Using two different gauge spokes on asymmetrical wheels

[OneTrackMind]

I just came across this page about wheel building where it is suggested that thicker spokes be used on the right side of a bicycle rear wheel. Presumably the same idea could be applied to asymmetrical unicycle wheels with inboard disks.

An elegant trick to build a stronger rear wheel is to use thicker spokes on the right side than on the left side. Spokes with a 2mm shaft on the right and with a 1.6 mm shaft on the left balance nicely; with this combination, spokes on both sides ring at approximately the same pitch, indicating that they are both carrying optimum tension.

You may ask why this approach makes a better wheel than using thicker spokes on both sides. After all, thick left-side spokes would be stronger. They would also be at the same tension as the lighter spokes would, though at a lower musical pitch. But because they elongate less, thick spokes on the left actually go slack and give up control of the rim under a lighter weight load; and even when the load is not so great that they go slack, the rim warps to one side at the bottom of the wheel where it bears weight, due to the unequal lateral component of stiffness of the right-side and left-side spokes. The reason that thinner spokes on the left work better and last longer is that they are stretched by the same amount and have the same stiffness against lateral (side-to-side) motion of the rim as the thicker spokes on the right.

I’ve never noticed wheels using two different gauge spokes but then I have never looked for it. I will be looking now.

Anybody had experience with this concept?

[bouin-bouin]

AZll rear bikes wheels are assimetrical and none of them use different spokes gauge according to my knowledge

[finnspin]

I find it very weird that I constantly see people worrying about asymmetrical wheels and looking for fixes to their apparent instability, but I am yet to see anyone actually having any issues at all.

[MrImpossible]

I used to do that with my mountain bike rear wheels, mostly to avoid spoke breakage. In theory the spokes would go slack less often, and not suffer so much metal fatigue. It worked fine, but I don’t put nearly as many miles on my unicycle wheels, so fatigue failure hasn’t really been a problem*.

But changing spoke thickness doesn’t make a symmetrical wheel; I would rather get an off-center rim and have everything be the same on both sides as far as the spokes are concerned. I have one of those on my road bike rear wheel, and I like it.

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• I did have a bunch of spokes fail on my Torker DX, which was a poorly made unicycle in many ways. All the breaks were in the bottom quadrant of the wheel in my normal hopping position, so it probably was from spokes going slack. I rebuilt the wheel with new spokes and never had another problem.

[kunstrasen]

1.) this is done on Mtb handbuild wheels since years. I have been riding such a rear wheel on a Mtb for many years

2.) Stock M/unis all use the worst possible spokes: just straight spokes. And all is machine build.

3.) Stock M/unis still work fine for years as mentioned. Reason: The rims a just completly overkill such as 900 gr for a 27,5 rim

4.) there is definatly potential for improvement…

[saskatchewanian]

I’ve mixed regular and double butted spokes on a dished wheel before. Not because I figured it was a particularly good idea (though I figured it would not hurt for the reasons stated above) but because that is what I had in the right size.

Generally the rim is what limits the amount of tension you can put in the wheel, not the spokes, so I think its really more about going thinner on the slack side than thicker on the tight side.

[UniMyra]

From Sheldon Brown’s wheel building page: (http://www.sheldonbrown.com/wheelbuild.html)

[Following comment is by John Allen]
I recommend thicker spokes for the right side of a dished rear wheel (a wheel used with a multi-sprocket cluster) than the left side, because the left-side spokes are under lower tension. The thinner spokes on the left side will be working more nearly at the tension for which they are designed, and so they will be stretched more and less likely to go slack. For more details, see my article on spoke tension.

[elpuebloUNIdo]

@finnspin

I find it very weird that I constantly see people worrying about asymmetrical wheels and looking for fixes to their apparent instability, but I am yet to see anyone actually having any issues at all.

I had a big problem on my 26" Oracle. Unfortunately, I didn’t know enough, technically, when the problem happened to correctly identify the cause of the problem.

What happened is that the wheel started riding closer and closer to one side of the frame. This could have been in part caused by the asymmetrical wheel build. If I recall, I was spending a lot of time UPDing on hills and remounting at a 90 degree angle to the hill. I was stronger mounting with the left side of the wheel facing downhill. Many of the mounts were very rough, and I’m pretty sure this put a lot of tension on the spokes. However, I don’t know how that situation is related to the spoke-strength of the asymmetrical wheel. The same issue could have happened on a normal wheel.

[saskatchewanian]

@elpuebloUNIdo

I had a big problem on my 26" Oracle. Unfortunately, I didn’t know enough, technically, when the problem happened to correctly identify the cause of the problem.

What happened is that the wheel started riding closer and closer to one side of the frame. This could have been in part caused by the asymmetrical wheel build. If I recall, I was spending a lot of time UPDing on hills and remounting at a 90 degree angle to the hill. I was stronger mounting with the left side of the wheel facing downhill. Many of the mounts were very rough, and I’m pretty sure this put a lot of tension on the spokes. However, I don’t know how that situation is related to the spoke-strength of the asymmetrical wheel. The same issue could have happened on a normal wheel.

That sounds more like a bearing slipping than an issue with a wheel to me. Are you using spacers between the cranks and the bearing?

[aracer]

I’ve built a rear wheel for my mountain bike with thinner spokes on the left side - the theory is it helps prevent the spokes that side going slack as they stretch more (so they . Don’t think I’d spoke a unicycle wheel like that - partly because the dish on an assymetric uni wheel isn’t as much as on a rear bike wheel, but mainly because doing so makes the wheel less stiff laterally and hence not as strong. That’s not a big issue on a rear bike wheel where the lateral loads are low, it’s more of an issue on uni wheels used for hopping, or anything other than just straight line riding. In fact there’s a good argument for building uni wheels with straight gauge spokes for improved stiffness.