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Old 09-04-06, 02:28 PM   #1
godwit
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Aheadset keeps loosening

Help! I had a Surly LHT built up in March, it is equipped with a AheadSet SAS 1-1/8" thdls headset which seems to get loose often. When I squeeze the front brake and try to push the bike forward I don't get much movement, however when I go over bumps on my commute I hear the tell-tale hollow sounding tunk of a loose headset. Here's what I did : First I loosened the screws holding the stem on, then I tightened the screw on the top of the headset about 1/2 a turn. This seemed to solve the problem, however I need to do this once or twice a month. Am I not tightening the headset enough? How will I know if I tighten it too much? I have 1 and 1/2 inches of spacers installed also, could that affect the headset? I'm not too mechanically inclined but I'm learning. Any advice for me?

Mike
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Old 09-04-06, 02:52 PM   #2
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The proper adjustment of any cup-and-cone bearing (e.g. a headset, hub, BB, or pedal bearing) is: no wobble, and as little friction as possible.

It sounds like your headset is a bit too loose. You should figure out how tight you can make it without feeling any friction (resistance to rotating it), and then back off maybe 1/8 turn.

Make sure you get the stem bolts very tight! You have a steel fork, so no worries about overtightening them. Loose stem bolts are the only thing I can think of that would be causing the headset to loosen...
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Old 09-04-06, 03:22 PM   #3
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Follow Moxfyre's Parktool link for step-by-step instructions with photos.

Bob
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Old 09-04-06, 04:03 PM   #4
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What you are doing seems right. Essentially loosening the stem pinch bolts, operating the vertical adjusting bolt, tightening the stem pinch bolts. Park's site regarding headsets: http://www.parktool.com/repair/readhowto.asp?id=65

I've been using threadless for >8 years (off-road) and never had one loosen on me. Moxfrye's suggestion of making sure the stem pinch bolts are tight is probably the best advice, see attached for Park's installation torque recommendations: http://www.parktool.com/repair/readhowto.asp?id=88 The values don't seem high (~10ft-lb or less), but if you are using a hex socket (Allen) wrench that fits in your palm, it may not give enough leverage

The other possibility is the cups of the headset were not fully pressed into the head tube, and everytime you hit a bump, the cups seat a little more. Conceivable, it will eventually seat. See the first article above regarding proper cup installation and to look for a gap that indicated incomplete seating.

Finally, make sure the interface where the stem clamps onto the steer tube is clean and dry. Perhaps you have some grease in the area which reduces the desired friction. The installer could have inadvertently put grease in the area.
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Old 09-05-06, 06:28 PM   #5
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Quote:
Originally Posted by MudPie
Finally, make sure the interface where the stem clamps onto the steer tube is clean and dry. Perhaps you have some grease in the area which reduces the desired friction. The installer could have inadvertently put grease in the area.
+ 1 to that. I have also put baby powder into a slippery stem before, after cleaning it out, and that stops any slipage.
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Old 09-06-06, 01:16 PM   #6
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Put everything in place and remove the top cap. Check to ensure there's at least 3 mm (4-5 mm is best) between the top of the stem and the steerer tube. If there's not, remove the stem and add the appropriate width spacer and them reassemble and adjust. If there's not a sufficient gap, the topcap is bottoming on the steerer before proper adjustment is achieved. This is the single most important check when diagnosing the problem you're describing.
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Old 09-06-06, 01:38 PM   #7
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Put everything in place and remove the top cap. Check to ensure there's at least 3 mm (4-5 mm is best) between the top of the stem and the steerer tube. If there's not, remove the stem and add the appropriate width spacer and them reassemble and adjust. If there's not a sufficient gap, the topcap is bottoming on the steerer before proper adjustment is achieved. This is the single most important check when diagnosing the problem you're describing.
Agreed, that would be the very first thing I'd check.
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