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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

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Old 04-27-06, 05:15 PM   #1
~stella
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elliptical headset dilemma (shimming)

i bought a used steel track frame with a headset installed a few months back. the ritchy logic threaded headset was in good shape so i decided there was no reason to upgrade it. after about two months it started giving me some trouble and would never stay when i would tighten it. i decided it was time for an upgrade.

i chose a campagnolo chorus headset and brought my bike to my local bike shop to have them install it. upon removing the ritchey headset, we noticed two small shims cut from a soda can fall to the ground. these shims had been keeping the bottom headset cup in place, since the bottom of the headtube had become slightly elliptical with use. is this at all common? has anyone had this happen to them?

we enventually installed the campagnolo headset using two new shims that we made from a can. the headset seems to be in securely, is this a dangerous approach? is my frame doomed or is there a permanent fix to this problem?

Last edited by ~stella; 04-27-06 at 05:57 PM.
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Old 04-27-06, 05:20 PM   #2
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i would assume that it would be alright, since the crown race will be putting pressure on it. as long as the bottom cup is shimmed securely, i can't imagine that this would be a problem.
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Old 04-27-06, 05:27 PM   #3
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sounds like your frame was crashed. ovalized headtubes happen.
beer can shims are a quick fix.
locktite (green?) or JB-weld should work too.
or a chris king steelset headset is sometimes the answer in MTB-applications.
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Old 04-27-06, 08:36 PM   #4
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Quote:
Originally Posted by baxtefer
sounds like your frame was crashed. ovalized headtubes happen.
beer can shims are a quick fix.
locktite (green?) or JB-weld should work too.
or a chris king steelset headset is sometimes the answer in MTB-applications.

JB-weld is probably a better solution then the beer cans. I would worry about their bering a minute amount of play with them and furhter ovalizing the headtube.
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Old 04-27-06, 09:01 PM   #5
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Quote:
Originally Posted by baxtefer
sounds like your frame was crashed. ovalized headtubes happen.
i don't think it was crashed, because the radius is longer front and back than side to side. normally if a frame was crashed it would be frontal impact right?

i suppose that isn't the issue though. haha.
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Old 04-27-06, 09:31 PM   #6
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how was the frame joined? sometimes if too much heat is used at the joint it can deform the tubes slightly.
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Old 04-27-06, 10:11 PM   #7
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Quote:
Originally Posted by ~stella
i don't think it was crashed, because the radius is longer front and back than side to side. normally if a frame was crashed it would be frontal impact right?

i suppose that isn't the issue though. haha.

headtubes ovalize by streching not compressing. A frontal impact would lead to a larger radius longitudinaly then laterally as you described. Really it could ovalize either way in a crash but front/back is probably most common. I once ovalized one by hitting a pothole so its entirely possible that the frame was never actually "crashed".
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Old 04-28-06, 07:00 AM   #8
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I took the original headset off of my 1970s Sekine frame and replaced it with an Ultegra sealed headset. We had to face the surface on the fork where the crown race seats because the fork was set up for an older standard that was a slightly larger size. Jim at the HC had the tools for the job, but I think we went a tad too far down, since the crown race would fit nicely but couldn't be driven firmly into place (it would remain loose). He explained the beer can shim trick to me and said that he's done it a few times in the past when something like this happens, but we decided to try just assembling the headset as-is to see how it felt, since the crown race seemed to sit snugly in place as long as there was some downwards pressure on it.

Over the past few days (it's been a few hundred miles now), I'm noticing a distinct pop when I go over the right sized bumps/cracks in the road at the right speeds. I'm almost certain that it is the crown race rattling around slightly. I will be taking it apart sometime soon to address the issue, and I think JB weld sounds like the best solution to me. Pack it in there like epoxy to fill in the voids and eliminate the room for the race to bounce around once it has cured.

In short, the beer can trick is widely used when there isn't a perfect fit with the crown race and it seems to work fine, but JB weld might be better. Jim recommends using triangular pieces of can so you can slide them in further to get more shimming action. Once you get it about right, drive the race on and cut ot tear the protruding bits of aluminum off. Two shims sounds better than one to me.
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Old 04-28-06, 07:01 AM   #9
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am i making the problem worse by riding on this frame though? is this at all dangerous??
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Old 04-28-06, 07:04 AM   #10
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You may want to hold off on any bumpy riding until you can address the matter. I don't think light riding will be a problem, but bumps, potholes, curbs, and hard front braking (combined no less) would not be the greatest plan. Smooth bike trails and freshly paved roads shouldn't do any more damage in the mean time though. It takes quite a bit of force to outright bend steel, but you can robably erode the crown race or steerer tube if they rattle against eachother for a long time.
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Old 04-28-06, 07:39 AM   #11
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Quote:
Originally Posted by baxtefer
sounds like your frame was crashed. ovalized headtubes happen.
beer can shims are a quick fix.
locktite (green?) or JB-weld should work too.
or a chris king steelset headset is sometimes the answer in MTB-applications.
Locktite makes a couple of products for dealing with exactly this problem in automotive applications.
Go to Loctite.com and search under Automotive | Cylindrical Assemblies (Retaining)
641 is good where the tolerance isn't too far off.
620 is great where things are pretty loose, but it takes 450 degrees of heat to make it let go.
(Those are the two I've had the most experience with in car and motorcycle racing.)

The cool part is that these are all anearobic. They stay liquid as long as they're exposed to air. Close them up in a small confined space (like the small gap between a bearing cup and an ovalled headset) and they set up solid. Clean-up is easy.

Poke around a bit and you'll find something that will do the job. You'll be able to get it at any auto-parts store.

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