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Wheels generally used to have more spokes.

old timey 36-spoke wheel

As technology improved and markets changed, manufacturers have taken to making wheels with fewer (and often heavier spokes). I've been told this comes at the expense of having a slightly heavier rim to maintain strength and stiffness.

a newer aksium wheel, 20 spokes

I realize that aerodynamics generally has more impact on performance than shaving a few grams, but I was wondering if any manufacturer ever tried making wheels with more, but finer spokes, perhaps to save on rim weight rather than spoke weight. Was this ever done?

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    Sheldon brown talks about this as the great spoke scam of the 80's. I always assumed since he does not reference a manufacturer that bucked the trend no manufacturer was in fact heading the other direction. – Glenn Dec 20 '11 at 5:52
  • @Glenn That could make an answer. – jv42 Dec 20 '11 at 10:11
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    With more spokes (beyond 32 or so) you have to make the hub slightly heavier, though that's probably negligible. As to the supposed aerodynamic advantage, I'm skeptical -- the rim profile breaks up airflow enough that the increased spoke count probably has only marginal aerodynamic effect. In any event, like many parts of a bike it's more about "sex" than practicalities. (Ever heard a spoke break on one of those low-count wheels? It sounds like a gunshot, and you can hear it a block away.) – Daniel R Hicks Dec 20 '11 at 12:29
  • @Glenn -- Of course, you can still build your own wheels (though likely it's getting harder and harder to find the right components.) – Daniel R Hicks Dec 20 '11 at 12:31
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To the best of my knowledge, and my ability to find reference in any old catalog or tech manual, no, that concept has not been tried on a commercial scale at least. It may have been tried on a local scale.

I don't have the math to prove it, but I suspect the balance point between how thin the spokes would need to be to reduce the weight enough to offset the additional weight of more spokes, and the tensile strength those spokes would require to maintain the strength of the wheel without breaking would prevent any weight benefit from being gained, and I know that spokes thinner than 1.8mm have a far greater likelihood of breakage. The butted 2.0/1.5mm spokes which were popular in the late 90's for XC racing wheels proved that to me.

Perhaps we could get the Math or engineering SE guys to comment here?

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  • Don't forget about the nipples (that's what she said?)! The more spokes you add, the more nipples you will need to have which will increase overall weight. One wheel company to look at for light and strong spokes is Topolino. Their top end wheels have spokes created from carbon fiber. – Vincent Agnello Dec 21 '11 at 5:06
  • The potential weight advantage comes from less rim. A rim with less spokes needs to be stronger. A rim with more spokes can be thinner and lighter. ... maybe. – Glenn Dec 21 '11 at 7:52
  • @Glenn: I see what you're saying now, but only a very small amount of the strength of a wheel comes from the rim's structural properties. It is almost entirely a function of balance between the spokes on opposite sides and opposite circumference points, for lack of a better descriptor. The "strength" of the rim without spokes is essentially non existent. Which is why wheels can hold a large (100-120 kilo) weight from a top load, but less than 10 kilos usually from a side load. The rim is as light as it can likely be made safely already. Any weight differential would come from a spoke mass. – zenbike Dec 21 '11 at 8:01
  • @user973810 You need two holes in the rim for each spoke (through the cross section of rim). Surely that will offset the weight of the spoke and nipple a bit (not sure how much). – Jason S Dec 26 '11 at 22:09
  • @JasonS: Not enough. As I said, it's the balance of the weight of the spokes versus the strength of the spokes required which is the issue. – zenbike Dec 27 '11 at 9:54
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Another thing to consider in the question of weight of a bicycle wheel is the distribution of the weight and the effect it has on its rotational inertia. A wheel with fewer spokes and deeper rim profile (typically necessary to handle having fewer spokes) will be more efficient in terms of aerodynamics, but will be more difficult for the rider to accelerate. Losing a few grams at the outside of a wheel can make a huge difference in how a bicycle feels even to a non-professional.

Finer spokes have been done to varying degrees over the years, but are limited by material and the need for adjusting tension during the building process and ongoing maintenance. Spokes need strength most at the mounting points (traditionally a threaded nipple and J-bend). Also depending on the adjustment method (threaded nipple, etc...) a spoke must resist that twisting motion or have provisions to allow it to be held stationary while the nipple is adjusted. Double or even triple butted spokes are an attempt to concentrate material where it is needed the most, but at a higher cost of manufacture and less durability due to susceptibility to material flaws and excess work hardening in some cases.

Also, I am kind of fuzzy on this, but I seem to recall either Shimano or Zipp stating that the tipping point for number of round spokes to have an aerodynamics effect was 16 or 12. Any number above that did not have any significant difference in changing aero effects. Regardless it was a pretty low number.

Long story short, wheel/rim/spoke combinations can make a huge difference in the feel, durability and price of your bicycling experience and due to the huge variability in riding style and preference, no one combination is the perfect answer for all riders in all situations.

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    Actually, when you work through the physics of it, weight in wheels is only microscopically more significant than weight on the "stationary" part of the bike. And several authorities assert that double-butted spokes are more durable (due to being more resilient) than straight-gauge spokes. – Daniel R Hicks Dec 21 '11 at 22:25
  • Hmmm, while I'm not sure of the physics calculations of it, I can relate the real world experience of riding one bike with 2 very different sets of wheels and feeling a fairly drastic difference. This was a much more noticeable difference than say having a full waterbottle or light system on the bicycle. Your results may vary. – DodgeDerek Dec 22 '11 at 1:22
  • I also would not disagree that the easier elongation of double butted spokes will contribute to some durability aspects of a wheel, but have seen in real life that spoke failure almost always occurs at the threads or head, places where butted spokes have undergone more stresses during manufacture. (Sorry for the double comment, still catching on to the finer details of this forum) – DodgeDerek Dec 22 '11 at 1:31
  • The idea with the double-butted spokes is that the spokes are heavy on the ends, where they need to be, and more flexible in the middle. The extra stress on the ends is present all the time, not just during manufacture. – Daniel R Hicks Dec 22 '11 at 3:37
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Besides the added hub and nipple weight, the rim would be weaker from the extra holes. Less holes in the rim, the stiffer the rim actually is. So less spokes is actually better. To a point of course. Even carbon tri spoke HED3 wheels are only a little lighter than a nice spoked wheel.

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