Aluminium Nipples - Fragile? Also-why bother?

[WyvernRH]

So, this morning my wife hit a pothole at a reasonable speed on her Focus Paralane gravel bike and we heard the 'Twang' of a spoke breaking (apparently). On inspection, it proved not to be a broken spoke but a failed aluminium nipple. Straight snap failure from a stress point at the internal thread, no pre-failure crack IMHO. Rim was perfectly fine when we did a close inspection back home.



Now the bike has Alex Boondock rims intended for gravel work (see picture), I would not have expected a failure of any sort with this sort of bump.


So, questions for all you weight conscious speedy types out there.
1) Is this a common occurance? Have I reached the fatigue limit for the nipples on this 3 YO wheel so they are going to fail one by one? Am I going to have to rebuild the wheel with sensible brass nipples?
2) WTH use aluminium nipples anyway . The weight saving seems pitiful on a gravel bike and to me at least it looks like a corrosion/adjustment problem waiting to happen on a mass-produced wheel.

Must admit I'm tempted to just spend an hour stripping out and replacing all the alloy nipples just so i don't have to do at a campsite in the middle of the boondocks one day

Richard

[P!N20]

I had to replace all the aluminium nipples on the wheels that came standard with my hard rubbish find Focus Mares CX. Most just crumbled when I tried to turn them.

[queequeg]

It makes bugger all difference to the weight of a single wheel, but the cheaper nipples when scaled out for a wheel manufacturer is a big cost saving.

I hate them with a passion and will always use brass nipples on my own wheels because the aluminium ones become brittle and crumble, and unless you have a three sides spoke key, don't try and turn the nipples or you'll just round them off!

[Duck!]

Aluminium nipples can just get lost (to put it politely), for all the reasons previously mentioned. They corrode, go brittle and disintegrate, leading to less reliable wheels, and the weight saving is basically eff-all, around 50g for a 64-spoke pair of wheels (32 each end), and they're more expensive than brass, for a vastly inferior product. I refuse point blank to build with them.

The breakage shown in the OP indicates that the spokes are too short and are not threading right up into the nipple heads. The inherent absence of fatigue resistance in aluminium means that the unsupported nipple heads will be very happy to pop off; if one has gone the others will follow.

The solution can go in two steps: first, replace all the nipples with brass, they're a lot stronger and will tolerate short spokes much better. Second, in addition to brass nipples, replace spokes with ones 2mm longer so they properly thread into the nipple heads.

[WyvernRH]

Thank you for the replies and advice folk, much appreciated.
Afraid you just confirmed my thoughts on these dodgy items so I will be sending off for a packet of black 14g brass nipples and rebuilding ASAP.
I'll risk the short spokes for the time being. There was actually about 1mm of spoke sticking out of the break so I reckon the brass nipples will cope. We shall see I suppose...

Richard

[baabaa]

Interesting thoughts and I will throw in my 2 cents worth.

Think all my wheelsets have brass nipples but would need to check on the factory made single speed wheels.

The last set of touring wheels I had built up (in Germany) I specs with blue dt nipples, really just to go with a blue hope hub and a blue Shutter Precision dynamo hub.
They - the nipples - are now six years old and look as new when compared to the spare nipples I bought with the wheels. BUT what I do like is that this wheelset has not moved out of true, or made any sounds in any way from riding with loads in snow and salted iced roads to Australian temps of 40 c so the road temps must + + on that.

I kinda think that most brass and aluminum nipple issues come from not using eyeletted rims, the ones I had built are double eyeletted. Guess time will tell but my thoughts are that yes best avoid aluminum but why do they keep making something so bad? The big players like dt and Sapim must know something around this or they would just stop making them.
I asked the builder at the time about the brass vs aluminum nipples and they said they would not build wheels with them if they had or have found any longer term issues.

So I guess my sum up from this is the rims I have with brass but without eyelets are or at least seem more problematic and need to be trimmed while the rims with single and double eyelet just stay true. And, the more you need to play with them, I guess they more they are inclined to be damaged)

In your case, it could be a wear point between nipple and the rim? It now seems pretty hard to by any off the rack bike with eyeletted rims, which to me sounds like a bigger issue to the non enthusiast bike buying public than the type of nipple materials used?
Maybe... and if you do have eyeletted rims I will just hide behind the sofa for a bit.

[warthog1]

One set of wheels there has brass nipples, largely on advice from here. The rest aluminium.
Over 150k km in the last 12ish years on them.
No nipple problems whatsoever.
The only aluminium wheel that gets ridden anymore are the dt swiss gravel goers. I need to chuck some stuff out.

[WyvernRH]

Interesting thoughts and I will throw in my 2 cents worth.
<snip>
In your case, it could be a wear point between nipple and the rim? It now seems pretty hard to by any off the rack bike with eyeletted rims, which to me sounds like a bigger issue to the non enthusiast bike buying public than the type of nipple materials used?
Maybe... and if you do have eyeletted rims I will just hide behind the sofa for a bit.

You may have a point there. The deep rims do not have eyelets and the snap point on the nipple is pretty much on the nipple/rim interface. I swapped out all the nipples for brass ones on the front wheel this arvo and several of the old nipples had distinct wear marks on one side of the rim/nipple interface. Also, corrosion had started on the threads of several nipples and also on the inside of the rim on some. Didn't help that they were as dry as a bone. Swapping out all the nipples on the rear wheel to-morrow.

It is quite a time consuming job due to the deep rims. I've made a special tool (bent spoke) to help remove the old nipple and insert the new nipple so I don't drop a nipple into the rim but is still a multi - action task for each spoke. Unscrew and remove the old nipple -unscrew from tool/Screw new nipple onto tool and insert the new nipple/Get it started on the spoke, remove tool/tension up - all without dropping a nipple into the rim. Sure glad I don't build wheel professionally any more

As an aside, how do you easily tell if you have alloy nipples on a wheel? The magnet test won't work cos if IIRC brass is not magnetic either.

Richard

[find_bruce]

easy to weigh when not fitted, destructive testing is also easy (phosphoric acid)

No idea how to figure it out in situ

[Duck!]

As an aside, how do you easily tell if you have alloy aluminium (brass is also an alloy) nipples on a wheel? The magnet test won't work cos if IIRC brass is not magnetic either.

You can tell by the colour, at least in raw finish. Brass (pretty much always nickel-plated) nipples have a very shiny and feintly yellowish tint, where aluminium nipples will have a duller, more grey tint. Black nipples can be harder to differentiate, but not impossible - scratch through the coating in an unseen section. the underlying metal colour will indicate what it is. Any other external colour will be aluminium.

[find_bruce]

My resident metallurgist says there should be a measurable difference in electrical resistance - aluminium is 2nd only to copper. I don’t have any aluminium nipples to test the theory

[P!N20]

As an aside, how do you easily tell if you have alloy nipples on a wheel? The magnet test won't work cos if IIRC brass is not magnetic either.

Try to turn one, if it crumbles it’s aluminium

[baabaa]

So to arrest misinformation; as the relay of watt is currently positive news, no one should have any resistance to use aluminum nipples to generate electricity and or lighting with a dyno hub wheelset?

[WyvernRH]

As an aside, how do you easily tell if you have alloy aluminium (brass is also an alloy) nipples on a wheel?

Heh, you got me! Third glass of wine mistake - should have been 'alu'.

You can tell by the colour, at least in raw finish. Brass (pretty much always nickel-plated) nipples have a very shiny and feintly yellowish tint, where aluminium nipples will have a duller, more grey tint. Black nipples can be harder to differentiate, but not impossible - scratch through the coating in an unseen section. the underlying metal colour will indicate what it is. Any other external colour will be aluminium.

Sadly all the in-situ ones I want to check are indeed black. I was hoping that someone had a clever method I hadn't thought of but looks like I'll have to get the jewelers files out and scrape the surface off a couple.

Pretty sure the conductivity test won't work on in-situ nipples. If they are loose then weight is indeed the give-away.

Thanks for the assistance folks!

Richard

[blizzard]

I have alloy nipples on my Light Bicycle wheels, so far no issues after almost 4 years and a 14000km.

Is there any advantage dripping some chain lube on the nipples every now and then to prevent seizing / corrosion? I have done it in the past but not in the last 18months or so since I've barely ridden the bike lately

[Mr Purple]

Yep. My Light Bicycle wheels have aluminium nipples and 22,000km with no issues.

However I did go brass in my gravel Farsports. Weight is far less important and they often go underwater.

[headasunder]

some of the dt swiss rim range come with the squorx nipples and washers supplied, the nipples are pro lock and alloy so unless you to buy the squorx brass nipples (which arent cheap) you build with the alloy ones.

[WyvernRH]

So, as a bit of a wind up from my point of view. I have replaced all the aluminium nipples in my wife's Paralane's wheels with brass equivalents. Many of the aluminium nipples removed were showing signs of fretting on one side of the nipple at the spoke/rim interface. Also spoke/nipple corrosion was starting on some spokes...

Checking the nipples on my Felt cross bike and my wife's Focus MTB they seem to be also aluminium. I'm going to wait for the first failure and then swap the lot out on each bike as required.

No concept at all why use of this type of nipple was thought a good idea except some production engineer <sic> type running with cost savings.

Richard

[LG]

My very recent experience with aluminium nipples, broke a spoke on my Oval rear wheel (527 model I think), snapped at the J bend not at the nipple. Thought it would be a simple job of undoing the broken spoke from the nipple, threading a new spoke through the hub then re-tensioning with the nipple. No, the nipple was completely seized on the spoke so ended up needing to pull the tyre off, lift the rim tape and install a new nipple (brass). Then tried to adjust the tension on some other spokes while the wheel was in the truing stand but all the aluminium nipples I touched seemed to be frozen onto the spoke. Not a fan either.

[elantra]

From all of the above I get the impression that for long and faithful service you need a wheel with stainless spokes and brass nipples.

I have some older wheels which now look terrible presumably because they lack corrosion resistance.
But I will continue to use them because they are perfectly true and spin effortlessly.
As you would expect they were picked up for not much money and not recently.

One is a Campagnolo Omega 32 spoke wheel which rides beautifully when used with an early 1990’s Technotrat frame.
When I first got it (at a garage sale) I thought it was only fit for tossing as the aluminium nipples are almost unrecognisable with fungating corrosion.

Then there is a Velocity wheel which someone built up with a type of spoke that looks very sh..T because of a fine grey and brown rust.
Works just fine though.

And an Aksium wheel that has black coloured bladed spokes sporting a subtle sprinkler of rust spots.

I suspect the truth is that spoked wheels are surprisingly complex with lots of pros and cons to their component choices, nipple material/ spoke materials/ eyelets etc
I also suspect that it depends on usage factors like exposure to fresh water, salt water, even sweat etc.

[baabaa]

I suspect the truth is that spoked wheels are surprisingly complex with lots of pros and cons to their component choices, nipple material/ spoke materials/ eyelets etc
I also suspect that it depends on usage factors like exposure to fresh water, salt water, even sweat etc.

This is a good call. I now see that Phil Wood only make and sell brass nipples (but in black and silver). They also make spoke cutting machines which I believe are quiet well considered in and around the wheel building sector.
Have also been thinking a bit around this and with nothing other than a hunch maybe add in that if possible best try and buy the same brand / manufacturer of nipples and spokes, could be something in the in-house milling of threads?

[CmdrBiggles]

I'll sit silently in the shadows waiting for somebody to tell me that carbon fibre nipples exist...
I'm sure weight-weanies will stop at absolutely nothing...

[redsonic]

I'll sit silently in the shadows waiting for somebody to tell me that carbon fibre nipples exist...
I'm sure weight-weanies will stop at absolutely nothing...

They need to invent "press fit" spokes, so they can do away with the annoying need to introduce a thread to a carbon fibre component...

[blizzard]

Lightweight already does fully bonded carbon spokes without nipples. If you break the wheel you have to send it back to them for repair.

[redsonic]

Lightweight already does fully bonded carbon spokes without nipples. If you break the wheel you have to send it back to them for repair.

What a great idea. NOT.