Stainless vs chromoly skewers - least flex

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432r
Posts: 52
Joined: Mon Apr 25, 2011 2:09 pm

by 432r

I am having some trouble with tyre rub (due to tight tolerances) in the seat stay on my bike. I am eliminating each form of flex bit by bit.

My question is - which would deliver less flex under climbing/sprinting load:
-say a zipp stainless steel skewer
Vs
- a chromoly based skewer eg a ffwd or similar. I think they are hollow chromoly axle.

I am 'guessing' you could get 1-2mm of flex under stress for a skewer rod potentially.
Thanks


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mike
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by mike

i would go with a titanium skewer, slightly thinner tires first. if that doesn't work, it may be that you have a flexy wheel. i would stay away from the 34 gram skewers or lighter because they don't hold rear wheels as well.

mimason
Posts: 654
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Location: Florida

by mimason

If you are dabbling with flex via skewers then go all out with Shimano skewers and work backwards. If the Shimano's are not fixing your issue then its likely no skewer will.

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bikerjulio
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Joined: Fri Dec 11, 2009 10:38 pm
Location: Welland, Ontario

by bikerjulio

The skewer is either going to hold the wheel in place, or it is going to allow it to move within the dropout. They don't "flex". If the wheel moves, it will stay moved IME.

OP should be looking at wheel flex as the culprit.
There's sometimes a buggy.
How many drivers does a buggy have?

One.

So let's just say I'm drivin' this buggy...
and if you fix your attitude you can ride along with me.

http://www.youtube.com/watch?v=GekiIMh4ZkM

432r
Posts: 52
Joined: Mon Apr 25, 2011 2:09 pm

by 432r

Alright, I just find it hard to believe that a new 24 spoked 404 is flexing more than 3mm with a 74kg rider underneath it.


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F45
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by F45

Steel is the stiffest of the materials used in skewers. Get Dura Ace skewers. If that doesn't fix your problem, it ain't the skewers.

Qman
Posts: 118
Joined: Wed Oct 23, 2013 9:55 pm

by Qman

Two parts to my answer:
1. If you have a Chromoly Steel, a Stainless Steel, and a titanium skewer, and if all have the same diameter shaft, then the stiffest is the Chromoly, follow closely by the Stainless Steel. The titanium is considerably more flexible.

2. Number 1 doesn't matter because of what bikerjulio said. Any skewer should be stiff enough to keep the dropouts pressed firmly against the axle. The skewer will have no influence on your tire rub. The cause of tire rub can be quite complicated. Sometimes it is because the rim is very stiff and the spokes relatively flexible (or not tensioned enough). The rim stays flat, the spokes flex, and the rim touches the frame. If the rim is more flexible then it will bend locally at the ground and not flex higher up.

Has the bike always been like this, or did you recently change wheels or tires? If the problem started when you made some changes, then let us know what changes and we may be able to help out.

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fa63
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by fa63

If you think skewers might be the culprit, then you might also want to look at DT Swiss RWS skewers. Those suckers hold the wheel in tight.

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Rick
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by Rick

I believe that skewers do flex. I have an old horizontal dropout frame bike that I can twist the wheel out of alignment in a hard sprint when I tried to use Ti skewers; and I am not very powerful. I don't think I have ever hit 1000 Watts.
When I go back to my prior generation steel skwerers (Campy, Dura Ace, Suntour, Ultegra) the problem never happens.

I know this is slightly different than allowing wheel flex; but I just think it indicates that Ti skewers are flexing.

mike
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by mike

I have had 404 and 1080. Both flexed. I could see it when riding. It was the spokes flexing

tranzformer
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by tranzformer

^ Were you looking at your rear wheel while sprinting?

Qman
Posts: 118
Joined: Wed Oct 23, 2013 9:55 pm

by Qman

I believe that skewers do flex. I have an old horizontal dropout frame bike that I can twist the wheel out of alignment in a hard sprint when I tried to use Ti skewers; and I am not very powerful. I don't think I have ever hit 1000 Watts.
When I go back to my prior generation steel skwerers (Campy, Dura Ace, Suntour, Ultegra) the problem never happens.

I know this is slightly different than allowing wheel flex; but I just think it indicates that Ti skewers are flexing.


Yes, I agree that this is different than allowing wheel flex. If the axle has slipped in the dropout then the skewer didn't generate enough clamping force, and therefore enough friction, to stop the axle slip. Skewers work in tension. When you clamp the lever the skewer goes into tension. The Ti skewers are more flexible in tension than steel ones. That means that you need a larger cam to stretch the Ti more so that you can generate the same amount of clamping force as the steel skewers. However, the OP didn't say anything about the axle slipping in the dropouts, so that means the skewers are doing their job. The axle isn't slipping in the dropouts so getting a stiffer skewer won't help with the wheel rub.

Note that the Zipp 404 an 1080 are very stiff rims. They don't bend sideways very much. The spokes allow the rims to shift sideways and can result in wheel rub.

Marin
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by Marin

If your axle stubs are moving inside the dropout, put thin tape on them.

wingguy
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by wingguy

Rick wrote:I believe that skewers do flex. I have an old horizontal dropout frame bike that I can twist the wheel out of alignment in a hard sprint when I tried to use Ti skewers; and I am not very powerful. I don't think I have ever hit 1000 Watts.
When I go back to my prior generation steel skwerers (Campy, Dura Ace, Suntour, Ultegra) the problem never happens. .


That's not flex, that's insufficient clamping. Light ti skewers are external cam which don't have as much leverage as internals like campagnolo/DA

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432r
Posts: 52
Joined: Mon Apr 25, 2011 2:09 pm

by 432r

You guys have been helpful.
It's a 24 spoke 2014 404 FC. With zipp stainless steel skewers. I only have 3.5mm clearance (tyre to frame at seat stay) and I had rubbing with 23mm gp4000s. So I moved to 22mm attacks.
I Think it will still rub (just) and so I wanted to look to other causes too (such as skewers) to see what else it could be.


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