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Old 04-29-07, 11:15 AM   #1
zephyr16
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Is it possible for a headset to ovalize?

im thinking about getting a Olmo road frame to replace my Bianchi, and while its a killer frame and everything, theres a problem with the headtube. When you take the fork and turn it side to side without the wheel, you can really feel that at about a 45degree angle from straight ahead it starts to resist turning, on both sides. if you just let it go it snaps back to straight ahead. now, its owner says that he had to use slivers of aluminum can when he intalled the headset. ive never heard of an ovailzed headtube on a road bike, but is it possible. it has an italian threaded bb, so is it possible that the headtube is italian somehow as well?
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Old 04-29-07, 11:59 AM   #2
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Originally Posted by zephyr16
im thinking about getting a Olmo road frame to replace my Bianchi, and while its a killer frame and everything, theres a problem with the headtube. When you take the fork and turn it side to side without the wheel, you can really feel that at about a 45degree angle from straight ahead it starts to resist turning, on both sides. if you just let it go it snaps back to straight ahead. now, its owner says that he had to use slivers of aluminum can when he intalled the headset. ive never heard of an ovailzed headtube on a road bike, but is it possible. it has an italian threaded bb, so is it possible that the headtube is italian somehow as well?
The difference between Italian and ISO headsets is trivial, and in any case it only applies to the threaded parts.

The symptom you describe is most often caused by a bent steerer, and should raise a MAJOR red flag in evaluating a used frameset for possible purchase.

Headsets are quite rigid, but head _tubes_ do sometimes get ovalized.

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Old 04-29-07, 12:03 PM   #3
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Originally Posted by zephyr16
(snip) ive never heard of an ovailzed headtube on a road bike, but is it possible. it has an italian threaded bb, so is it possible that the headtube is italian somehow as well?
And an Italian HT is oval????? There are Italian threaded forks, but it has nothing to do with HT shape, and you can use standard headsets on them. Maybe the previous owner tried to install JIS cups (0.2mm smaller) and had to shim, and his partial circle shims ovalized the cups.

edit: I like sheldons bent steerer
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Old 04-29-07, 01:22 PM   #4
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Maybe the previous owner tried to install JIS cups (0.2mm smaller) and had to shim, and his partial circle shims ovalized the cups.
Yeah but that would only be the press fit into the frame itself, how would it ovalize the races? I can't see how that would ever be true on a threaded headset pressed cups.
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Old 04-29-07, 03:05 PM   #5
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Also ovalized headset-cups won't cause the symptoms you describe of being tight at 45-degrees each side. That's because they'll be pinching the cones on the sides at ANY position of the steering. ONLY in the case of ovalized cups AND ovalized cones AND both cups AND upper & lower cones with their major axes aligned straight ahead would you then get pinching. And the tightest pinching would be when it was turned 90-degrees.

I vote for the bent-steerer on the fork.
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Old 04-29-07, 07:33 PM   #6
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well, if it is only a bent steerer, then thats less of an issue. the fork is nothing special, i will probably reuse my old fork, which should have a long enough tube. on a semi related note, im planning on using a threaded fork and clamping a threadless stem half on and half off the threads. now, i would think that so long as about half of the stem is off the threads(below) and half on i should be ok, right?
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