Question about aero pokes and nipples

[Carl Sundquist]

I've been under the impression that elliptical spokes (which usually start
out as 15g) are more aero than bladed spokes (which are usually flattened
14g). Ignorant or not?

How does the tensile strength of aluminum nipples compare to brass? Is
aluminum more prone to breakage from thread stripping or the nipple heads
popping off?

 

[Qui si parla Campagnolo]

Carl Sundquist wrote:
> I've been under the impression that elliptical spokes (which usually start
> out as 15g) are more aero than bladed spokes (which are usually flattened
> 14g). Ignorant or not?
>
> How does the tensile strength of aluminum nipples compare to brass? Is
> aluminum more prone to breakage from thread stripping or the nipple heads
> popping off?

The biggest advantage for 15g aero or oval spokes is that you don't
need to slot the hub. The aero differences are probably teeny.

As for brass nipps, they should be used in all instances afai
concerned. Aluminum nipps bring almost nothing to the table and are far
more prone to deformation and failure during use.

 

[jtaylor]

"Carl Sundquist" <[email protected]> wrote in message
news:MQ_ef.19407$4l5.7759@dukeread05...
> I've been under the impression that elliptical spokes (which usually start
> out as 15g) are more aero than bladed spokes (which are usually flattened
> 14g). Ignorant or not?
>

If there is a difference, it is most likely so small that it is not worth
worrying about.

> How does the tensile strength of aluminum nipples compare to brass?

It depends, of course on the alloy(s) used, but in general, brasses are
anywhere from about 45 to 85 ksi, and aluminium alloys range from about 15
to 60 ksi. Aluminium can be heat-treated (so can brass, but such treatment
only reduces brass' strength). Brass is a (much) better material for spoke
nipples because it is less likely to corrode and freeze to the steel spoke.
The difference in weight between 72 brass nipples and 72 aluminium nipples
is _also_ not worth worrying about.

> Is
> aluminum more prone to breakage from thread stripping or the nipple heads
> popping off?
>

Again, it depends on the alloy, but experience says: Yup.

 

[Werehatrack]

On Thu, 17 Nov 2005 06:37:53 -0600, "Carl Sundquist" <[email protected]>
wrote:

>I've been under the impression that elliptical spokes (which usually start
>out as 15g) are more aero than bladed spokes (which are usually flattened
>14g). Ignorant or not?

If you're in the class of racing competitor for which this tiny
advantage might be relevant, the cost of the wind tunnel testing to
definitely answer the question is probably not beyond the realm of
feasibility. Otherwise, the difference is negligible, and is most
likely overshadowed by the fact that elliptical spokes can be
installed without having to slot the hub, as noted elsewhere.

>How does the tensile strength of aluminum nipples compare to brass?

On average, brass is stronger.

>Is
>aluminum more prone to breakage from thread stripping or the nipple heads
>popping off?

Both, and it's also much worse about siezing in place on the spoke.
--
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[John Forrest Tomlinson]

On Thu, 17 Nov 2005 19:25:06 GMT, Werehatrack
<[email protected]> wrote:

>On Thu, 17 Nov 2005 06:37:53 -0600, "Carl Sundquist" <[email protected]>
>wrote:
>
>>I've been under the impression that elliptical spokes (which usually start
>>out as 15g) are more aero than bladed spokes (which are usually flattened
>>14g). Ignorant or not?
>
>If you're in the class of racing competitor for which this tiny
>advantage might be relevant, the cost of the wind tunnel testing to
>definitely answer the question is probably not beyond the realm of
>feasibility.

Wind tunnel testing is expensive and not every Olympian and former
elite national champion and former elite world championship
participant (Carl Sundquist was all of these) has access to those
kinds of resources.

JT

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[Ron Ruff]

Carl Sundquist wrote:
> I've been under the impression that elliptical spokes (which usually start
> out as 15g) are more aero than bladed spokes (which are usually flattened
> 14g). Ignorant or not?
>
> How does the tensile strength of aluminum nipples compare to brass? Is
> aluminum more prone to breakage from thread stripping or the nipple heads
> popping off?

Zipp at least, claims that the oval spokes are slightly better. I would
expect this to be the case at higher wind angles... but I've also read
claims that a sharp leading edge is best (most blades and all oval
spokes have rounded edges).

All the oval spokes I've seen are butted (Wheelsmith, DT, Sapim), with
2.0 or 1.8 ends and 1.6 center sections that have been flattened into
an oval shape (like 2.2x1.2). This would be better in fatigue than a
straight 2.0 bladed spoke.

I think the Wheelsmith AE15 spokes are a really good value (60 cents
each online). They are 1.8/1.6 ovals.