Why heavier gauge drive side spokes?



On Aug 8, 7:03 pm, Chris Nelson <[email protected]> wrote:
> Try using a hub such as DTSwiss where the left side flange is

closer
> to center than normal. This will cut down on wheel asymmetry and the
> resulting tension disparity mentioned by others.


That would be an easy thing for all hub manufacturers to do if it was
anything like a "fix". The narrow hub flanges help reduce slack spokes
due to radial loads, but at the expense of lateral stiffness, *and*
resistance to spokes going slack from lateral loads. IMO a 2 to 1
ratio in flange spacing and spoke tension (~18mm and 36mm), is about
the best with modern cassette widths.
 
Chalo wrote:
> [email protected] wrote:
>> I want to build a set of box rimmed, 32 hole, cross 3, 10 speed
>> wheels. What are the reasons for and advisability of using heavier,
>> e.g. 14/15/14 gauge, spokes on the rear drive side, as is often done?
>> Do I need to do this? I'm not a two kilowatt sprinter; I'd like to
>> use all 14/17/14's.

>
> On 10-speed rear hubs, the center-to-flange dimension on the right is
> about 1/3 of that on the left.


it's ~1/2, not 1/3. you can check out damon rinard's spoke calc
spreadsheet if you want to examine the tension ratio math.

> Roughly speaking, that means spoke
> tension must be three times higher on the right than it is on the
> left, and that side loads on the wheel have three times more
> mechanical advantage when they pull on right side spokes.
>
> There are two main reasons you shouldn't use 17ga spokes on the right
> side rear. First and foremost is that windup during building can
> limit the amount of tension that you can apply to right side spokes,
> and this in turn will require you to use less tension on the left.
> (Another r.b.t contributor reported favorable results from applying
> molybdenum disulfide lube to the spokes' threads to reduce windup.)
> Secondly, the thinner and stretchier 17ga spokes under high drive side
> tension will make your wheel more flexible under side loads,
> increasing the risk of bending your rim out of true or even collapsing
> your wheel.
>
> 1.8mm spokes have 44% more cross-sectional area than 1.5mm spokes.
> 2.0mm spokes have 78% more cross-sectional area. Since your drive
> side spokes are tensioned 3x higher than your left side spokes, it
> doesn't make sense for them to be the same gauge-- especially when
> that gauge is optimized for the lower-tension side.
>
> Chalo
>
 
On Aug 8, 7:05 pm, Paul Kopit <[email protected]> wrote:
> On Wed, 08 Aug 2007 02:21:31 -0700, [email protected] wrote:
> >I want to build a set of box rimmed, 32 hole, cross 3, 10 speed
> >wheels. What are the reasons for and advisability of using heavier,
> >e.g. 14/15/14 gauge, spokes on the rear drive side, as is often done?
> >Do I need to do this? I'm not a two kilowatt sprinter; I'd like to
> >use all 14/17/14's.

>
> Spokes that are that thin will twist when you try to put high enough
> tension on them. I find that problem even with DT revolution 2/1.5/2,
> especially on the drive side. I can build with 1.8/1.6/1.8.


The 14/17/14 gauge spokes that I was considering using exclusively are
the same DT revolution 2.0/1.5/2.0 mm spokes that you apparently have
used and experienced some DS windup with. (Probably it would have been
better if I had designated them as 2.0/1.5/2.0 mm spokes to begin
with.) I'm not trying to knock out, on a commercial basis, a pair of
very good and well built wheels in a couple of hours. I have the time
to deal with the windup and to enjoy the whole building process.

--

Spike
Sounds like you want to go ahead.
Other ways to gain on the spoke support angle for the DS is to use off center spoke holes in the rim such as Velocity Aerohead OC and high-low flanged hub such as White Industries H1.
I just completed a build with that combination, but I still convinced the rider that 14/15 DB on the DS was a better solution because one of his reasons for the new wheels was improved stiffness.
 
On Aug 8, 9:09 am, [email protected] wrote:
> On Aug 8, 7:34 am, Art Harris <[email protected]> wrote:
>
> > "Spike" wrote:
> > > I want to build a set of box rimmed, 32 hole, cross 3, 10 speed
> > > wheels. What are the reasons for and advisability of using heavier,
> > > e.g. 14/15/14 gauge, spokes on the rear drive side, as is often done?
> > > Do I need to do this? I'm not a two kilowatt sprinter; I'd like to
> > > use all 14/17/14's.

>
> snip
>
> > What do you expect to gain by using 14/17/14 spokes?

>
> > Art Harris

>
> The 14/17/14 gauge spokes are what I have at hand and by using only
> 14/17/14 spokes one obtains not only greater aesthetics but also the
> elegance of simplicity. If 14/17/14 spokes have sufficient physicals
> and workability for front wheel use, then one might think that they
> would also be suitable for rear wheels.


That doesn't follow at all. The reverse is true(what works for the
rear will work for the front) but the stresses in the rear are much
greater than the front.

Although their tensile
> strength is less than 14/15/14 spokes, isn't it still mush greater
> than required? Maybe I should have asked what does one expect to gain
> by using 14/15/14 spokes on the rear drive side -- windup aside --
> that isn't provided by using 14/17/14 spokes?


A more reliable wheel, all things being equal..hub/rim wise.
 
On Aug 8, 10:54 am, Nate Knutson <[email protected]> wrote:
> > Secondly, the thinner and stretchier 17ga spokes under high drive side
> > tension will make your wheel more flexible under side loads,
> > increasing the risk of bending your rim out of true or even collapsing
> > your wheel.

>
> Could you elaborate more on this? Not arguing, but I'm failing to grok


ahhhhh,'Stranger in a strange land"..great book....


> how this can be true, or how it can be so different for a 1.5 versus a
> 1.8 spoke, when all the wires we ride on are pretty darn flexy and
> also there have been perfectly ridable wheels with highly elastic
> spoke materials, like Spinergy. Is the flexibility of the spoke really
> that relevant in terms of supporting side loads, compared to the
> bracing angle and the tension?
 
On Aug 9, 6:14 am, daveornee <daveornee.2v1...@no-
mx.forums.cyclingforums.com> wrote:
> Other ways to gain on the spoke support angle for the DS is to use off
> center spoke holes in the rim such as Velocity Aerohead OC and high-low
> flanged hub such as White Industries H1.
> I just completed a build with that combination, but I still convinced
> the rider that 14/15 DB on the DS was a better solution because one of
> his reasons for the new wheels was improved stiffness.


The gain in bracing angle from the high flange is super tiny. You
don't get much stiffness improvement from having fatter spokes on the
drive side either, since the lateral stiffness comes mostly from the
NDS. If you are thinking of torque windup though, then a taller flange
and stiffer spokes on the DS will both help. The offset rim gives you
more even tension, but the lateral stiffness end up being a little
less than a symetrical rim.
 
Ron Ruff said:
On Aug 9, 6:14 am, daveornee <daveornee.2v1...@no-
mx.forums.cyclingforums.com> wrote:
> Other ways to gain on the spoke support angle for the DS is to use off
> center spoke holes in the rim such as Velocity Aerohead OC and high-low
> flanged hub such as White Industries H1.
> I just completed a build with that combination, but I still convinced
> the rider that 14/15 DB on the DS was a better solution because one of
> his reasons for the new wheels was improved stiffness.


The gain in bracing angle from the high flange is super tiny. You
don't get much stiffness improvement from having fatter spokes on the
drive side either, since the lateral stiffness comes mostly from the
NDS. If you are thinking of torque windup though, then a taller flange
and stiffer spokes on the DS will both help. The offset rim gives you
more even tension, but the lateral stiffness end up being a little
less than a symetrical rim.
All the differences I mentioned are "super tiny".
The lateral stiffness from higher flange is aided by two "super tiny" contibutions: higher spoke support angle & shorter spokes.
Most rear wheels have approximately 5% lower lateral stiffness from pushing the right side leftward Vs pushing the left side rightward. My goals in using higher right side flange, thicker spokes, and offset spoke bed is to reduce the spoke tension difference right to left as well as reduce the difference in lateral deflection for the same applied force.
Since you can't separate dynamic forces operating on a rear wheel in use, reducing torque windup will wheel operation as well.
When you say "lateral stiffness end up being a little less than a symetrical rim", how does this rate in terms of "super tiny"?
 
On Aug 8, 4:21 am, [email protected] wrote:
> I want to build a set of box rimmed, 32 hole, cross 3, 10 speed
> wheels. What are the reasons for and advisability of using heavier,
> e.g. 14/15/14 gauge, spokes on the rear drive side, as is often done?
> Do I need to do this? I'm not a two kilowatt sprinter; I'd like to
> use all 14/17/14's.
>
> Any and all comments will be appreciated -- except from that one
> disruptive and often in error, orifice of RBT, oracle of RBT
> wannabe, 'even if they don't know, i know their spokes are ground and
> polished, guy.
>
> --
>
> Spike


Thanks all -- well most all -- for the input. I'll mull it over and
investigate further while building up the front wheel and will likely
end up getting some 14/15/14 gauge spokes to use for the rear wheel
drive side. It can't hurt; screw the perceived aesthetics and
elegance of using all 14/17/14 gauge spokes if it's at the cost of not
producing a good wheel.

----

Spike
 
[email protected] wrote:
> On Aug 8, 4:21 am, [email protected] wrote:
>> I want to build a set of box rimmed, 32 hole, cross 3, 10 speed
>> wheels. What are the reasons for and advisability of using heavier,
>> e.g. 14/15/14 gauge, spokes on the rear drive side, as is often done?
>> Do I need to do this? I'm not a two kilowatt sprinter; I'd like to
>> use all 14/17/14's.
>>
>> Any and all comments will be appreciated -- except from that one
>> disruptive and often in error, orifice of RBT, oracle of RBT
>> wannabe, 'even if they don't know, i know their spokes are ground and
>> polished, guy.
>>
>> --
>>
>> Spike

>
> Thanks all -- well most all -- for the input. I'll mull it over and
> investigate further while building up the front wheel and will likely
> end up getting some 14/15/14 gauge spokes to use for the rear wheel
> drive side. It can't hurt; screw the perceived aesthetics and
> elegance of using all 14/17/14 gauge spokes if it's at the cost of not
> producing a good wheel.
>
> ----
>
> Spike
>
>


wow, did that hurt?