SAPIM Spoke FAtigue Estimate

[Johan Bornman]

On Feb 12,> Johan Bornman wrote:
> > > Jim, I don't understand your "offset" concept. The fact that the spoke
> > comes out of the flange 3mm (or whatever) off centre from the flange,
> > doesn't mean it cannot still follow a straight line to the rim (slight
> > detour at cross-over negated). We're talking about a straight line
> > here, essentially from the elbow's exit point to the nipple. Where is
> > the bending in that?
> Jim wrote:

> it's all about the offset johan. one end is not loaded axially to the
> spoke.- Hide quoted text -
>
OK, what I find confusing is that you suggest the offset is 3mm -
presumably the length of the elbow. However, the innermost anchor
point for the spoke is the elbow bend. Further, this bend is forced
into the softer hub and flush. Therefore the offset is only half the
spoke diameter, at most 1mm. However, I don't see that as offset
because there is no room there for bending. I see it more as a biased
anchor point where the spoke is anchored to the hub with a bias
towards the inner elbow side. Visualise it as a 300mm flat ruler under
tension between the thumb and forefingers of your two hands. However,
on the one side you're not pinching it in the centre, but in the
corner.

JB

 

[Johan Bornman]

On Feb 12, 5:10 pm, jim beam <[email protected]> wrote:
>
> > On Feb 9, 9:43 pm, jim beam <[email protected]> wrote:
> >> hold on a second. if you go to buy a spoke from your lbs, what do you
> >> receive? chances are, it's a spoke made by d.t., wheelsmith or sapim.
> >> all are well made, utilize very high quality materials, and their use
> >> has a significant impact on fatigue results.
>
> > Johan Bornman asked: How does their use have a significant impact on fatigue results. A
> > cycle is a cycle. Are you suggesting that abuse of wheels has an
> > impact on fatigue failures? Please explain, I don't understand "use"
> > in this context.
>
> Jim Replied: a number of factors affect fatigue - these include design, material
> quality and surface finish. with a quality branded spoke, all 3 bases
> are covered.
>
>
> Johan now asks: You still haven't explained "use". I understand that a number of factors affect fatigue, but explain "use".

 

[jim beam]

Johan Bornman wrote:
> On Feb 12, 5:10 pm, jim beam <[email protected]> wrote:
>>> On Feb 9, 9:43 pm, jim beam <[email protected]> wrote:
>>>> hold on a second. if you go to buy a spoke from your lbs, what do you
>>>> receive? chances are, it's a spoke made by d.t., wheelsmith or sapim.
>>>> all are well made, utilize very high quality materials, and their use
>>>> has a significant impact on fatigue results.
>>> Johan Bornman asked: How does their use have a significant impact on fatigue results. A
>>> cycle is a cycle. Are you suggesting that abuse of wheels has an
>>> impact on fatigue failures? Please explain, I don't understand "use"
>>> in this context.
>> Jim Replied: a number of factors affect fatigue - these include design, material
>> quality and surface finish. with a quality branded spoke, all 3 bases
>> are covered.
>>
>>
>> Johan now asks: You still haven't explained "use". I understand that a number of factors affect fatigue, but explain "use".
>
deployment. utilization. "use" of good materials improves fatigue
performance.