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Straight spokes will have the same diameter through the whole length, double butted spoked are thinner in the middle than at the ends. Here's my current understanding of the benefits of each:

Double Butted Spokes

  1. Lighter than Straight Spokes
  2. More elasticity in the wheel (less rigid / will flex some before breaking)
  3. Spokes will bow out less at the crossings
  4. Easier to bend/lace
  5. When overtightened or stressed too hard, the spoke is more likely to snap than the rim eyelets or the hub's flange

Straight Spokes

  1. Stronger than butted spokes
  2. Less elasticity in the wheel (more rigid / may break before flexing)
  3. More available at bike shops
  4. Cheaper

What are other reasons to use one over the other, or more pros/cons that may influence one's decision to use one over the other when hand building wheels? ('Straight spokes are easier to machine lace' may be true, for example, but doesn't help me decide which to order)

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  • You pretty much said everything. I don't think elasticity would be significantly different on butted spokes: I think the main reason for butting is 90% weight saving and 10% aerodynamics, more or less. Also, the very neck on butted spokes might be itself a stress-raiser and become a weak point in the spoke.
    – heltonbiker
    Commented Apr 3, 2012 at 17:04
  • Sort of covered by "more available/cheaper", but: butted spokes are available in a fixed range of sizes. If you have an obscure wheel size or lacing pattern, you[1] can always cut down a longer plain spoke and rethread it, but there are limits to doing that with a butted spoke. [1] Or at least a local bike shop with a spoke threading machine: billys.co.uk/english/group.php?prod=2CY07836
    – armb
    Commented Mar 22, 2013 at 10:25

3 Answers 3

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In his book 'The bicycle wheel' Jobst Brandt, says that double butted spokes will be more resistant to fatigue failure when built into a wheel.

This is because spokes break because of the cyclic stress they suffer as the wheel rotates.

As the spoke rotates thru the bottom of the wheel it experiences a reduction in tension.

Butted spokes are more elastic so this reduction in tension is spread over more spokes, each experiencing a smaller reduction in tension.

Wheels are an order of magnitude stiffer than the tyres they roll on, so any stiffness differences will not be noticeable. A wheel built with butted spokes will be able to carry a heavier load before any of the spokes become slack. At this point the rim is no longer restrained and the wheel will be more likely to collapse.

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  • Yes, I've read several claims that double-butted spokes are superior because they concentrate the strain (vs stess) in the straight part of the spoke rather then the ends.
    – Daniel R Hicks
    Commented Apr 5, 2012 at 15:44
  • "Butted spokes are more elastic so this reduction in tension is spread over more spokes, each experiencing a smaller reduction in tension." - No. This is only a factor of increasing the number of spokes; it is completely independent of spoke type.
    – Phil Willoughby
    Commented Feb 2, 2015 at 20:52
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    Its a factor of the relative stiffness of rims and spokes. A stiff rim, stretchy spokes will spread the deformation over a larger number of spokes than a bendy rim, with stiff spokes.
    – Andy Morris
    Commented Feb 13, 2015 at 13:33
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Plain-gauge (PG) spokes will break at the shoulder (where they leave the hub) due to metal fatigue at some point during the life of the wheel. Varying the tension in a PG spoke tends to vary the amount of bend at the shoulder; varying the tension in a double-butted (DB) spoke tends to vary the length of the thinner section, which is much better from a fatigue perspective.

There is no feel difference between 2.0mm-straight spokes, 2.0/1.8 DB-spokes and 2.0/1.5 DB-spokes at the same tension with the same rim. Source: I built them and rode them.

There is no load-carrying difference between DB spokes and PG spokes either. Load-bearing capacity is a function of the spoke tension and the spoke count. If you take a look at the spoke specs of at least DT Swiss and Sapim spokes you will find that the DB spokes will take the same tension as (and often more than) their PG counterparts.

The other option to consider is bladed spokes like the Sapim CX-Ray, which are basically DB spokes with the thinner section pressed flat. This has some nontrivial aerodynamic benefit and is also a bit easier to build with because you can hold the spoke straight: no need to worry about spoke wind-up.

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You have to be a lot more careful about windup in butted spokes. You have to detension each spoke more carefully when building by turning a bit extra and turning back. Otherwise they might re adjust themselves. I think 14g can carry a heavier load than DB.

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