vittore30

Really? Like here: Campagnolo Chorus 9 Speed Hubs Laced Fir Apollo Clinchers Wheels for Road Bike | eBay ?
same as mine: DS leading spokes heads in, NDS leading spokes heads out

rpenmanparker 

I'm having trouble finding support for my contention that stress relieving should be done before bringing the spokes up to full tension. I know Brandt syou won't hurt the spokes if you stress them after they are at full tension, because 120 kgf or so is only about 1/3 the tensile strength at yield of the spoke. But I worry more about the rim and hub. I wouldn't want to pull the nipple through the rim or crack the hub at the spoke hole by all that added tension during the relieving process. I know I saw that advice somewhere, I just can't lay my hands on it right now.

mooder

To OP, it was probably suggested but if not, always apply the same tension every where. Put half a turn every where by example, that way you know the tension is the same. Normally the wheel should be true but if it's not, adding a quarter turn will do the trick most of the time.

ThermionicScott 

On the contrary, one of the goals of Jobst's stress-relieving was/is to catch potential failures while building the wheel, rather than later on the road. You want to simulate the worst stress that all the parts will see before they see it.

That the practice also helps all the parts to settle into a sturdy, stable wheel is a nice side-benefit.

Jiggle

I've stress relieved 24 spoke wheels built with xr200s at full tension (120kgf) with no problem. If I put my 70kg/2 on each side of the rim, and the DS spoke angle is 4 degrees, then that is an additional 500kg of tension on each side. If that is divided between a spoke pair, then 250kg on each spoke. Still far below the spoke's ultimate strength, but quite a lot of stress on the spoke hole area for thin bedded rims.

Jiggle

Why did you choose 14g spokes? Were they cheaper that double butted spokes? This is ancillary to your original post. You should always use double butted spokes if it is possible to do so.

Jiggle

Because (they say) after the trailing spoke crosses a leading spoke, the effective flange diameter spacing is increased. You can see they did that in the pics.

andr0id

So, over the years I've changed my rear wheel building technique.

Once the initial slack is out of the spokes, I concentrate completely on the drive side. I get the wheel round and tension on the drive side almost or to the desired tension.

Then, use the NDS to pull the rim to center and adjust the side to side.

There is almost no increase in DS side tension if you do it this way and it is fall off a rock easy.

cycle_maven

^ this.

Tension the DS, lateral true and dish with the NDS. Try for as even as possible tension on the NDS too, of course.

RandomTroll

I pulled a nipple through an eyelet once. That turned the rim into a Pringle™, a condition that persisted even after I removed the spokes. I relieve tension continuously while building, sometimes solely to keep my hands busy while I think.

RandomTroll

Why? The saving in weight is negligible. A correspondent in another thread mismeasured his rim's ERD (shouldn't be doing any mechanical work, I guess) but was lucky to get the LBS to cut them shorter for cheap - would this work had he bought double-butted?

Dan Burkhart 

Double butted spokes usually afford up to about 20mm for shortening. I cut and re thread them all the time.

Jiggle

Durability.

FBinNY 

For most applications, DB spokes build stronger, more durable wheels than plain gauge spokes of the same nominal size.

Spokes break at elbows, and occasionally at the 1st thread. Thinning the center section reduces deflection in those critical areas, and slows the fatigue process.

RandomTroll

Howso?

I misunderstand. I thought the point of a DB spoke was to make the spoke thicker (=stronger) where the stress was greater, the ends, yielding a spoke as strong but lighter. 'Thinning the center section' would seem to result in a spoke that deflected more in the center, which deflection would have to propagate to a spoke's ends. If butting spreads deflection over a larger section of spoke, making the deflection at the elbow and nipple smaller, I could see how this helps, but I'm not sure it would do more than a plain gauge spoke that deflected less in the center to begin with.

I've broken 1 spoke in the last 10 years (40K miles).

FBinNY 

What follows is a poor analogy, but might help you see the concept, which I'll get back to after.

Imagine tying a boulder to a rope strong enough to support it's weight, then tossing it over a cliff. When it reaches the end of the rope, the rope may snap because, while it's strong enough for the boulder, it's not strong enough to stop the moving load. Now do the same thing, but tie a length of bungee into the system. The stretching bungee increases the the boulder stopping distance, and reduces the dynamic load to within what the rope can hold.

---

Something similar happens with butted spokes. Keep in mind that riding a bike doesn't directly change the spoke tensions much. It changes the spoke LENGTH through rim deflection, and the tension changes are a result, not the cause.

So if a spoke elongates or shortens by a set distance, the tension will change uniformly throughout the spoke (tension has to be uniform along any string). But for the same tension change, the amount of deflection will be proportional to the cross section of each section. By the thinner sections making more of a change, the thicker ones make less (total length change is constant). In essence, the secret to butted spokes is that they move deflection from the ends to the center.

I hope that helps.

noglider 

@lostarchitect, that's pretty good. Where does it come from?

79pmooney

There is a very good reason for lacing a wheel so that the drive side spokes are as yours are and it has nothing to do with the wheel. If this is a derailleur bike, the day will come when you will drop your chain between the spokes and the inside cog. (This is a "when" not an "if". Hasn't happened yet? Keep riding.) When that chain drops in there, you will regret riding a wheel where the spokes at the top of the hub face forward and have the heads out. Those spokes will actively pull the chain in deeper. Damage to your derailleur, possibly dropout, chain and hub will happen. You will not be riding home. Now, if your wheel is what we used to call "inside pulling" (just another way of saying what you have), those spokes will do their best to try to kick the chain out of the gap. If you are standing on the pedals, they will not be able to, but in any case, the damage will be far less and you have a good chance of being able to jury rig a ride home and save the wheel, derailleur, and dropout. If I receive a rear wheel that is not inside pulling, it is a spare only until I rebuild it.

The same principle applies to the rest of your spokes, non-drive side and front wheel, but here it will be branches, string, etc. that will be sucked in or repelled. Machine built wheels are usually built as yours is, so only one side is laced to repel stuff.

I have to thank one-time mechanic Michael Gilday (and probably his friend, Sheldon Brown) for this advice presented to me orally many years ago. It has served me well.

Ben

RandomTroll

The difference between a DB spoke and a SG spoke is that the center of the DB is thinner; the ends have to be the same thickness to fit through the hub and into the nipple. Won't butting just make the center deflect more, the deflection at the ends staying the same? Total length change is a function of the strength of the whole spoke: thinning the center will make it weaker, resulting in more deflection.

I thought that some of the stress on a spoke is shear stress: the propagation of the shear necessary for the wheel to carry me forward, that this shear making the spoke deflect back and forth wore it out at the top of the nipple and in the hub, not tension and compression.

FBinNY 

I thought I explained it fairly well, or as well as I can within the limits of time, space and my patience. There's no place to go from here, so I'm out. If you're happy with the spokes you use, then you don't need my help. If you have a mechanical problem, I'll be happy to help, but pointless debate on engineering isn't of any interest to me.

If you're really interested the rational of DB spokes, there's plenty of literature on the subject.

Reynolds 

Hasn't happened to me in 20+ years and more than 100000 kms. I keep riding, however.

Jiggle

Strength is not stiffness.
Strength is not stiffness.
Strength is not stiffness.
Strength is not stiffness.

And the word you should use is strain, not deflection.

The ultimate tensile strength of a new 1.5mm effective diameter Sapim CX-ray is four times greater than any load it will ever experience. The strength of a 2mm straight gauge spoke is double that. BUT, since the stiff center section of the straight gauge transmits all the stress to the elbow, the elbow of the straight gauge spoke will fatigue and break much more quickly.

Why doesn't the center of the db spoke break instead of the elbow? Steel is a wonderful material because it has a fatigue limit. The fatigue at the elbow goes over that limit much more easily than the center section. This is because stress is greatest at the surfaces of any bending beam, and the elbow is bending while the center of the spoke is only in tension.

So it is the increase in flexibility that improves durability. The loss of strength is present but negligible. In a 32 spoke wheel, using 1.5mm db spokes will decrease stiffness about 10% from 2mm straight spokes.

miamijim

I dont do any of those....

miamijim

+1.

Another good technique is initialy over dish the wheel then bring it back to center with the NDS spokes.

RandomTroll

Sounds like a job for Spoke protector!