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When a wheel is built with j-bend spokes, they are typically "interlaced", as the picture from ParkTool shows (crossing #3): Interlacing picture by ParkTool

There are clear technical advantages of doing so, described in Jobst Brandt's "The Bicycle Wheel" and asked here previously.

But I have never seen straightpull spokes being interlaced. As a random example, here's a picture of a Shimano straightpull wheel not interlaced:

Shimano straightpull wheel

Is there a reason for this? I don't see how straightpull spokes/hubs are different in this respect, and IMO the same advantages of interlacing would apply.

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  • On my DT Swiss PR 1400 DICUT® OXiC rear wheel the spokes are interleaved and creaking like hell. I had to put tape between the spoke crossings to silence them. I checked the tension, it’s ~1200N on the drive side, so high enough. I think they are only barely touching (compared to a traditional 3 crossing J-bend wheel) which makes it worse.
    – Michael
    Jan 29 at 10:28

1 Answer 1

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I think straight-pull spokes don't have a problem with negative loads the same way j-bend spokes do.

For j-bend spokes, any push-force incurred by rim flex would force a non-interlaced spoke into substantial buckling and twisting. It is substantial because if the spoke started out perfectly straight, there is initially no direction it could move to take up any approach of the nipple towards the hub, the spoke first needs to deform into a new buckle that can then start to take up the slack. Juhist's answer discusses this in some more mathematical detail.

It is this motion that causes the nipples to loosen. Interlacing "solves" the problem by forcing every spoke into a little pre-buckle, which gives them a well-defined direction into which to deform when slack needs to be taken up. It's a big ugly hack, but it mostly avoids twisting that would unscrew the nipple.

Straigh-pull spokes solve the problem in a much better way: they allow the spokes to simply move inwards at the hub when necessary (in a way the j-bend prevents, counter-productively). Movement at the hub is harmless as there's no screwed thread at that end.
As a secondary advantage, the perfectly straight spokes make the wheel stiffer by way of being more rigid in the tensile direction, which prevents the wheel from flexing as much in the first place.

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  • The linked answer explains only mitigating a spoke going completely slack. This fully applies to straightpull spokes as well, they better not go slack because of the same reasons. No reasonably tightened wheel ever goes so far as to buckle and twist the spokes. Jan 28 at 16:02
  • @KonstantinShemyak look at super-SloMo footage of MTB and you'll see that spoke buckling totally is a thing. Shouldn't happen on smooth tarmac, but can certainly happen on an ordinary pothole or similar. Basically, as soon as you get to the no-tension state it's inevitable, because the modulus drops down dramatically as the loading changes from tensile to compressive. Jan 28 at 16:12
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    I'd like to see such video. There are straightpull hubs (e.g. ones used in Mavic Ksyrium, mavic.com/en-us/p/ksyrium-sl-disc-rr1244?variant=262) which would just release the spoke which is about to bulge. Jan 28 at 16:32
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    I don't see spokes bulging in the linked video. Jan 28 at 19:04
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    @KonstantinShemyak I have a pair of Mavic Allroad UST (the entry-level to the range), they have straightpull spokes and there is a contact. I also have have a pair of Allroad S (second tier), that features the same hub/design as the Ksyrium SL you linked. DT Swiss on the other hand seems to have interlacing on all their range (example from a high end XC wheel dtswiss.com/itc/00/00/00/00/00/00/00/00/70/00/11/25/8/…) So hard from that sample to draw conclusions.
    – Rеnаud
    Jan 29 at 13:20

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