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Old 05-21-07, 07:29 PM   #1
operator
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Which is the strongest type of fork construction

Jobst brandt mentions here: http://yarchive.net/bike/fork_failures.html

That sloped crowned forks like this:



fail more than non-sloped. Is there such a generalization that says all crowned forks are inherently less strong than say something like this:

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Old 05-21-07, 08:17 PM   #2
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He also says this: "Current unicrown forks with fork blades curves inward to the steertube
where they are welded is a crude heavy manufacturing shortcut using
far heavier fork blades that road bicycles used."

Unicrowns be fugly and that is that. He really prefers the old style externally lugged [flat] crown forks. Pretty in chrome, too.
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Old 05-21-07, 08:28 PM   #3
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Not that I have any scientific info to back it up, but assuming we're talking about fairly high quality stuff here, I would think unicrown forks, ugly as they are, are generally stronger than lugged crown forks. The tubes are fat, which makes for a strong, stiff fork. In the early days of mountain biking, lugged crown forks had a well deserved reputation for being more "compliant" than unicrown forks, because the fork blades would flex more for a more forgiving ride. That's good sometimes, but in terms of the strength of the fork, I think the flexiness is telling.

I've got a "double plate," lugged crown fork off of an early Shogun Prairie Breaker mountain bike. I think it's the coolest fork I've ever seen. These "double plate" lugged crown forks were supposed to be the strongest design for a lugged crown fork. They basically have two plates instead of one at the crown, one on top of the other with a gap between them. I think some of the early Bridgestone mtb's had this type of lugged crown fork for awhile.

As to whether a sloping crown like the one shown on the Raleigh Professional would be more prone to failure than a lugged crown fork without a sloping crown, I don't know-

Last edited by well biked; 06-30-07 at 08:01 PM.
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Old 05-21-07, 09:29 PM   #4
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Heh.. i was just thinking that no bike color would ever be called 'Blue Mink' today...
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Old 06-30-07, 07:53 PM   #5
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Quote:
Originally Posted by robo
Heh.. i was just thinking that no bike color would ever be called 'Blue Mink' today...
Do'nt go making fun of the Raleigh Professional now, that was a very popular color that they used for years.
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Old 07-01-07, 06:02 AM   #6
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I don't know but have you heard of any modern forks breaking at that weld? I've seen a lot that got bent back by a crash (lugged forks do that too) but no broken welds. I'm thinking that strong enough is strong enough.
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Old 07-01-07, 06:11 AM   #7
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Quote:
Originally Posted by Retro Grouch
I don't know but have you heard of any modern forks breaking at that weld? I've seen a lot that got bent back by a crash (lugged forks do that too) but no broken welds. I'm thinking that strong enough is strong enough.
For road bikes these days, the welded vs brazed argument is almost academic as nearly all forks are carbon. Low cost ones use carbon legs bonded to an Al crown with an Al or Cr-Mo steerer (sort of the current version of a brazed construction) while higher cost forks are all carbon.

Only the C&V folks have to consider what type of steel fork construction is superior in strength and/or appearance.
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