Front end advice needed; recurring problem maddening!- Mtbr.com
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  1. #1
    HOV
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    Front end advice needed; recurring problem maddening!

    Here's the whole story Cliffs Notes:

    - Bought a Redline Monocog 29er frame & fork off Craiglist. Stock fork and supposedly new Aheadset were included. Frame was worn but in good condition.

    - I built the bike:

    Mavic TN719 wheels on XT hubs
    Thomson Elite stem
    Easton Monkey Lite XC carbon bars
    FSA Maximus cranks
    Surly 36t steel SS chainring
    Dimension 18t rear cog
    SRAM PC-1 chain
    Avid BB7's with 16mm in back and 203mm up front
    Avid Speed Dial 7 levers

    - I rode the bike. Sweet, sweet ride. Maybe the best frame I've ever ridden including some gucci titanium stuff I've owned.

    - Problem on the trail: the fork gets loose. For some reason, the headest preload tension gets slack over bumpy stuff and the steerer tube ends up a little loose in the headtube/headset. After ad nausem adjustments (yes, all involving torque wrenches) didn't work, I:

    -- Removed Aheadset (crappy steel captured bearing) and installed Cane Creek 40 (nice aluminum cartridge bearing) headset
    -- Tried a different stem
    -- Replaced star nut

    I have at least 3mm space between the top of the steerer tube and the top spacer. Everything is torqued to spec. I adjust the headset preload screw until everything is tight but fork still rotates freely, then I torque the stem bolts to spec, alternating between the two bolts and gradually dialing in the torque.

    When the system has been loosened by the trail, it feels as if one stem bolt is looser than the other and there's virtually no tension in the top preload adjuster screw. This is the case with the Thomson Elite stem I have on there now. When I had a Specialized stem on there, a similar outcome happened.

    Nothing I've tried has eliminated this problem. Your advice is much appreciated, as I'm not sure what to do now. Loc-tite on stem bolts maybe??!

  2. #2
    The need for singlespeed
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    Face the headtube?

  3. #3
    Dirty South Underdog
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    How much are you tightening the stem bolts? Maybe go a little tighter.
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  4. #4
    HOV
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    Quote Originally Posted by zaskaranddriver View Post
    Face the headtube?
    I should have done that before installing the new headset. I can see how non-parallel faces of the headtube may cause this problem. Good idea, I may make this my next step.

    Quote Originally Posted by Andrea138 View Post
    How much are you tightening the stem bolts? Maybe go a little tighter.
    When working on this problem at home, I've been using 4.5 N*m. But on the trail I've gone ahead and used German torque. Problem remains. If I were to go the loc-tite route, I'd probably bump it up to 5 N*m and see hwo that flies.

  5. #5
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    How odd. Sounds like you've done just about everything to try to solve this. Some things that come to mind include: check the crown race to ensure it's fully seated/properly installed, be sure the headset cups are fully seated, check frame for stress cracks or head tube ovalizing. You could wipe your steerer tube with alcohol and reinstall the stem using some of that carbon friction paste. Also, maybe use a sharpie marker to make some tick marks on the steerer near the stem to track any potential stem slippage. Good luck

  6. #6
    HOV
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    I considered head tube ovalizing as a potential issue. if that were the case, wouldn't it be impossible to get the thing dialed in to begin with? Seems like everything from headset installation to setting preload tension would be whacked out by an ovalized headtube.

  7. #7
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    I wish I had something to add, except that I have the same problem with my rigid Jabberwocky running the Niner carbon fork and a Cane Creek S3. I'm starting to wonder if there's a beefier headset design that would work better with the longer suspension-corrected 29er rigid forks.

  8. #8
    HOV
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    http://forums.mtbr.com/singlespeed/h...se-507339.html

    Well, this thread revealed that I'm not alone. I suppose I'll give that Sette headlock gizmo a try.

    One thing I noticed was that the tension I put on the star nut never seems to get TOO tight like on most other headsets I've adjusted. Usually there's a point when you KNOW the headset's in the "too tight" zone; screw friction goes up exponentially in about 1/8 of a turn of the SFN.

    With my Redline adjustments, I never seem to reach that point. It just seems to get tight enough but never too tight. And I know I pulled out the old star nut a little on the trail one time, which is why I replaced it.

    This is a solid lead, definitely cheap and easy. I'm going to give the Sette headlock a try, see what happens.

  9. #9
    openwound
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    How much space is there between where the top cap rests (whether on a spacer or on top of the stem) and the top of the fork? The reason I ask is because if, for example, the end of your fork is dead even with the top of your stem and you're putting the top cap on there without a spacer, your top cap will bottom out against the stem. It can feel as if you're adjusting the tension correctly but will come loose in no time. There should be a gap of a good four or five millimeters between the highest element (spacer or top of stem) and the top of the fork in order for you to be able to adjust the tension.

    If that's not it, then, as has been suggested look into facing the head tube.
    -- let's ride

  10. #10
    HOV
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    I'm getting confused between my bikes trying to remember how much space each one has, but I always try to allow some space to compress the spacer stack and pull everything together. I think it has at least 3mm of space right now.

  11. #11
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    Quote Originally Posted by HOV View Post
    I'm getting confused between my bikes trying to remember how much space each one has, but I always try to allow some space to compress the spacer stack and pull everything together. I think it has at least 3mm of space right now.
    I believe Thomson recommends a 5mm spacer on top of your stem plus the 3mm for top cap steer tube interference. Also, I believe the torque spec is 5.5nm.

    They have instructions on the page.

    Bike Thomson: Elite X4

  12. #12
    empty beer member
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    I had the same issue with a steel Monocog fork and Thomson Elite stem (not the X4). I replaced the stem with a Chromag Ranger and all my problems were solved. I figured that the pinch clamp of the stem couldn't bite hard enough on to the steel steer tube of the fork. If you have a spare stem or can pull one off of another bike to test on the Monocog it will at least eliminate the stem at the culprit.
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  13. #13
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    Get your stem all dirty when you are installing it.. Or, better yet, use a

    azonic headlock or similiar device.

    I had the same issue on my Santa Cruz Heckler + Thomson. I tried three different headsets. Finally worked after I got the stem gritty. Hasn't slipped in the months since.
    Last edited by MrBaker; 06-18-2012 at 09:23 PM.

  14. #14
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    Quote Originally Posted by MrBaker View Post
    Get your stem all dirty when you are installing it.. Or, better yet, use a

    azonic headlock or similiar device.

    I had the same issue on my Santa Cruz Heckler + Thomson. I tried three different headsets. Finally worked after I got the stem gritty. Hasn't slipped in the months since.
    This is so simple yet ingenues, just add a little friction. And we're greasing everything up.

  15. #15
    Monkey Junkie
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    I had very similar issues with my old MC flight. A major factor was that the steerer tube was cut too short for the stem to adequately hold everything into place (which obviously isn't an issue for you). However, another problem was that the star nut that came with the stock headset was made for an aluminum steerer tube and was slipping. The shop got me one that was made for a steel steerer and it helped. A headlock was also a viable option, but the bike got stolen so I was never able to try it.

  16. #16
    CB2
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    Could the star nut be slipping as you say you never seem to be able to get it too tight?

    Did you replace the fork race when you swapped headsets?

  17. #17
    nothing to see here
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    Some other suggestions if I may...

    Is the stem cap carbon? Flexy?

    Try locktite on the star nut bolt.

    Try marking the stem cap (and bolt) with tape or something removable, to see if the bolt is undoing itself whilst you're riding.
    I see hills.

    I want to climb them.

  18. #18
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    The top cap and bolt are really only for setting installing the stem to take up the play in the headset. The real holding power comes from the stem bolts. The problem is somewhere else.

  19. #19
    HOV
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    Quote Originally Posted by Oliver View Post
    I believe Thomson recommends a 5mm spacer on top of your stem plus the 3mm for top cap steer tube interference. Also, I believe the torque spec is 5.5nm.

    They have instructions on the page.

    Bike Thomson: Elite X4
    Thank you. I actually did add another spacer yesterday, just to be safe (before I read your post) and I will tighten it down to 5.5N*m.

    Quote Originally Posted by WrecklessREX View Post
    I had the same issue with a steel Monocog fork and Thomson Elite stem (not the X4). I replaced the stem with a Chromag Ranger and all my problems were solved. I figured that the pinch clamp of the stem couldn't bite hard enough on to the steel steer tube of the fork. If you have a spare stem or can pull one off of another bike to test on the Monocog it will at least eliminate the stem at the culprit.
    I did - tried it with a Specialized Comp and the problem remained. But that may only mean that neither stem had enough bite for the fork. It could be that the steerer tube is deformed. I may try using another fork and see what happens. If another fork loosens, then it absolutely must be the headtube faces being not parallel.

    Quote Originally Posted by CB2 View Post
    Could the star nut be slipping as you say you never seem to be able to get it too tight?

    Did you replace the fork race when you swapped headsets?
    I thought the star nut was slipping, but I used my star nut installation tool to check the depth and it is exactly right.

    I did replace the crown race when I switched headsets. Finally bought the damn Park Tool crown race installer, as the $0.39 piece of PVC I was using earlier finally shattered on another install. I suppose the Park tool is worth the money....

    Quote Originally Posted by Stevob View Post
    Some other suggestions if I may...

    Is the stem cap carbon? Flexy?

    Try locktite on the star nut bolt.

    Try marking the stem cap (and bolt) with tape or something removable, to see if the bolt is undoing itself whilst you're riding.
    Stem cap is aluminum. Nice quality one IMO, came with the Cane Creek 40.

  20. #20
    Gigantic Hawk
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    With a marker, draw a mark on the inside of your steerer tube where the star nut is. This will allow you to easily see if the nut is moving north.

  21. #21
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    Another thing to check - be sure the top and bottom sealed bearings in the headset are indeed in the correct top and bottom cups. Just yesterday, my friend was mentioning that his headset wasn't quite right and wouldn't hold adjustment. Turns out the bearings were reversed. They looked VERY similar, but upon closer inspection some of the tapered/beveled portions of the sealed bearings were indeed not identical. Worth a try.

  22. #22
    HOV
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    ^^Yessss. That can be a maddening problem. On my last headset install I placed the bottom bearing cartridge in upside-down and it went from super loose to immovable in 1/8 of a rotation of the SFN tensioner screw.

    I checked the orientation of the bearings a few times on this one. The problem of loose fork was happening on the previous headset, which is in fact why I replaced the headset in the first place. I had high hopes that changing the headset would fix the problem, but it didn't.

  23. #23
    HOV
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    Well folks, the problem is solved.

    I think the first and most important step in fixing this was to set the stem with correct torque - 5.5 N*m as opposed to the 4.5 N*m I was using before. Thanks Oliver for that great tip.

    Second step was to put some blue loc-tite on the threads of the stem to make sure the bolts didn't back themselves out.

    These two steps seemed to fix the problem on my rigid fork, but then I switched forks to a Manitou Tower Pro. When the new fork came in, I went with the PricePoint brand head lock (Sette) and I'd have to say that I'm never going to run a SFN again. I love that it doesn't put any wear on the steerer tube as does a SFN, and that you know once the headset is preloaded, it's not going anywhere. That's a nice way to isolate any future issues.

    Anyway, everything is squared away now and the new hardtail runs superduper. Thanks for all the brainpower spent to help out, you guys are awesome.

  24. #24
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    I know this is an old thread but I was having the same issue w/ my Flight and the stock rigid fork. After switching to a Thomson stem and having the same slipping issue I measured the steerer tube and it was not 1 1/8" as advertised. Contacted Redline and a new fork is on the way. Excellent customer service!

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