Asymmetric Rims, did I get it right?

shrpshtr325

Infinite Source of Sarcasm
Team MTBNJ Halter's
Correct, there should be no shear stress on a spoke, (well except when that stick gets stuck in the wheel). Have you ever seen how rolled threads are made? they are actually deforming the metal into the shape of the threads, this is a stressor on the material as well and is stress hardening that section of the material, making it stronger (granted a bit more brittle as well). The theory still holds that the weak spot is the transition between the threads and the 'shoulder' when loaded in tension, there is no undercut or stress relief at that intersection to mitigate the stress riser, do the first thread concentrates the stress and thats where they are prone to failure (at the spoke end at least). The change in material properties from the stress hardening is also working against the you in this case since the two areas of the spoke will behave differently under load and deform at different rates.

keep in mind also that while rolled threads make the major diameter a hair bigger (im not sure if .2mm is correct, but lets run with it) it is still creating a minor diameter when it forces that material out, that minor diameter (lets call it -.2 assuming that the material that is moved all goes out) is still the weak spot in tension, the smallest area is where the failure if prone to happening (assuming no material defects are present)
 

Karate Monkey

Well-Known Member
I didn't think anyone would be this interested in the minutiae (other than me, appreciating an 'elegant' system). It is 2.2mm (nominally), and the valleys/peaks of the spoke are not particularly sharp. When spokes break at the threads, they break at the transition from wire stock to threads, 99/100 at the 'first' thread (so, the transition from wire size to thread size).

And yes, I've not only watched them made, but done it myself; the Hozan spoke threader uses a rolling head (Phil/Morizumi/Kowa/industrial machines [DT, Wheelsmith, Alpina, Chung Nan, et. al] use flat dies that move across each other). The head on the Hozan/clearance on the other machines is adjustable, and since the spoke doesn't gain length during rolling, I'm (personally) forced to conclude that material is pushed up/down. The rolling heads use a tapered lead-in to begin the threading (so, you can tell if a bike shop cut a spoke to size: rather than a crisp delineation, there will be a vague 'ghosting' of threads ~.5mm long).

We may be having a difference of nomenclature; I'm vaguely aware that the 'shoulder' of a bolt is the area between head/shaft (heh). The failure on spoke nipples is almost always the head being popped off (so, the thing that is allowing tension to be put on it). I don't believe there is enough material to support a relief there (there is a fillet on good quality nipples, that serves the double purpose of aligning the nipple to the spoke/hub, and relieving stress).
 

shrpshtr325

Infinite Source of Sarcasm
Team MTBNJ Halter's
the shoulder of a shoulder bolt is the smooth (non-threaded) section between the threads and the head. (the 'shaft' portion of the shoulder bolt)

Yes we are talking about the same failure area (the first thread or so from wire stock ('shoulder')to thread. this is where the stress concentrates as it is where the diameter is abruptly changing, even if they roll spoke threads with a taper (which would make them awfully sloppy) there would still be a stress riser at this point.


p.s. forgot about this from one of your earlier posts, all threads in the spoke nipple are cut (tapped) as there is no way (that im aware of at least) to roll an internal thread.
 

Steve Vai

Endurance Guy: Tolerates most of us.
This is an amazing discussion about a part that seldom results in a broken wheel without the one piece of the puzzle no one has brought up, corrosion. Which trumps whatever the nipple threads are doing.
 

Karate Monkey

Well-Known Member
This is an amazing discussion about a part that seldom results in a broken wheel without the one piece of the puzzle no one has brought up, corrosion. Which trumps whatever the nipple threads are doing.

I mean, I'm waiting for my doctors appointment for my back. Can't ride, can't really do house work.

I suppose I could go wash my bike wheels off, but...
 

serviceguy

Well-Known Member
I was about to have my quality time with my new soon to be wheels and could not determine if the rims are drilled right handed or left handed, the holes seem all perfectly aligned with the valve hole. The only pictures of these rims (WTB Asym i35) that I found online show a wheelset built with one rim laced as right handed and the other one as left handed so now I'm wondering if that has anything to do with them being oriented in opposite sides...I did contact WTB but I'm not holding my breath waiting to hear from them during the weekend and I really would like to get these wheels built by tomorrow...so here I am overthinking an easy matter once again!
 

serviceguy

Well-Known Member
1) put rim on table.

2) measure from table top to consecutive holes.
Duh moment...thanks!

And...inconclusive, the eyelets distance from the edge of the rim is within 2/100 of a mm after measuring 5 off them on a glass table. Is it possible they're all centered on the same ideal line passing through the center of the valve hole?
 
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Karate Monkey

Well-Known Member
Duh moment...thanks!

And...inconclusive, the eyelets distance from the edge of the rim is within 2/100 of a mm after measuring 5 off them on a glass table. Is it possible they're all centered on the same ideal line passing through the center of the valve hole?

Entirely. And if they're eyeleted, it doesn't matter which way you go...that only matters if you have a rim with no eyelets that is drilled for specific angles.
 

serviceguy

Well-Known Member
Entirely. And if they're eyeleted, it doesn't matter which way you go...that only matters if you have a rim with no eyelets that is drilled for specific angles.
This seems to be an issue ( or a non issue) specifically with WTB rims, the previous set that I laced used KOM Though rims and the 4D drilling wasn’t that obvioys to guess either.
 

Karate Monkey

Well-Known Member
This seems to be an issue ( or a non issue) specifically with WTB rims, the previous set that I laced used KOM Though rims and the 4D drilling wasn’t that obvioys to guess either.

Drop a nipple through the hole. It'll point left/right, if the rim is drilled on an angle.
 
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