bfd said:
Quoted message said:D'ohBoy said:
[email hidden] wrote:
> On 28 Jul 2006 08:38:20 -0700, "D'ohBoy" <[email hidden]> wrote:
>
> >
> >bfd wrote:
> >> "Richard Utt" <[email hidden]> wrote in message
> >> news:[email hidden]...
> >> > Peter White uses them on his wheels:
> >> > http://www.peterwhitecycles.com/spokes.asp
> >> >
> >> >
> >> Similarly, Mike Garcia of Oddsnendo wheels uses wheelsmith spokes too:
> >>
> >> http://oddsandendos.safeshopper.com/20/cat20.htm?987
> >>
> >> This is interesting. Wheelsmith spokes have always been held in high
> >> regards. I wonder whether this is a bad batch? I remember when there was a
> >> hoopla over the quality and consistency of DT spokes too.
> >
> >Interesting to note in the chart at the bottom of Mr. Garcia's page you
> >linked to that the 14/15 DB spokes are ~10% lower in stiffness
> >(relative to a 14ga spoke) than all the others.
> >
> >Hmmmmm......
> >
> >D'ohBoy
>
> Dear D'oh,
>
> There's nothing odd about the Wheelsmith spokes having a lower
> stiffness than the other brands on the chart.
>
> The stiffness, as the note at the bottom of the chart says, is
> calculated from the square of the diameter of the narrowest section.
>
> So the calculated stiffness must be less when the center span of the
> Wheelsmith spokes is narrower.
>
> Cheers,
>
> Carl Fogel
Carl:
Thanks for assuming I am an idiot. In this case, you are wrong. I was
referring to the THREE 14/15 SPOKES FROM DIFFERENT MANUFACTURERS SHOWN
IN THE CHART. OF WHICH, WHEN NORMALIZED TO A 14 GA NON-BUTTED SPOKES,
THE WHEELSMITH HAD ABOUT 10% LOWER RELATIVE STIFFNESS.
CHEERS BACK AT YA.
D'ohBoy, who tires of your smarmy "charm"
Dear D'oh,
It occurs to me that you may still be missing my point, so I'll spell
it out.
The center spans of what you're calling "14/15" gauge spokes are not
the same width:
spoke center stiffness vs 2.0
DT Swiss Competition 1.8 81%
WheelSmith DB14 1.7 72.25%
Sapim Race 1.8 81%
That's why the chart doesn't call the groups "14/15" gauge and
provides the actual dimensions.
Similar differences can be seen in other groups, even with two spoke
models from the same manufacturer.
I guess the question is does make any noticeable difference?
Dear BFD,
Probably not.
The chart itself, for example, puts same-dimension spokes into
different "groups"--the next "group" below the three that I listed
starts with a DT Swiss Supercomp, whose dimensions are 2.0 x 1.7 x
2.0, the same as the Wheelsmith in the middle of the previous group:
spoke center stiffness vs 2.0
DT Swiss Competition 1.8 81%
WheelSmith DB14 1.7 72.25%
Sapim Race 1.8 81%
[next "group"]
DT Swiss SuperComp 1.7 72.3%
http://oddsandendos.safeshopper.com/20/cat20.htm?987
Within "groups," the chart apparently sorts by spoke length, a
somewhat bizarre choice. The disparities in weight greatly exceed the
minor length differences and are probably due to the length of the
butted sections, which varies between manufacturers.
In terms of strength and elasticity, any 2.0 x 1.7 x 2.0 spoke is
likely to be the same as the others. They're pretty much the same kind
of stainless steel, no matter what secret alloys the makers claim.
Lower quality-control will lead to more fatigue failures, and a bad
batch of raw wire can lead to numerous fatigue failures, but a
straightforward stress-strain test will show roughly similar strengh
for similar diameters.
Interestingly, the spoke stress-strain tests in the back of "The
Bicycle Wheel" show almost identical curves for DT and Wheelsmith
unbutted spokes, suggesting identical material and cross-section.
But the Wheelsmith butted spokes fail noticeably earlier than the DT
butted spokes. Since it's unlikely that Wheelsmith used different
steel for butted spokes, this suggests that the Wheelsmith spokes may
have actually had the thinner center sections shown in the chart
above, 2.0 x 1.7 x 2.0 and 1.8 x 1.55 x 1.8, not the 2.0 x 1.8 x 2.0
and 1.8 x 1.6 x 1.6 of the other brands.
(Jobst's text mentions only 2.0 and 1.8 butted and unbutted, with no
measurement of the middle section diameter. The same tests appear in
the 2nd and 3rd edition, with the 3rd editon calling them swaged
instead of butted. The 1st edition tested DT, Union, and Robegel
stainless and non-stainless, with one butted spoke.)
Regardless of how thick the center sections actually were, the failure
points of the stress-strain curves for even the 1.8 butted Wheelsmith
spokes are well above ordinary spoke tension--200+ kg is comfortably
above the 70 to 150 kg range recommended by most manufacturers.
The slightly thinner midsection will make a Wheelsmith spoke a little
easier to twist, making it harder to true the wheel, but it will be a
little "stretchier," which is usually considered a good thing. It
won't fail under ordinary tension.
Peter Chisholm has often mentioned his stretched Wheelsmith spokes,
but I suspect that they were probably just a bad batch. I don't know
of anyone who claims that Wheelsmith spokes normally stretch in that
fashion.
Certainly the complaints about Wheelsmith based on a few spokes from
years ago pale in comparison to this:
January 8, 2006
Widespread Spoke Failures
Bike shops are being forced to build hundreds of replacement wheels
each week because spokes in stock wheels are failing. The problem is
currently found in bikes costing up to $600 from makers such as Fuji,
Giant, Jamis, Pacific Cycle, Raleigh, Specialized, Trek and others.
The scope of the problem is still uncertain, according to a cover
story in the trade magazine, Bicycle Retailer & Industry News. Bikes
made for the above companies in various Chinese assembly plants
received wheels laced with defective spokes.
The spokes are breaking in the middle and/or rusting. It's suspected
that cost-cutting by a Korean company resulted in substandard wire
being supplied to spoke manufacturers. According to the magazine,
tests show that the spokes have nickel and molybdenum contents far
below normal levels.
The faulty spokes may have N, Z or S stamped into the round head or no
insignia at all. If you have a 2004 or '05 bike in which the spokes
begin rusting or breaking, check with the shop where you bought it.
http://www.climbonline.org/news/recalls.shtml
Cheers,
Carl Fogel