Drawbacks to 2X Lacing?

[oliver1850]

I guess I should buy a book...

Is there a serious shortcoming with 2x lacing on 32 or 36 spoke wheels? I'm wanting to use up some spokes that are on the short side. I'm pretty easy on wheels, last broken spoke was around 1995. thanks.

[Peter P.]

I build all my 32H front wheels 2x. No problems.

I don't do that with rear wheels because they aren't tangental enough. I fear they'll fatigue early from rear wheel torque loads. I don't care to experiment to find out, either.

[christian]

Peter P covered the big one - for driving torque, you ideally want the spokes to have as much bracing as possible from the hub, which means that they should leave the hub tangent to it, which in turn means 3x for 32h/36h wheels. How important this is in practice, I don't know - because I've always done it by the book.

For front wheels, no issue there.

The only other thing to consider is - once you've laced the hubs this way, you can't go back and lace them 3x - the hub flange takes a set. So, for me, it's a little bit about the hubs. Would I lace a set of 105SC hubs 2x 32h? Yes. A pair of silver NOS Record hubs? No.

[oldpotatoe]

I guess I should buy a book...

Is there a serious shortcoming with 2x lacing on 32 or 36 spoke wheels? I'm wanting to use up some spokes that are on the short side. I'm pretty easy on wheels, last broken spoke was around 1995. thanks.

3 cross on a 32 or 36 hole wheel, all else being equal, is a stronger wheel.

Evaluate you, your riding style, weight and the rim being used. 'Probably' ok on the front, wouldn't do it on a rear.

Bottom line to me is 2 cross does nothing to make the wheel better, when compared to 3 cross, in 32h.

Just trying to use spokes doesnotapply to me, IMHO.

[wallymann]

i'm 6'1" and weigh ~175# and my standard build is 28H radial front and 32H 2-cross in the back. for my "special duty" wheels, i'll even go with radial lacing on the non-drive side in back.

roads up here in MI are pretty freaking rough from frost heaves and heavy traffic and vanishing municipal budgets and 2X lacing works wonderfully. i even dabble in racing when i can, and i have yet develop sufficent "driving force" to stress the modest tangential geometry of the 2x lacing in back enough to cause any durability problems.

unless your name is cavendish or greipel or kittel and pro-tour teams are clamoring for your services, i'd say you're fine with 2X lacing.

[Mark McM]

I guess I should buy a book...

Is there a serious shortcoming with 2x lacing on 32 or 36 spoke wheels? I'm wanting to use up some spokes that are on the short side. I'm pretty easy on wheels, last broken spoke was around 1995. thanks.

How about a research paper instead of a book?

Spoke lacing pattern (number of crossings) on a rear wheel have little affect on the fatigue life of the spokes, according to Professor Henri Gavin of Duke University, who wrote this study on the subject:

http://people.duke.edu/~hpgavin/papers/HPGavin-Wheel-Paper.pdf

In this study, in addition to performing finite element analysis of 36 spoke wheels with 2, 3 and 4 crossings, he also performed both static and dynamic testing of actual wheels. He instrumented the spokes of the wheels with strain gauges and measure the actual spoke strains while the wheels were ridden. From the conclusions:

"The spoke pattern affects the over-all radial stiffness of the wheel more than it affects the spoke strains. From a theoretical analysis, a numerical analysis, static experimental analysis, and in-service measurements, the spoke strains appear to be insensitive to the pattern of the spoke lacing."

[FlashUNC]

Nearly all of my wheels are 2x. No issues.

And I'm a pretty hefty guy these days.

[oliver1850]

Thanks for all the comments. The range of opinions is about what I expected, but I wasn't expecting to find scientific test results. I'd never have found that on my own, so special thanks for posting the link.

The most surprising thing I've read in the study so far is that spoke guage affects lateral and radial stiffness to a much higher degree than lacing pattern. It would have been interesting to see durability results relative to spoke guage too. Also interesting is that the strain guage data shows 2x and 3x relatively close together compared to 4x, which would appear to give significantly less strain. The finding that lacing pattern has more affect on strain during lateral as opposed to radial loading is something I wouldn't have guessed. That's good news for me as most of my cornering is done at intersections where I'm typically going slow anyway.

[ergott]

If you think about it, it makes perfect sense. The spokes are almost perpendicular to the vertical loads so they support them for better than lateral loads. Imagine trying to hold up a tilted tree with a rope. You have much better leverage the further you stand away from the tree. This is why I always say flange geometry matters a lot.

As to the OP, I have built my share of 2X front wheels and 2X on the non drive side of the rear wheel with no problems. I would prefer 3X at least for the drive side as that's were most of the torque loads are concentrated when stomping on the cranks. Still nothing wrong with 3X all around either.

[Mark McM]

The most surprising thing I've read in the study so far is that spoke guage affects lateral and radial stiffness to a much higher degree than lacing pattern.

This should be surprising at all. The spokes are what connect the rim to the hub, so the stiffnesses of the spokes will obviously be a major factor in the stiffness of the complete wheel. Changing the lacing pattern really just changes the lengths, angles, and lateral offsets of the spokes. Going from radial to tangential, the length and lateral offset of the spokes only changes a few percent. The angle of the spoke at the rim only changes a few degrees. These changes will likewise affect the relative stiffnesses and stresses/strains of the spokes by only a few percent.

Compare that to changes in spoke gauge. The stiffness of a spoke will be proportional to its cross-sectional area. Commonly available spokes have diameters of between 1.5 mm and 2.0 mm, or cross-sectional areas between 1.77 mm^2 and 3.14 mm^2. The thinnest spokes will therefore have only about half the stiffness of the thickest spokes. The relative difference in stiffness due to spoke gauge will be much larger than due to lacing pattern.

[oliver1850]

If you think about it, it makes perfect sense. The spokes are almost perpendicular to the vertical loads so they support them for better than lateral loads. Imagine trying to hold up a tilted tree with a rope. You have much better leverage the further you stand away from the tree. This is why I always say flange geometry matters a lot.

As to the OP, I have built my share of 2X front wheels and 2X on the non drive side of the rear wheel with no problems. I would prefer 3X at least for the drive side as that's were most of the torque loads are concentrated when stomping on the cranks. Still nothing wrong with 3X all around either.

What I meant was, I had no idea that the lateral loads were high enough to seriously impact strain or fatigue life, not that wheels could absorb lateral loads as easily. I think of wheels as taking a beating mainly due to surface roughness. That's still probably accurate for the way I ride. Perhaps that has more to due with why I don't have spoke breakage as any other factor.

[Mark McM]

What I meant was, I had no idea that the lateral loads were high enough to seriously impact strain or fatigue life, not that wheels could absorb lateral loads as easily. I think of wheels as taking a beating mainly due to surface roughness. That's still probably accurate for the way I ride. Perhaps that has more to due with why I don't have spoke breakage as any other factor.

The research paper didn't say that wheels experienced high strains due to lateral loads, it said that wheels had higher strain sensitivity to lateral loads than radial loads. In other words, one Newton of lateral load produces more strain than one Newton of radial load. Which means it is a good thing that lateral loads on wheels are much smaller than radial loads in normal usage.