MarkSch

First whell build.

Tried a number of spoke calculators, sought advice, rounded down, picked spoke lengths.

Finished building rear, trued, dished, and tensioned, but find I have about 2 or so turns of threads per each spoke that remains outside of the nipples....is this a problem? Same on drive and non-drive side.

What might happen?

Should I resize...move the NDS to DS and get new spokes for NDS? Longer nipples? What would be the benefit of either?

Thanks

dabac

This is a heated subject. General engineering guidelines states that once you've got 3 full turns of engagement(or thereabouts) any further turns won't make the interface any stronger. But that is assuming the same material in both male/female parts. Based on that maybe spokes/nipples need a few more.
Someone here believes that all the strength of a nipple is located in the flange of the nipple, and that unless you have spoke penetration through the nipple flange the strength of the assembly is compromised.
I don't believe that, neither from an engineering standpoint nor from an experience perspective. I've got plenty of miles on wheels with supposedly insufficient spoke penetration and they have held up just fine.
One of these days I'll do some destructive testing on threads of engagement vs ultimate strength, but I haven't gotten around to it yet.

If you've got too few turns of engagement there is a definite possibility of pulling the spokes out of the nipple.
My personal guess is that if you've got something like 8 turns in the wheel will hold up just fine.
My personal recommendation would be to switch to longer nipples. It'll look better and might save you from snide comments about poorly built wheels.

MarkSch

Thanks for the response....laced the wheel with 4 full turns to begin with, and have added 3 to 4 more in tensioning / truing / dishing.

Maybe I'll try it like this, and consider longer nipples as the next step, or if I get too many comments.

Al1943

How much tension do you have on the driveside, and what kind of rims and spokes?

davidad

If anyone says anything about it tell em to stuff it and rebuild it for you.
You don't have to do anything to rectify it unless you can't stand the sight of it. I have done it a couple of times and haven't had a problem with either spokes or nipples breaking. I do use brass nipples.
I hope you used a tensiometer to set the tension on the spokes. I like at least 100 to 110 kg.

sfclearwater

I had the same thing happen when I started building wheels. I used a few spoke calculators, rounded down, ended up with spokes that were a bit too short. I switched the (generally standard) 12mm nipples for 14mm nipples because I couldn't stand the couple of threads showing. It is a pretty easy change too, just loosen all the spokes and switch one by one. No need to re-lace.

Some people say that 12mm, 14mm, and 16mm nipples don't (shouldn't) affect the spoke length. In my experience this is not true, in fact some spoke calculators accept the nipple length as criteria and output slightly smaller spokes when a longer nipple is input.

dabac

In that case they don't know what they're talking about, or have used nipples manufactured to another standard than DTs. For DTs it's absolutely clear that a 2 mm longer nipple will cause the threads to start 2 mm closer to the hub.

sfclearwater

Agreed.

Svr

If the spokes don't protrude up to or through the flanges of the nipples, you risk having the nipples fatigue and break at that point. It's more likely with aluminum nipples, but I've seen it happen with brass under heavy and/or powerful riders.

AEO

longer nipples, easiest and cheapest solution

aside from going one cross less, which allows shorter spokes to be used, but this is around the 5~8mm shorter range.

zephyr

Since we are talking here about spoke lengths, what is your favorite spoke calculator? I've used the United Bicycle Institute web calculator, and usually round down to the nearest mm. If I am careful and get accurate measurements for all of the required input info, it works good and is a simple one to use. Once I find a hub and rim combination I like, I stick with it. I also use a sharpie and write the spoke length(s) and date of wheel build on the rim tape.

Anyone noticed that it's not that easy find a place to buy spokes these days? Most LBS in my area (several dozen LBS) carry shamefully few spokes. And then they sell them for at least $1 per spoke. Most times I give up and buy from Cambria Bike website. Any other good places for good spoke selection at a good price?

prathmann

So you have 7 - 8 full turns of thread engagement. That should be plenty, so I'd ride it the way it is now unless the aesthetics of it bother you - they wouldn't bother me.

AEO

spocalc or spocalc express.
then subtract, -1mm for 2.0/1.5mm DB, -1mm for 14mm nipples and -2mm for 16mm nipples.

mrrabbit 

Check the nipple head side of things.

If you can see that the end of the spokes are within a millimeter of the screwdriver flats of the nipples - then that's a pretty good indication that the spoke has penetrated the thickness of the rim seat.

...i.e., no need to worry.

But if that is not the case - then eventually given time and depending upon the quality of the nipple - long or short - nipple barrels will start to crack and separate from the head of the nipples. Head gets lefts on rim seat - barrel slides up and down the spoke like a cheap wheel decoration.

Switching from short to long nipples does not solve the problem...

Sad thing that I am seeing a lot of nowadays is colorful mass produced single-speed/fixie wheels using long nipples to hide 10mm threaded spokes that are purposely cut to just the edge of the rim eyelet. This is done to both reduce scratching of the colored rims during assembly while also avoiding running out of threads in the nipple. (Properly sized spokes will be 2-3mm longer and increases the risk of rim scratching by an assembler in the factory who is working quickly...)

I'm seeing two failures as a result:

1. Barrel snaps...head resides in rim...barrel on spoke.
2. One or more spokes loosen enough such that the nipples pop loose - and somehow flip sideways and get lost inside the rim in the vicinity of the hole that it resided in.


So far the fixes are simple:

1. Relace with spokes that are 2-3mm longer with 10 or 12mm nipples.
2. Relace with spokes that are 2-3mm longer and threaded in spoke machine with 12mm threads for use with 16mm nipples. A lot of folks seem to want those long nipples - especially in black brass and colored alloy.


Night!

MarkSch

Thanks for the interesting and contrasting comments...

This is on a Kinlin XR-300 rim and Formula hub, built 2x...I'll pull the rim strip and check how far up the nipple the spokes come....I'm suspicious they are not quite to the screwdriver flats....On the front that I built up last night, the spokes protrude slightly, and I'm not yet fully tensioned there. Might be able to trade some of the fronts for the DS on the rear.


I am using a tensiometer....pretty high on the drive side...average of 130...but substantially lower on the NDS....70 or so....any higher and the dishing goes off.

Soil_Sampler

fyi-

some 14mm nipples have the same amount of threads as most 12mm nipples.
Sapim 14mm black brass nipples are one.

dabac

Er, what?
The only part of the nipple that would be free to slide on the spoke is the unthreaded part closest to the hub (the first 4 mm or so), and as it's unthreaded it can't carry a load. And if it can't carry a load it can't fatigue.

I've had the occasional nipple snap, but usually in connection with a crash. And on those occasions the "barrel" of the nipple has always remain firmly threaded onto the spoke end.

mrrabbit 

Er, what?

The only part of the nipple that would be free to slide on the spoke is the unthreaded part closest to the hub ( the first 4 mm or so), and as it's unthreaded it can't carry a load. And if it can't carry a load it can't fatigue.

I've had the occasional nipple snap, but usually in connection wiith a crash. And on those occasions the "barrel" of the nipple has always remain firmly threaded onto the spoke end.


Comment:

Just thought I type exactly what you said just to confirm that you basically said what I said while questioning what I said. Kinda weird...had your coffee this morning yet?

Typically in a short spoke situation when the nipple snaps the barrel having a thread or two still in it will have to turn a few times while it is free before is starts sliding up and down the spoke. Eventually it will happen - as many customers wait a day or so riding it before bringing it in - unless of course a thread "glue" or "loctite" was in use.

Bottom line is that if the spoke does not protrude 2-3mm into the rim itself upon build completion - then the "fastener combo" of rim seat, nipple head and spoke end is not really complete or ideal. Instead the load is placed more on the point where the nipple exits the rim - right where the spoke has ended..instead of higher up in the rim where the head of the nipple resides.

I've been building and re-building wheels since 1984 - 2000+ wheels. And I've seen quite a few short spoke - snapped nipple cases since that time - mostly steel wheels with cheap long nipples. (Your typically $30.00 steel replacement wheel variety.)

=8-)

mrrabbit 

Do the visual check.

If you can tell easily that the ends of the spokes are within 1-2mm of the screwdriver flat - then you are okay. 2mm is pushing it - but it's your call.

However, if it feels like you are staring down into a "black hole", i.e., the end of the spoke is 3mm or 4mm down - or by guestimation hasn't even made it into the curve that transitions to the nipple head - consider spokes that are 2mm longer.

Hope I have been of some help...don't mean to take the fun out of things...

=8-)

dabac

So you're saying that a piece of nipple, with (a few) threads still in it, can slip down a spoke? How can it do that, when an undamaged nipple will simply bottom out when it reaches the end of the threads?

Can't see that it matters in this case if its only two turns of thread or the full (abt) 18 turns of thread, too narrow is too narrow.

Or are you talking about something completely different?

dabac

Then you can't be building with stock DT nipples and spokes anyhow. For DT a 12 mm nipple will bottom out at about slightly more than 1 mm protrusion. Trying for more will simply squash the first turns of thread and generally turn the build into a mess and a headache. With stock DT stuff I can't see how your guidelines would be doable.

Al1943

With good spokes and rims you could take the tension on both sides a little higher and still keep the rim centered.
Check the tension with the tires and tubes fully inflated. You may find that you need to increase the tension. The air pressure may also effect the lateral true and dish.

mrrabbit 

Hey dabac...

We are talking about a damaged, and snapped spoke nipple here...

Also...do you even understand what I am saying?

Spend lots of time in a bike shop...do hundreds of wheel builds and rebuilds as I have done - cycle through lots of failed wheels...eventually you will see with your own eyes what I have described...some with threads (damaged) still in them, some without - a nipple barrel sliding up and down the spoke. The cheaper the nipple...the more likely as well...since el cheapo nipples tend to have a thread or two less than quality nipples with more poke through allowance.

It's as though you are saying what I already know - and yet arguing with me...are you even reading my posts and comprehending or are you just a troll?

=8-)

vredstein

The weakest part of any nipple will be any nipple threads that aren't engaged with the spoke threads. There, you'll have a hollow core. To prevent this, you need the spoke threads reaching at least the bottom of the nipple slot.
Take a straw, plug one end, fill it halfway with water, and freeze it standing upright, plug-side down. Then bend the straw. I'm willing to bet it will crease above the ice line, while the ice-filled section remains in tact.

miamijim

I looked inot this awhile ago with standard DT spokes and found there's 2mm of leeway in both directions in relation to a spoke/nipple being threaded to the ideal location.

With 2mm spokes all you need is 6mm of engagement for maximum thread interface retention.