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  1. #1
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    derailleur adjustment issue (replaceable hanger flex?)

    So I just built up my first road frame, and everything went smoothly until I tried adjusting the rear derailleur. Even with the derailleur cable disconnected and the high stop screw loosened all the way, I cannot get the derailleur to move the chain into the highest gear. Attaching the cable didn't help.

    Looking into the problem, I found that clamping the rear wheel skewer (with moderate clamping force) makes the hanger flex such that the bottom of the derailleur cage moves inward by 4-5 mm. I *think* this is probably why the derailleur can't reach the highest gear.

    (Even if it could reach the highest gear and I got it adjusted perfectly, since the amount of flex is dependent on clamping pressure it could mess up my shifting if I changed a tire and put the wheel back on with different clamping pressure.)

    The replaceable hanger is molded (not machined) and has rounded sides, which creates a gap between the hanger and the frame near the axle. I think clamping down on the skewer closes that gap, which rotates the hanger.

    I've contacted the frame manufacturer, but has anyone else run into this problem? Or am I barking up the wrong tree? Any suggestions would be appreciated. (Frame is a 2010 Lynskey R230).

    There's a web site specializing in aftermarket hangers that are CNC machined, but it doesn't look like they have an exact match.

    Thanks.
    Last edited by jayp410; 08-12-10 at 11:38 PM.

  2. #2
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    What is the rear dropout spacing on your frame? (It should be 130mm.) Are you using older ≤7 speed wheels?

  3. #3
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    Frame spacing is 130 mm, and I'm using 10-speed wheels. Dura Ace 7800 12-27 cassette. Rear derailleur is DA 7800 SS. The issue is that the derailleur can't be adjusted to reach the 12 tooth sprocket.

    I think the issue is that the hanger is molded (not machined) so the face of the hanger is not very flat...it curves in (becomes thinner) all around the axle so it does not have a good contact surface against the frame (which IS flat) (see pictures), so this creates a gap. When clamping down on the skewer, it's squeezing this gap which is making the hanger and derailleur move inward towards the wheel.



  4. #4
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    it's not you, it's crappy construction. You have a few ways to deal with it.

    1-If the frame's surface there is truly flat, consider laying a sheet of emory cloth on a table and rubbing the hanger back and forth to sand it's mating surface flat.

    2-If the frame's surface isn't flat, bed the hanger in body filler, and allow it to cure before installing the wheel.

    3- leave it as is and tighten it as best you can.

    No matter how you deal with it, you still should always check the hanger alignment with a wheel in and tightened. Actually, other than tightening it to riding standard, you don't have a choice because you need the wheel as the reference for the alignment gauge.

    BTW- before doing this, try to figure how to get it so it's inner surface lines up with the inside of the dropout. You need to establish this position because the RD's travel range is designed around the assumption that it's mounted 6-8mm outside of the end of the right axle face (thickness of dropouts).
    Last edited by FBinNY; 08-13-10 at 09:57 AM.
    FB
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  5. #5
    coprolite fietsbob's Avatar
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    Is the tab a steel part , [?]
    +1 , Has the frame been checked for derailleur tab alignment?

    Its not automatic, it may need some tweaking..

    You jumped into the deep end of the pool with Ti Frame and the latest parts.

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    Quote Originally Posted by FBinNY View Post
    it's not you, it's crappy construction. You have a few ways to deal with it.

    1-If the frame's surface there is truly flat, consider laying a sheet of emory cloth on a table and rubbing the hanger back and forth to sand it's mating surface flat.

    2-If the frame's surface isn't flat, bed the hanger in body filler, and allow it to cure before installing the wheel.

    3- leave it as is and tighten it as best you can.

    No matter how you deal with it, you still should always check the hanger alignment with a wheel in and tightened. Actually, other than tightening it to riding standard, you don't have a choice because you need the wheel as the reference for the alignment gauge.

    BTW- before doing this, try to figure how to get it so it's inner surface lines up with the inside of the dropout. You need to establish this position because the RD's travel range is designed around the assumption that it's mounted 6-8mm outside of the end of the right axle face (thickness of dropouts).
    Your option #2 is probably the best.... I don't think I could sand / file the hanger flat by hand (too much material and too difficult to keep it flat while sanding), and leaving it alone is also not an option since the bike is currently not ridable.

    I had a similar idea, but was thinking about using epoxy (and maybe fiberglass cloth) to mold a shim. It would probably be a little messy but would hopefully get the job done.

    Good advice on the measurement of 6-8 mm outside of the right axle face.... I'll have to be careful about that.

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    Quote Originally Posted by fietsbob View Post
    Is the tab a steel part , [?]
    +1 , Has the frame been checked for derailleur tab alignment?

    Its not automatic, it may need some tweaking..

    You jumped into the deep end of the pool with Ti Frame and the latest parts.
    The tab is aluminum.... I'm not sure about checking it for alignment - it looks pretty good to me (flush with the inner face of the frame) when the wheel is not in there. It's more the clamping pressure of the wheel skewer that is the problem - it makes the hanger rotate.

    Yes I did jump in the deep end of the pool... first real road bike, first frame build, $2K frame.

    The most frustrating thing is that the bike is almost completely built and looks awesome, and feels like it's going to ride great. So close to biking happiness, yet so far....

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    hanger alignment is done with a 50 or so dollar tool. it is done with the wheel in place and clamped.

  9. #9
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    +1 on the emory cloth and sanding. If available a sheet of glass or maybe a granite counter top will give you a nice flat surface to do it.

    Or better yet contact the $2K frame maker (or seller) and tell them to supply you a new FLAT $10 hanger at their expense.
    '68 Raleigh Sprite, '02 Raleigh C500, '84 Raleigh Gran Prix, '91 Trek 400

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    I agree that the hanger looks a little sloppily made for such an expensive bike, but if I were you I'd have a shop with a hanger allignment tool check to see if it is bent. It's not at all uncommon for the hangers on brand new bikes or frames to have been tweaked during shipping.

    Have you recieved a response from Lynsky yet?

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    Quote Originally Posted by silver_ghost View Post
    I agree that the hanger looks a little sloppily made for such an expensive bike, but if I were you I'd have a shop with a hanger allignment tool check to see if it is bent. It's not at all uncommon for the hangers on brand new bikes or frames to have been tweaked during shipping.

    Have you recieved a response from Lynsky yet?

    Lynskey is talking with me, although I'm not sure what they plan to do about it. I hear they redesigned the hangers for 2010 but I admit it would seem odd if I were the first person to have a problem even this year....presumably they've sold bikes to other people this year who haven't had a problem.

    I will take it to the local shop and have them check for alignment, and see what they have to say. Maybe I'm misdiagnosing it or something.

    I also found a web site that specializes in aftermarket hangers, and ordered one from them. They say it's compatible shape and flat...we'll see, but I'm not holding my breath.

    If none of the above works, I may try the auto body filler.

    Thanks everyone for all of the responses.

  12. #12
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    As I said in the my earlier post, the first issue is whether it's the hanger or the mating area on the frame that isn't flat. If the hanger pocket in the frame isn't flat, a new hanger won't magically solve anything.

    Though the hanger should, and as a practical matter must be aligned with the wheel on (the wheel's the reference), that compensates for, but doesn't actually fix the problem of poor fit. Even on a frame costing a small fraction of this one, I'd expect the hanger to pocket flat, and not move when the wheel is tightened.
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    Quote Originally Posted by FBinNY View Post
    As I said in the my earlier post, the first issue is whether it's the hanger or the mating area on the frame that isn't flat. If the hanger pocket in the frame isn't flat, a new hanger won't magically solve anything.

    Though the hanger should, and as a practical matter must be aligned with the wheel on (the wheel's the reference), that compensates for, but doesn't actually fix the problem of poor fit. Even on a frame costing a small fraction of this one, I'd expect the hanger to pocket flat, and not move when the wheel is tightened.
    While I haven't measured or checked the titanium hanger pocket with tools, visually it looks dead flat...it's CNC machined with impressive precision. The edges look square (90 degrees). I would be completely shocked if the frame itself is the problem.

    The aluminum hanger on the other hand has obvious curvature on the mating face, so I suspect it's responsible for all of the gap in the picture.

    I may try filling the gap with auto body filler while waiting for the new hanger to arrive...it might save a week of waiting. The only thing is, it might be a pain to scrape that stuff off (although I hear a propane torch can be used to remove it).

  14. #14
    coprolite fietsbob's Avatar
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    Check with the frame manufacturer and ask if they have a stainless steel replacement derailleur hanger.

    FWIW JB Weld is aluminum filled epoxy, , maybe able to lay down a layer of plastic packing tape as a mold release on the Ti.
    and fill gaps with JB Weld file smooth and square shouldered.

  15. #15
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    Quote Originally Posted by jayp410 View Post
    While I haven't measured or checked the titanium hanger pocket with tools, visually it looks dead flat...it's CNC machined with impressive precision. The edges look square (90 degrees). I would be completely shocked if the frame itself is the problem.

    The aluminum hanger on the other hand has obvious curvature on the mating face, so I suspect it's responsible for all of the gap in the picture.

    I may try filling the gap with auto body filler while waiting for the new hanger to arrive...it might save a week of waiting. The only thing is, it might be a pain to scrape that stuff off (although I hear a propane torch can be used to remove it).
    Since the frame looks good, I'd go slow before risking turning a minor problem (bent replaceable part) worse, by possibly messing up the frame pocket. I'd either wait, or work on the hanger, since there's nothing to lose that way.

    Try the emory cloth. You'll be amazed at how fast it goes and it's easy to keep the part flat simply by pressing in the middle, and sanding with a circular motion. If you have a glass table top, work there, otherwise a kitchen counter is good enough for the job. Start with course grit, and finish with medium. You're not making it beautiful, only flat. And you don't have to get it totally flat, only establish a decent surface in the between and around the two mounting bolts. Later you can get a new hanger, get 2 one for immediate use and a second as a spare.

    If you decide to use filler, smear a film of grease in the frame pocket, then line it with a piece of stretch wrap with two holes punched. Also be sure to grease the two bolts and the thread of the plate so nothing will stick. Later most, if not all, the body filler should release nicely from the frame, and require only minor clean up if any.

    Be sure to let it set and cure completely before squaring up the hanger, lest you squeeze partly set filler out and have to start anew.

    BTW- you don't need a stainless hanger, the aluminum one is sufficiently strong and rigid for it's job. You just need a flat one, so wheel pressure doesn't move it.
    Last edited by FBinNY; 08-14-10 at 09:27 AM.
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    i still dont see what the big deal is here. secure the wheel and put the hanger alignment tool on or bring it to the shop and pay them to do it. bling bling expensive frame with a cheap cast hanger(they are almost all cast anyways). almost all hangers move to some degree when clamped. if properly aligned, the hanger will be aligned and move to the proper position when the wheel is clamped and secured in place. it is not too difficult to use the same clamping pressure, the hanger should move to the same spot for the most part unless you clamp it real loose. people who have disc brakes must clamp their wheels with the same pressure or the disc alignment is off. i align hangers all day on new bikes, mostly trek because the way they pack their bikes is pretty flawed

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    You're right that the hanger can be straightened with the wheel on and clamped tightly, and that might solve the RD problem.

    But there are other considerations. First the flexing puts the dropout out of plane and adds stress on the axle. Also, if the hanger sits at an angle, even if the derailleur mounting area is parallel it might be too far out or in, and beyond the RDs travel range for the cassette. Sanding it to establish better support and stability before squaring up the RD tab is a few minutes work and makes for a better job.
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    Just to follow up... I took it to the local shop and they aligned the hanger, and now it's ridable.

    When starting the thread I didn't know that the hangers often need alignment or that they could be fixed locally with an alignment tool. Thank you guys for enlightening me on that.

    It still does flex when clamping the wheel down, which I imagine could still be a problem if I take the wheel off to change a tire and then don't clamp down with exactly the same amount of pressure. So I did order the aftermarket hanger which will hopefully improve the flexing issue.

    Just for fun, here are some pics of the build:




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