Another fastener question: why thru axles are used without nuts and washers?

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musiclover
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by musiclover

I wonder why thru axles are used without nut on the other end to help to secure it further? There are also no washers most of the times at the "bolt head".

Will any of this improve the reliability of the joint?.. (Provided, of course, one has enough thread and fastener length for it).

GregR
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by GregR

A nut is unnecessary, as a threaded insert is moulded into the fork. As for the washer, in my opinion one is not required as the two relevant surfaces are formed to match. Adding a washer would not improve the joint.

by Weenie


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musiclover
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by musiclover

GregR wrote:
Sun Oct 24, 2021 3:46 am
A nut is unnecessary, as a threaded insert is moulded into the fork. As for the washer, in my opinion one is not required as the two relevant surfaces are formed to match. Adding a washer would not improve the joint.
I understand that the drop out acts as a nut. The question is: will an additional nut on the outside of that construction improve the joint? Also, this will allow to use a spring washer on that side which will protect the joint from loosening from vibration on that side.

As for the flat washer on the head side... Will it spread the load better if it is bigger than the thru axle head? Will it ease the torquing / fastening of the joint?..

GregR
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by GregR

No

TobinHatesYou
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by TobinHatesYou

You're more likely to damage the threads on your thru-axle by having a nut in addition to the one built into the fork. You're effectively creating a flexible, variable thread pitch interface after all.

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musiclover
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by musiclover

GregR wrote:
Sun Oct 24, 2021 4:18 am
No
Yes. (We are referring to a 3 year old level of argumentation, are we?)
TobinHatesYou wrote:
Sun Oct 24, 2021 4:31 am
You're more likely to damage the threads on your thru-axle by having a nut in addition to the one built into the fork. You're effectively creating a flexible, variable thread pitch interface after all.
What is the difference of a normal bolt with two nuts and a thru axle with a spring washer and a nut?.. How do two nuts of the same thread pitch create a variable thread pitch?

GregR
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by GregR

I did not realize that you were arguing. I apologize for missing that. You asked three questions. The answers are all "no". So, no, no, no would have been more accurate.

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musiclover
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by musiclover

GregR wrote:
Sun Oct 24, 2021 5:00 am
I did not realize that you were arguing. I apologize for missing that. You asked three questions. The answers are all "no". So, no, no, no would have been more accurate.
No, I was not arguing, I recommend educating yourself on the term "argumentation" :wink:
Also, my initial questions were not closed, I am trying to understand this joint from mechanical perspective.

TobinHatesYou
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by TobinHatesYou

musiclover wrote:
Sun Oct 24, 2021 4:54 am

What is the difference of a normal bolt with two nuts and a thru axle with a spring washer and a nut?.. How do two nuts of the same thread pitch create a variable thread pitch?

When you tighten the top nut on a double-nut, it's not pulling the whole bolt through. It is putting excessive loads on the bolt threads. This is undesirable, especially in a system that sees lots of shock/impact/vibration.

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musiclover
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by musiclover

TobinHatesYou wrote:
Sun Oct 24, 2021 5:27 am
When you tighten the top nut on a double-nut, it's not pulling the whole bolt through. It is putting excessive loads on the bolt threads. This is undesirable, especially in a system that sees lots of shock/impact/vibration.
It only puts excessive load on the threads if you are using excessive force when tightening it. If you are using a nyloc bolt which is only done with a minimal tension it could only improve the safety of a joint?.. Or am I wrong?

TwiggyForest
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by TwiggyForest

Are you having issues with thru-axles coming loose?Anyway, a second nut is usually used as a lock nut to prevent accidental loosening of the nut/bolt, or will not 'improve' the joint. The best thing you can do to improve clamping force and retention is torque the thru-axle sufficiently.

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musiclover
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by musiclover

TwiggyForest wrote:
Sun Oct 24, 2021 5:55 am
Are you having issues with thru-axles coming loose?Anyway, a second nut is usually used as a lock nut to prevent accidental loosening of the nut/bolt, or will not 'improve' the joint. The best thing you can do to improve clamping force and retention is torque the thru-axle sufficiently.
No, I am not having an issue of a thru axle coming lose. I had an issue with a poorly designed derailleur hanger being held on two M4 bolts coming loose and destroying the thread of a hanger. But it's design is similar to a thru axle so a bit easier to explain.

Maddie
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by Maddie

In that case just get a new derailleur hanger and add some middle strength loctite to the m4 bolts.

Karvalo
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by Karvalo

musiclover wrote:
Sun Oct 24, 2021 4:00 am
I understand that the drop out acts as a nut. The question is: will an additional nut on the outside of that construction improve the joint?
Will the nut on a standard QR be improved by the addition of a second nut?

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musiclover
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by musiclover

Maddie wrote:
Sun Oct 24, 2021 6:25 am
In that case just get a new derailleur hanger and add some middle strength loctite to the m4 bolts.
The stock nuts had a thread locker from the factory, unfortunately, it did not work.
Karvalo wrote:
Sun Oct 24, 2021 7:57 am
Will the nut on a standard QR be improved by the addition of a second nut?
Isn't QR equipped with a preload lever? I thought it's design is different to a standard thru axle without the preload handle.

by Weenie


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