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Discussion Starter · #1 ·
So, here's the story... My first carbon wheel project

Rims: NEXTIE NXT29AM35, 32h
Hubs: DT Swiss 240 15qr fr, 12/142 r
Spokes: Spaim Laser, 3x
Nipples 14mm brass, no washers on the advice of NEXTIE
lube: boiled linseed oil

Prep:
1)I measured ERD extremely carefully, correcting for nipple size, etc
2) did measure some non-uniformity in the ERD of the rim (probably) due to slight variation in spoke bed thickness. But less than 0.5mm

Problems:

1) drive side nipples seize at about 100-110kgf tension
2) 1 spoke location nipple fractured due to seizing and over torquing, but at pretty low tension
3) carefully had to replace that spoke, but it was not pretty. re-laced the spoke and slowly retensioned wheel and re-true, vertically and laterally
4) several nipples seemed to seize at around 100-110kgf, so I stopped. I think a few others may have small cracks

Rim say it can go to 150kgf, hube is like 125kgf. So.. not at the limits at all.

Needless to say, this stresses me out. Here's my hypothesis explaining what is happening:
1) friction between nipple and carbon rims is MUCH higher than aluminum
2) linseed oil doesn't lubricate enough
3) nipples are bad (like bad batch???)
4) ERD calculation is off... but spoke head is exactly where you'd want it to be with respect to the nipple when tensioned.
5) the spot of the fractured nipple has a different ERD that the rest of the rim.
6) should have used washers

I fully expect the have to completely rebuild the wheel and am really upset since I've successfully built great wheels in the past.

Kinda stymied by this problem.

Any thoughts?
 

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I should be out riding
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Personally I found the difference with and without nipple washers to be striking. I'll be sticking with them in the future. IIRC Ibis was recommending them.
 

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Hitching a ride
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I'm interested in the mode of fracture. Are you sure you aren't bottoming out the nipple into the unthreaded part of the spoke? That would stress it a lot, splitting it.
 

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damned rocks...
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I didn't find particularly difficult to lace my carbon rims, I just lubed the spokes, the nipples and the interface with the rims with thin oil.
No problem at all.

The weird part is the nipple cracking, picture would be nice.
First guess would be bottoming out, but you said to have accounted for the extra thread length of the 14mm nipples.
 

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Discussion Starter · #7 ·
I'm with the nipple bottoming-out camp. What brand are the nipples? The thread engagement for a given nipple length will vary between models. There's an easy way to tell if you've got a spare spoke and nipple - just thread them together all the way and see where the spoke end is. If there's no spare spoke and nipple then undo one nipple on the wheel, pop the spoke out of the rim and then thread the nipple all the way down.
If the nipples are bottoming out then all is not lost: there should be nipples out there with a more favourable thread engagement, and Sapim HM nipple washers bring the nipple up by about 0.7 mm (increasing the ERD by 1.4 mm). These washers certainly make the final tensioning easier, but (as I found out the hard way) the nipples will rattle loose with tensions under about 100 kg.f, at least when the nipple seat is greased; linseed might work better.

If there's no bottoming out then maybe check the seated nipple angle matches the spoke angle. This could happen with rims with angled holes where the spokes are all off by one hole.
This is an excellent suggestion! I have extra spokes and am going to verify via caliper measurements if the the spokes are bottoming out. I think the nipples are regular sapim brass 14mm, but will check.

Maybe I need to rebuild the wheel with the same spokes, new nipples and washers if I have the thread length to do that.

Sent from my SAMSUNG-SM-G900A using Tapatalk
 

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You might also verify that your spokes were actually cut to the right length. What sort of tones are you getting when you pluck the high-tension spokes near the nipple?

I assembled a set of very similar carbon rims with 32H Laser 3X, Sapim 12mm alloy nipples, and Sapim washers. Used a Slick Honey analog on the spoke threads, a bit of Tri-Flow on the nipples, and a conventional Park spoke key. They weren't hard to tension. The worst damage to any nipple was rubbing off a bit of anodizing.

I've seen a few reports of raised nipple holes on carbon rims. That was reason enough for me to use nipple washers. I'm taking Jobst's word, however, that this configuration won't unwind on the trail.
 

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I have a feeling that we would see spoke coming through the base of the nipples if we could see them. I recall that the source I got lasers from only offers 2mm increments. I always choose the lower of two close options. If you went with the longer option that would lead to the problem you're having. The 14mm nipples may be adding to the issue. I would switch to 12 AND use the washers.

Also make sure you're marking those spokes when tensioning so you see windup. They will twist quite a bit if you're not careful.
 

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damned rocks...
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This is an excellent suggestion! I have extra spokes and am going to verify via caliper measurements if the the spokes are bottoming out. I think the nipples are regular sapim brass 14mm, but will check.
(...)
Sapim nipples don't have extra thread.
They have the exact same tread as s 12mm niple.
The only nipples that I know to change thread size are the ones from Dt.
 

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1)I measured ERD extremely carefully, correcting for nipple size, etc
Sapim 14mm nipples do not need correcting.

1 spoke location nipple fractured due to seizing and over torquing, but at pretty low tension
Where did the nipple fail?

Just to add... Spokes do not bottom out in nipples. You can easily screw a nipple right down and beyond, all that happens is that the nipple threads become deformed. There will be a slight increase in tensioning torque, but nowhere near enough to cause the nipple to fail.
 

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Just adding my 2 cents. I find carbon wheels to be considerably easier to build up than alloy simply because theyre so stiff. The tension builds up very quickly and evenly.

Like some of the others mentioned, Are you sure that youre not running out of threads, and the spoke isn't poking way out the back of the nipple? Or maybe the spokes were cut incorrectly and the threaded length is a bit short? From the way you describe your nipples, maybe you got counterfeits? I've used a ton of sapim nips and never had a stitch of trouble from any of them.

One other thing is to really watch out for spoke windup with those lasers. I'm sure that's not whats giving you the trouble here, but its worth keeping in mind.
 

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Discussion Starter · #13 ·
Sapim 14mm nipples do not need correcting.
I mean that I corrected for the change in ERD due to how the nipple sits so that the spoke would end up "not too far in" or "not too far out".

I do not have a picture of the spoke treads showing the where the end is, but it is nearly flush with the top of the nipple.

I also verified how far this specific spoke/nipple combo will go before bottoming out - it's like 1.5mm beyond where they are now. I will take a picture soon as I have to replace the valve stem with a longer one.

I'm really wondering if the tension meter I used is off - it's a friend's that runs a semi-professional bike service business out of his garage, so I assumed it is good.

A few positive notes:
1) the wheel wasn't that difficult to build, except for the few spokes that bound up
2) the wheel rides very nicely.

The front is laced and I may tension and true it tonight. I used A LOT more lube on this one and am gonna go even slower.
 

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Check the tension meter on another wheel that you know is built well. Should be enough to tell you if its WAY off.

Thats good that the spoke can go another 1.5mm further out the back than where they are now. But youre checking that visually from the back of the nipple, not measuring a tensioned spoke vs an untensioned spoke, right?

I think what he means is there's no need to adjust ERD for a 12 vs 14mm sapim nipple. The threaded portion of the nipple is the same, only the unthreaded "sleeve" portion is longer. Ideally you still want the spoke to run just about flush with the back of the nipple.
 

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Discussion Starter · #15 ·
Just adding my 2 cents. I find carbon wheels to be considerably easier to build up than alloy simply because theyre so stiff. The tension builds up very quickly and evenly.

Like some of the others mentioned, Are you sure that youre not running out of threads, and the spoke isn't poking way out the back of the nipple? Or maybe the spokes were cut incorrectly and the threaded length is a bit short? From the way you describe your nipples, maybe you got counterfeits? I've used a ton of sapim nips and never had a stitch of trouble from any of them.

One other thing is to really watch out for spoke windup with those lasers. I'm sure that's not whats giving you the trouble here, but its worth keeping in mind.
Spokes and nipples where ordered from Dan's Comp.... used them before without issue, but I will confirm that I got the right stuff.

How does one verify a nipple?

I did not verify spoke length prior to building, but everything was labeled, etc.

Trust but verify, I suppose.
 

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Hitching a ride
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Above 100 kgf, my Park reads higher than the real tension. I'm actually around 145 on the chart for 130kgf actual, verified with my tension meter calibrator.
 

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A laser is a 1.5 spoke, so your tension at 20 is 130kgf. That's a crapload of tension! Boiled linseed isn't known for doing a great job of reducing friction.

If your gauge is miscalibrated by one, you could be cranking somewhere around 150kgf.
 
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