Originally Posted by rpenmanparker

Uh oh, every now and then I get in a mental quagmire where nothing seems to be as it should. I was trying to figure out why crossed spokes give higher stiffness as Rob says when EVERYONE KNOWS higher bracing angle (θ) means more stiffness. So I did the trig. First, as I understand it bracing angle is the angle of the spoke from the vertical at the flange to the rim. Lets say the length of the spoke is h (for hypotenuse). Suppose you want to shift the rim x mm to the right. Then x = Δh(sin θ). Or rearranging, Δh = x/sin θ. Assuming the only way for the rim to move is for the spoke to get longer, then all the force required must stretch the spoke, and the force F will be the change in length multiplied times the tensile modulus m. So F = mx/sin θ. The sine of the angle increases as the angle increases, so as the bracing angle increases, the force needed to stretch the spoke the required length to realize an x mm lateral shift DECREASES. Whoops. How can that be? First it explains why crossing could stiffen the wheel, but it is contrary to what EVERYONE KNOWS. All I can say is that other things are going on. At very low bracing angle there is probably more spoke bending and rotating in the spoke hole than stretching to accommodate a lateral force. Higher bracing angles may produce a more STABLE wheel but not a stiffer one. Think a 90 deg. angle; the only way lateral movement could occur is by spoke stretching. Now think a 0 deg. angle. There would be many more modes of movement besides spoke stretching. The wheel would be infinitely delicate even though in theory there would be no force large enough in the lateral direction to stretch the spoke along its length. Interesting, huh?

Originally Posted by lazerzxr

I build my own wheels as I have a couple of powertaps. at #165 I find the 24/28 spoke combo works a charm and wish more rims were available with these counts. Having said that, you can build a 28 hole deep carbon rim (enve and others) or Hed Jet4 come in 28 along with FF, its sometime more difficult to get a 24 hole alloy front (mavic dont make one for example). In my opinion 90% of normal size blokes could ride a 24/28 and be happy whether they go deep carbon or shallow alloy. I have also found if you break one it is still rideable.

the only time I ever got brake rub was using HOPE steel rod skewers - junk skewers!

Originally Posted by caloso

I mounted up the wheels in question this morning (I have a race tomorrow and I sometimes use the Friday commute as a shakedown) and instead of using the open cam skewers that came with the wheels, I used an ugly, old pair of Shimano Tiagra/RSX/? closed cam skewers. Guess what? No rub.

I am still intrigued by the idea of rebuilding them as 2x. Making a slight trade of radial stiffness for lateral stiffness makes a lot of sense for race wheels, particularly for crits.

Originally Posted by Clipped_in

Interesting. What kind of hubs & axles are on those wheels?

BTW, I'm a bigger guy that I rides 2X laced front wheels and likes them.

Thanks to those contributing to make this such a good thread!

Originally Posted by caloso

I used an ugly, old pair of Shimano Tiagra/RSX/? closed cam skewers. Guess what? No rub.

Originally Posted by caloso

I mounted up the wheels in question this morning (I have a race tomorrow and I sometimes use the Friday commute as a shakedown) and instead of using the open cam skewers that came with the wheels, I used an ugly, old pair of Shimano Tiagra/RSX/? closed cam skewers. Guess what? No rub.

I am still intrigued by the idea of rebuilding them as 2x. Making a slight trade of radial stiffness for lateral stiffness makes a lot of sense for race wheels, particularly for crits.

Originally Posted by rpenmanparker

Could you explain what you mean by open and closed cam skewers? Thanks.

Originally Posted by caloso

Not as well as Sheldon can:

https://sheldonbrown.com/skewers.html


[on edit: I should have read this article a long time ago!]

Originally Posted by rpenmanparker

First, as I understand it bracing angle is the angle of the spoke from the vertical at the flange to the rim. The sine of the angle increases as the angle increases, so as the bracing angle increases, the force needed to stretch the spoke the required length to realize an x mm lateral shift DECREASES.

Originally Posted by caloso

I mounted up the wheels in question this morning (I have a race tomorrow and I sometimes use the Friday commute as a shakedown) and instead of using the open cam skewers that came with the wheels, I used an ugly, old pair of Shimano Tiagra/RSX/? closed cam skewers. Guess what? No rub.

I am still intrigued by the idea of rebuilding them as 2x. Making a slight trade of radial stiffness for lateral stiffness makes a lot of sense for race wheels, particularly for crits.

Originally Posted by lazerzxr

Read that over a few times and you will see where you have gone wrong. Think in terms of the spoke, when a lateral load is applied it is the spokes job to provide the equal and opposite lateral force to prevent the rim moving. What is the most appropriate orientation for the spoke to do this? Remember that as the spoke stretches more, the force it provides increases. Think of a spoke pulling down almost vertical trying to resist a 100kg lateral load, The lateral deflection will need to be huge before the spoke force builds sufficiently to resist the load

Originally Posted by rpenmanparker

Terribly sorry. You are absolutely right. I didn't rearrange the vector component directions to make the line of the spoke a component of the lateral deflection. I had it the other way around as you would do when figuring lateral tension during spoke tightening. In a way I am relieved. I knew something was wrong. Thanks for a very good catch. But I wonder about the other things I said regarding lacing stiffening the wheel. Despite my other error, can any of that be correct?

Originally Posted by lazerzxr

As I understand soldering spokes was done to keep a broken spoke from flying all over the place and causing trouble, it keeps it in place. It certainly doesn't add any additional load path, the force in a spoke is there because equal reactions exist at the hub and rim, soldering the spokes afterwards has no effect on that. As the spoke load varies in use, load will always be attracted to the stiffest load path, which will always be axially along the spoke, nothing will get transferred across the solder because the spoke that gets crossed is in the wrong orientation. To demonstrate, think of holding a pencil and a rubber band together and pulling them at the same time - all of the load is resisted by the stiff pencil and the rubber band does nothing. When thinking about spoke bending, remember that all spokes are connected to the rim, so when the rim deflects they all move with it, therefore they cant support each other. There is no moment connection at the end of a spoke, rotation is allowed, since load can only be applied at the ends, it is not possible for a spoke to work in bending in a built up wheel.

Originally Posted by rpenmanparker

That is not what I had heard. HOWEVER, please see the text of an article by Jobst Brandt pasted in below. I appears that you are absolutely correct. That is two strikes for me. I think I will bow out now in favor of those who really know what they are talking about. Thanks for straightening out my mess.

Robert

Originally Posted by Psimet2001

Crappy skewers are the bane of my existence.

"Hey, I have this creaking sound coming from the rear wheel..."
"Change your skewer."
"That makes no sense."
"Do it anyway."

...."hey that sound went away."

Originally Posted by Ricanfred

Any skewers in particular that you recommend? IME Bontrager ones are junk! They rattle...