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Old 10-06-09, 07:48 AM   #1
bg4533
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Adjusting headset on a damaged steerer tube.

A friend asked me to look at her bike because the headset wouldn't stay adjusted. Upon disassembly I found that something put a big cut and mangled some of the threads near the top of the 1" threaded steerer tube. Every time I try to tighten the locknut it only gets so tight and then gets loose again. The headset looks healthy and currently consists of the threaded race, 2 spacers and the locknut.

The bike is a fairly nice Bianchi with Columbus tubing, so I'd prefer to save the fork. What are my options to address this issue? How important is the locknut? Would adding a keyed spacer and lockring between the race and locknut keep things tight and safe? Should I resort to Loctite? Cutoff the top of the steerer tube and remove the spacers? Other ideas?
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Old 10-06-09, 09:03 AM   #2
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The locknut is essential so somehow you need to make it work. If you can add anything threaded between the top race and the locknut, why not just use the locknut?

I think your best approach is to cut off the damaged threads and remove what ever spacers you have in there to allow the locknut to thread on properly. Since it's obviously a quill stem, just raise the stem slightly to compensate for the shorter steerer or get a stem with a longer quill if that's needed.
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Old 10-06-09, 03:16 PM   #3
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This type of damage is usually a result of riding for a long time with a loose headset. The slop allows the threaded cup to wobble on the steer tube, eventually eroding the threads so they no longer engage the cup.

There are two options to fix this: first, replace the fork with one that has good threads. This is often the easiest way to deal with the problem. Second, particularly with high-end frames where a generic replacement fork would be inappropriate and an original equipment fork is unobtainable, you can have a shop or frame builder melt brass into the damaged area and cut new threads into the brass. This has saved many a fork over the years.
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Old 10-06-09, 09:53 PM   #4
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You maybe able to pull the fork and take it to a LBS and have the threads chased
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Old 10-07-09, 04:11 PM   #5
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Originally Posted by Bikewrench217 View Post
You maybe able to pull the fork and take it to a LBS and have the threads chased
If the part won't tighten in the manner the OP described, that means the threads are shot. No amount of chasing will fix that.
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Old 10-07-09, 06:53 PM   #6
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rivendell has your solution:
http://www.rivbike.com/products/list...product=30-016
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Old 10-07-09, 07:03 PM   #7
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Good idea, if you use it, let us know how well it works.
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Old 10-08-09, 02:44 AM   #8
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Could we try a new topnut first? Could we also get rid of any spacers that seperate the topnut from the rest of the rest of the headset in order to clear the ****ed up threads?
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Old 10-13-09, 07:11 AM   #9
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The locknut that was on the bike was very short and only engaged the top couple threads of the fork. I borrowed a locknut that was about twice as thick from another bike and was able to get the headset adjusted properly. Thanks for the suggestions.
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