Munising? I'm in Ann Arbor.

    Road Fan

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    You should recycle not send it to the dump. Seriously. Buy some vice with the procedes or donate to a cycling org.

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