Half radial spoking and the new Dura-Ace wheels



jim beam <[email protected]> wrote in message news:<[email protected]>...
> David L. Johnson wrote:
> > On Thu, 15 Jul 2004 00:27:17 -0700, John McGraw wrote:
> >
> >
> >>Why them ain't no cracks on the Rolf wheels. Rims can only crack when
> >>they are hard anodized. You do not have to belive me. Just Google this
> >>groups archives on the subject & Jobsts posts in particular ;-). In
> >>reality I am far from convinced that all hard anodizing causes cracks
> >>& that non anodized rims almost never crack, which is what Jobst has
> >>implied for years, sometimes going so far to state that any anodizing
> >>causes rims to crack. John

> >
> >
> > In fairness to Jobst, who seems to be off somewhere right now (or at
> > least off on a different thread), saying that hard anodizing causes
> > cracks is not the same as saying that a non-anodized rim will not crack.
> > It is certainly true that non-anodized rims can crack, but that takes
> > nothing away from his observation that anodized rims are more likely to do
> > so.
> >

>
> unfortunately, that "observation" is flawed. i've examined a number of
> cracked anodized rims, and while it is possible for cracked anodizing to
> initiate fatigue, it's not been the cause of any of the cracking i've
> seen. jobst may have ranted on about it for years but it does not mean
> he knew what he was looking at or that he'd done his "analysis" correctly.
>
> fact: anodizing is present on the majority of the rims frequently cited
> here as "unanodized".
> fact: anodizing protects against more serious flaws that cause premature
> failure like pitting & corrosion. that's why it's done.



And your qualifications to be making these observations are?
 
On 2004-07-16 05:59:30 -0700, [email protected] (Qui si parla
Campagnolo ) said:

> Bill-<< Good God Peter, are you still riding 6 speed wheels on a regular basis?
>>> <BR><BR>

>
> yessir, I am but a 7s freewheel, downtube friction shifters, I see no need for
> anything more modern.


Man, you *are* a retro grouch ;-)

I'd avoid that stuff, simply because replacement parts are more
expensive than they are for the newer stuff.

I'll bet your shop partner is running 10 speed by now, eh?
 
Bill-<< Man, you *are* a retro grouch ;-) >><BR><BR>

AND DON'T YOU FORGET IT!!!

Bill<< I'd avoid that stuff, simply because replacement parts are more
expensive than they are for the newer stuff. >><BR><BR>

I have many replacement parts in my garage, freewheels, hubsets, rear ders,
BBs, etc. The stuff will last far longer than i will.


<Bill< I'll bet your shop partner is running 10 speed by now, eh? >><BR><BR>

Yep, but he's racing.


Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"
 
Ritch wrote:
> Sheldon's site, http://www.sheldonbrown.com/wheelbuild.html#half-radial
> says semi-tangent spokes on the right side (drive side) and radial
> spokes on the left side (NDS) can make highly dished rear wheels more
> durable.
>
> Look at the 2005 Dura-Ace wheels,
> http://www.cyclingnews.com/photos/2004/tour04/tech/?id=jul13/WH-7800-carbon-hub
> and it looks like radial on the right and semi-tangent on the left.
>
> Has Shimano got it the wrong way around, or does Sheldon's page need
> correction? Perhaps and engineer/wheel expert can shed some light...


Doing it Shimano's way can even out the spoke tensions. The hub has to
be strong enough to carry virtually all the torque across the shell to
the LH flange though. I guess they've worked it out.
 
rothgar-<< Doing it Shimano's way can even out the spoke tensions. >><BR><BR>

Not exactly. Building a wheel 1/2 radial left side, 1/2 radial right side, all
radial or all cross, for a true round tensioned and dished wheel, the spoke
tension would be the same in all cases. The ONLY way to 'equalize' spoke
tensions on a rear is to move the spoke holes over(ala OCR rims) or move the
left flange toward the right.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"
 
Qui si parla Campagnolo wrote:
> rothgar-<< Doing it Shimano's way can even out the spoke tensions. >><BR><BR>
>
> Not exactly. Building a wheel 1/2 radial left side, 1/2 radial right side, all
> radial or all cross, for a true round tensioned and dished wheel, the spoke
> tension would be the same in all cases. The ONLY way to 'equalize' spoke
> tensions on a rear is to move the spoke holes over(ala OCR rims) or move the
> left flange toward the right.


the shimano 7700 wheel is actually pretty close to even tension, on 4 of
the non-drive side spokes at least. it's a function of the funky
left/right crossover spoke design - it maximizes the bracing angle, the
determinant of tension differential.
 
Qui si parla Campagnolo wrote:

> rothgar-<< Doing it Shimano's way can even out the spoke tensions. >><BR><BR>
>
> Not exactly. Building a wheel 1/2 radial left side, 1/2 radial right side, all
> radial or all cross, for a true round tensioned and dished wheel, the spoke
> tension would be the same in all cases. The ONLY way to 'equalize' spoke
> tensions on a rear is to move the spoke holes over(ala OCR rims) or move the
> left flange toward the right.


There is another way to get equal spoke tension with regular hubs and
rims. Build the wheel with no dish and use offset chainstays to
compensate for the rim not being centered with the hub. This was done by
ATP Vision (while they were still in business).

--
Tom Sherman – Quad City Area
 
jim-<< the shimano 7700 wheel is actually pretty close to even tension, on 4 of

the non-drive side spokes at least >><BR><BR>

Mostly because the center to flange on the left equals the right.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"