Cycling UK Forum

I am interested in how some spoke nipples have a hex, square or Torx head that sits hidden, inside the rim.

But, what point?

Okay, so no scratches on the exposed part of the nipples, like if you are using coloured nipples, eg. black.

But is building easier than with regular/slotted spokes? Guess you can use a little driver bit in a cordless screwdriver, like what DT sell.

And how about building by machine? Is that what 'double ended' spokes are really meant for?

According to Gerd Schraner in his book, the art of wheelbuilding, nipples with hexagonal heads were designed to achieve a higher spoke tension for use in wheels with deep V section rims. He quotes a conventional brass brass nipple as being able to achieve a spoke tension of 1200 N and a hex head nipple being able to achieve a tension of 2000 N. Not sure the same would apply to a nipple with a Torx head.
Steve

Wheelbuilding machines drive the nipples from the end, ie. inside the rim.
Also any damage to the nipple finish will be invisible.

With normal nipples, if the threads are lubricated and you use a good 4-sided spoke wrench, you can get the spokes as tight as they ever need to be, and certainly tighter than the rim can take. 200kgf is possible.

I have seen several machine-built wheels with marks that strongly suggest that the machine did not always drive the nipples via the slot as intended, I have always supposed that alternative nipple designs were to make machine building easier/better. IIRC Peugeot used to sell bikes with hexagon-headed nipples in them, and they were always built very (too?) tightly, by machine, I thought.

200 kgf is about 1,960 N.

Jonathan

I have a wheel that is 170kgf on one side. Wheelbuilding is often a compromise as rim manufacturers tend to specify an improbably low max tension, meaning you have to ignore it to maintain tension on the LH side of a heavily dished wheel. The tension ratio in a Shimano 11 speed road hub is 1:0.45. 76kgf on the slacker side is only just enough.

rogerzilla wrote: ↑17 Dec 2023, 8:43pm I have a wheel that is 170kgf on one side. Wheelbuilding is often a compromise as rim manufacturers tend to specify an improbably low max tension, meaning you have to ignore it to maintain tension on the LH side of a heavily dished wheel. The tension ratio in a Shimano 11 speed road hub is 1:0.45. 76kgf on the slacker side is only just enough.

It no longer surprises me when fashion pushes the engineering to such absurdities

When building wheels with blade spokes I use the DT Swiss Squorx (Torx head) nipples and the Squorx driver, which means there is no spoke key to interfere with using a slotted tool to hold the end of the bladed section of the spoke to prevent wind-up.

NickJP wrote: ↑18 Dec 2023, 4:28am When building wheels with blade spokes I use the DT Swiss Squorx (Torx head) nipples and the Squorx driver, which means there is no spoke key to interfere with using a slotted tool to hold the end of the bladed section of the spoke to prevent wind-up.

That should work.
Sapim( I think) used to have on their website a comparison of how many fatigue cycles their various spokes would last before failing, on a test rig.
The cynic in me wonders if the outstanding performance of their bladed spokes in this test was because the spokes flexed in the blade rather than at the elbow.
Bladed spokes are something I have never tried.

A local bike shop mechanic and MTB downhiller swore by Sapim CX-Ray spokes for the hardest possible use. Something to do with material and consistent quality rather than the dubious aero advantage. They are frighteningly expensive.

I think the spokes are all the same material. Working the material to a blade shape won’t change the properties of the wire at the elbow, which is why I wonder if the flat spokes flex where flat not at the elbow

i think you might be right about that. My DIY aero.spokes may share a similar advantage, but since it felt like casting pearls before swine, I somehow doubt that anyone else will ever find this out.

531colin wrote: ↑18 Dec 2023, 2:21pmI think the spokes are all the same material. Working the material to a blade shape won’t change the properties of the wire at the elbow, which is why I wonder if the flat spokes flex where flat not at the elbow

I would say that's the reason Sapim claim the CX-Ray as having the longest fatigue life of any of their spokes. The minimal amount of material along the bladed section of the spoke (only 2.2 x 0.9mm) means that cyclic stress of the spokes causes greater elongation of the straight section and less flex of the elbow, compared to round plain gauge or butted spokes.

Hadn’t checked the dimensions; assumed the blades were just 2.8mm wire flattened!