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Aluminum forks: general strength, and suitability for use with front racks?

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Aluminum forks: general strength, and suitability for use with front racks?

Old 02-07-13, 05:09 AM
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Catte
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Aluminum forks: general strength, and suitability for use with front racks?

Hello, all. Had a hard time deciding which forum this should go in, so I apologize in advance if this wasn't the ideal choice.

I was mindlessly clicking around Velo Orange's inventory yesterday. While looking at their various rack offerings I noticed this:

https://store.velo-orange.com/index.p...stainless.html

In the description, they warn "Not recommended for carbon or aluminum forks."

The carbon disclaimer, I can understand, as I'm under the impression that carbon fiber has a tendency to break when receiving lateral loads that the designers did not anticipate.

But, aluminum? As far as I know, aluminum isn't so finicky, and alu forks should be just as strong as steel forks, right?

So long as the rack is installed properly (torqued down so it isn't allowed to wiggle, yet not torqued so tight as to crush the fork tube) I would think it would be a safe combination.

What do you guys think? Is this just paranoia (an potential "steel is real" snobbery) on VO's part? Or is it a fair and wise assessment of some inherent limitation in aluminum forks that I don't fully appreciate or comprehend?
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Old 02-07-13, 05:57 AM
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Good question.

Aluminium is no less isotropic than steel AFAIK, so I think you're right to doubt the kybosh.

On the other hand, it prolly depends how much you're gonna load up the rack.
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Old 02-07-13, 05:59 AM
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I think their target demo particularly enjoys believing imaginary nonsense about both aluminum and CF.
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Old 02-07-13, 06:19 AM
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Aluminium threads are weaker than steel ones. I would prefer a looped front rack that connects both sides. This rack has 2-point fixing each side and may be vulnerable to swaying which can eat away at the thread.
My everyday commuter bike has an Al fork which is doing just fine.
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Old 02-07-13, 09:40 AM
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If there is a concern regarding the strength of the threads, Heli-Coil inserts can be installed which will provide stainless steel threads which are stronger and more wear-resistant than the original aluminum. This is a standard procedure in the areospace industry for threaded holes in aluminum. The tooling is a little costly for a single job but a good machine shop should be able to do the work economically.
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Old 02-07-13, 09:53 AM
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If you need a rack and are unwilling to put a steel fork on, for loaded touring,
I suggest Old Man Mountain the mounting point is the QR axle skewer and the V brake boss end.

that hoopless rack needs the secure mounting of a reinforced hole thru the center of the fork blade
and a strut on rack bracing both sides , of the mount at Mid fork.

That just uses U bolts.. Keep Shopping .

control of the bike is effected by how well yhe load on the fork mounted rack is secured..

Last edited by fietsbob; 02-07-13 at 09:57 AM.
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Old 02-07-13, 10:07 AM
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Fietsbob is correct, the rack you show requires threaded "mid-blade" mounts on the fork legs to fit properly. I would not use U-bolts or P-clamps on an aluminum fork either. Aluminum is more notch-sensitive than steel and any scratches produced by the clamps are potential failure points. There is a good reason nearly all touring bikes come with steel forks and it isn't just tradition.

I have no problems with carbon forks and have them on three of my bikes and rode a bike with an aluminum fork for almost 30,000 miles but I would stick with steel if I was going to mount a front rack by any method.
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Old 02-07-13, 10:16 AM
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I have an older Redline R540 hybrid bike that I replaced the front fork with a Diamondback aluminum fork that had factory mid length mounting bosses on it. I would not hesitate to put a front rack on that fork however I would not overload it like I would consider doing to a front rack mounted on a steel fork with mid length mounting bosses.
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Old 02-07-13, 10:41 AM
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I am sure it depends on the design and construction of the fork as much as the material, but I would bet 95% of carbon forks are lightweight racing types that are not intended to be used with a rack. Aluminum forks are kind of a rare bird and I don't know that you can make generalizations one way or the other... and VO is just making a CYA statement so no-one clamps the rack over their 300 gram racing fork falls under a dump truck and sues.

Anyhoo, it depends on the fork. If the manufacturer of your fork included low-rider rack bosses mid way down the legs, then it was likely intended for use with a rack. However, you need to use your best judgement. I have an aluminum fork on a touring bike that has the bosses but is too light for me to be confident in loading it up... I have ridden the bike hard and there is no reason for me to be nervous except for the noticable flex under braking and over rough terrain.
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Old 02-07-13, 04:43 PM
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Catte, My own unscientific possible reason is the possible squeezing/crushing of a CF or an aluminum fork leg when installing a mid mount rack. If the mid mount is sleeved inside there maybe no issue at all. Cannondale built one of the nicest tourers around for years, but used a cro mo fork.

Brad
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