Spoke stiffness
 

Hey guys, I found a few topics on this, but couldn't find quite what I was looking for. My friends and I were debating about spoke strength and stiffness and we're wondering what the stiffest, not strongest spoke would be on a track wheelset, 32h 3x. Obviously bladed has that strength, but are they the stiffest?

The thickest round spoke you can get through the holes in the hub. 14g non-butted is the stiffest commonly used but there are 13g and even 12g spokes out there and appropriate nipples for special applications.

A radial front wheel will also be stiffer.

Butted spokes have better fatigue strength due to their elasticity and will last longer before breaking.

rustymongrel got it. Also, if you are going metal, don't even think about a non-steel spoke. (A titanium spoke, while quite strong, is twice as stretchy for the same diameter. Aluminum is worse.)

Ben

Stiffness is purely a function of the cross section of the spoke. For round spokes it easy, fatter is stiffer. However comparing the cross section of bladed and oval spokes is a bit more difficult.

There is an easy way. Weigh them. For the same length, more weight means thicker cross section, and more stiffness.

It's harder to do this for different materials, but not impossible. Find the Young's moudlus and apply it when comparing sections.

There's couple of additional things to consider with respect to wheel stiffness:

1) Hub flange size - the higher the flange the stiffer the wheel

2) Rim stiffness - a stiff high profile rim can produce a very stiff wheel with fewer spokes at a higher tension.

Beyond the wheel, the tire width should be about the same as the rim width if stiffness is desired. An oversized tire on a narrow rim will make the stiffest wheel feel like a soft wheel.

A radial laced wheel will have more lateral stiffness because of the shorter spokes but a 3-cross wheel will have a better torsional stiffness. This article of slowtwitch can be useful.

In the end, what creates a stiff wheelset is high spoke tension, short spoke length (with high flange hubs and deep rims)and high spoke bracing angle.

The effects of flange size depend on the spoke pattern.

Non-torsional differences are greatest with radial spokes where bigger flanges mean shorter spokes. However Flange size has zero effect on non-torsional stiffness with full tangent (ie. 4x36h, 3x28h) patterns, since the spoke length is unchanged.

Torsional stiffness is the opposite, with zero difference with radial patterns, and maximum effect with tangent. Note, that for torsional effects, the key element isn't spoke length, but the lever arm (right angle distance from spoke to center).

I went to Pro Wheelbuilder.com's spoke length calculator and from 0X to 4X(where permitted) the high flange hub used shorter spokes for the 28, 32, & 36 spoke combos. That said, the differences in lengths decreased as I went from 0X to 4X. Also, given similar patterns(angles), shorter spokes will have less ability to deflect under torsional loads. This would hold true for radial patterns up through 4X.

Technically the heaviest gauge spokes your hubs/rims can take will be the stiffest but often times there is a point where you just don't need stiffer. I built a set of 3x 32h wheels with 14/15/14 spokes for Danny Robertson and he claimed they were as stiff as his discs and he was at one point one of the strongest US sprinters out there. Those were on pretty standard Dura Ace hubs and an Origin 8 rim with a similar profile to Deep V's. So yes, technically you can chase the theoretical stiffest spoke out there but there is a point where you are just adding weight and not any noticeable improvement in stiffness.

Spoke stiffness is totally unimportant. If it was we'd used fat tubular spokes.

This feels like a thread from 1996.