Classic & Vintage - The woes of aluminum spoke nipples

I have a beautiful semi-classic wheelset, Campy cassette hubs, Mavic rims, butted spokes, the stuff that begs to be seen and ridden. It is in perfect shape, with obviously very few miles ridden before I got a hold of it a few years ago. True and round.

Now, the wheelbuilder who was commissioned to do the job back in the day must have glanced at the bike it was destined to go on because he indulged in blue nipples, matched perfectly to the primary frame color.

Unfortunately colored nipples are predominantly aluminum.

One day last week I lifted the bike out of the car and sat it down a little hard. Ping! Sheared nipple. Put it on the stand, fixed it and for fun grabbed several sets of parallel spokes to test the tension. Ping! Ping! Ping! All sheared right at the shoulder where the nipple seats. No oxidation or other decay. Simply stressed from being tensioned for a handful of years. No way I was going to ride that, so on to a complete rebuild with dull, non-exciting brass:)

Off course this is not anything new. I have handled enough wheels to know that in one frustrating way or another alloy nipples are just not worth my time.

I will admit one, and just one, totally babied, barely ridden, race-day only aluminum nippled wheelset in the house, but it must be exceptional in every conceivable form and fashion to stay!

Wowza. I generally agree with you, though never had any sort of experience like that to back it up. Decided to go with the brass nipples on the wheel build for the Kirk, extra glad I did now.

I am far too much a traditionalist to attempt anything but brass nipples. Besides, it is far too risky to use aluminum for a high stress portion of the bicycle like a spoke nipple atmo.

My winter ride originally came with alloy nipples and you can guess the rest.
It is incomprehensible to me why they continue to make them.

My winter ride originally came with alloy nipples and you can guess the rest.
It is incomprehensible to me why they continue to make them.

They're for the weight weenies who only ride them for races and usually toss the whole kit afterward.:rolleyes:

Hmm, I have a lightweight wheelset with XTR hubs and nice blue alloy nipples for my son's mtb for this season. Maybe I should swap them out for brass now before they all strip out, since I'm in wheelbuilding mode anyway.

... Ping! Ping! Ping! All sheared right at the shoulder where the nipple seats. No oxidation or other decay....

Off course this is not anything new. I have handled enough wheels to know that in one frustrating way or another alloy nipples are just not worth my time. ...



Thanks for that. I've never used aluminum nipples and your post gives me another reason not to.
But is it possible that the spokes were a couple of millimetres too short so that the shoulder of the nipples was not being buttressed by the spoke? In the one (brass) nipple I've ever seen break at the shoulder, the spoke ends didn't come right to the screwdriver slot. I'm just wondering if this could be an additional cause of wholesale failure of aluminum nipples.

Thanks for that. I've never used aluminum nipples and your post gives me another reason not to.
But is it possible that the spokes were a couple of millimetres too short so that the shoulder of the nipples was not being buttressed by the spoke? In the one (brass) nipple I've ever seen break at the shoulder, the spoke ends didn't come right to the screwdriver slot. I'm just wondering if this could be an additional cause of wholesale failure of aluminum nipples.

This was not that case with my Marin (winter bike).
If it were, then I'd have to imagine all 72 of them would have unzipped on day one!

Ouch!

I never concern myself with wheel weight - I might drastically reduce the weight of most other components, but a sturdy, well-built wheelset under every bike I own (not to mention my highly-valuable self :) ) is an absolute must!

DD

Hmm, I must be lucky. All my bmx wheels had aluminum nipples, as well as a couple sets of mtb wheels. I wore through the rims on the mtb, but never broke a spoke or nipple.

I have one wheelset with aluminum nipples. I bought it from a retired racer that used it in the eighties. The hubs are Campy Record and the spokes are eliptical. Even though I re-spaced and re-centered the rear and then converted it back for gears and have recently replaced the rims, the original nipples haven't been a problem. The wheels are currently on a Peugeot that I set up for riding on dirt roads with cyclocross tubulars. I use a good spoke wrench and I make it's fully seated on the nipple.

My winter bike often sees hard use over heavily rutted roads, and gets used 10 or 20 times as often as any other single bike I own. Fatigue failures hinge on the level of stress and number of life-cycles, so YMMV, depending on your weight, riding habits, etc.

I had a set of wheels built (by me, before I knew better) with alloy nipples. The nipple shoulders work-hardened and cracked over time, and would shear off. Never again.

The issue is probably fatigue. Just as improperly tensioned spokes will fail in fatigue, over time; aluminum nipples with improperly tensioned spokes will fail much more quickly. Another possibility is a subtle corrosion issue, not evident on cursory visual inspection.

I build wheels and warranty them for the life of the rim... unless they have aluminium nipples.

Have built some wheels with aluminium nipples and the racing wheels on my XC bike were built with black anodized nipples and have been holding up for many seasons... but as these are my wheels I check them regularly to make sure things are as they should be and they are still 5 by 5.

I cannot control what happens to wheels when they leave my little shop and most people seem to understand that the weight saving you get from aluminium nipples is not worth the increased potential for failure and decreased servicability... I have handled a lot of nipples in my life :) and brass nipples take a better thread that is less likely to strip or deform under repeated stress cycles.

When you are looking at servicing a wheel 10,000 km down the road it is nice to deal with nipples that, even if they have a little corrosion can be turned while seized aluminium nipples will round off all too easily.

Alloy nipples aren't bad if you plan on wearing out the rims in a couple of years. They only get bad for you classic guys that don't ride your bikes enough. :lol:

Saw a cyclic fatigue chart for an aluminum alloy showing sample parts statically stressed to a safety factor of 4 with a relatively small cyclic loading applied live for about 10,000,000 cycles. If the nipple were in such a loaded condition and cycled once per loaded rotation of the wheel, it would theoretically reach its service life in 10 million rotations of the wheel. If the wheel were running a 700 x 25c tire, and had a 2105mm circumference, or 82.9 inches, or 6.91 feet, it would rotate 764.5 times per mile and would live to 13,080 miles at 10 million cycles when half the nipples would likely statistically fracture.

That doesn't explain the fracturing of them on lightly used wheels, where I'm more likely to think galvanic corrosion from contact with the steel spokes, overloading with an overweight rider during it's short service life, or simply defective nipples that came from the manufacturer with inclusions, voids, microcracking etc.

I have a beautiful semi-classic wheelset, Campy cassette hubs, Mavic rims, butted spokes, the stuff that begs to be seen and ridden. It is in perfect shape, with obviously very few miles ridden before I got a hold of it a few years ago. True and round.

Now, the wheelbuilder who was commissioned to do the job back in the day must have glanced at the bike it was destined to go on because he indulged in blue nipples, matched perfectly to the primary frame color.

Unfortunately colored nipples are predominantly aluminum.

One day last week I lifted the bike out of the car and sat it down a little hard. Ping! Sheared nipple. Put it on the stand, fixed it and for fun grabbed several sets of parallel spokes to test the tension. Ping! Ping! Ping! All sheared right at the shoulder where the nipple seats. No oxidation or other decay. Simply stressed from being tensioned for a handful of years. No way I was going to ride that, so on to a complete rebuild with dull, non-exciting brass:)

Off course this is not anything new. I have handled enough wheels to know that in one frustrating way or another alloy nipples are just not worth my time.

I will admit one, and just one, totally babied, barely ridden, race-day only aluminum nippled wheelset in the house, but it must be exceptional in every conceivable form and fashion to stay!

You really should take a peek to see if the ends of the spokes have made it at least to the screwdriver flats of the nipples...

=8-)

Alloy nipples aren't bad if you plan on wearing out the rims in a couple of years. They only get bad for you classic guys that don't ride your bikes enough. :lol:

I ride my bikes enough... :)

Alloy nipples aren't bad if you plan on wearing out the rims in a couple of years. They only get bad for you classic guys that don't ride your bikes enough. :lol:

I don't know how people wear out rims in a couple years. I have rims with over 20,000 miles that look new. I use Kool Stop pads, and clean them up and remove embedded metal bits after a long ride in the rain. I could see wearing them out if I did a lot of rainy rides in the mountains, but I make do with just commuting when it rains.

I don't know how people wear out rims in a couple years. I have rims with over 20,000 miles that look new. I use Kool Stop pads, and clean them up and remove embedded metal bits after a long ride in the rain. I could see wearing them out if I did a lot of rainy rides in the mountains, but I make do with just commuting when it rains.
That one is easy, mtb in the mud and rain with rim brakes. A heavy rider could wear out a set of rims in a season or two that way.

Saw a cyclic fatigue chart for an aluminum alloy showing sample parts statically stressed to a safety factor of 4 with a relatively small cyclic loading applied live for about 10,000,000 cycles. If the nipple were in such a loaded condition and cycled once per loaded rotation of the wheel, it would theoretically reach its service life in 10 million rotations of the wheel. If the wheel were running a 700 x 25c tire, and had a 2105mm circumference, or 82.9 inches, or 6.91 feet, it would rotate 764.5 times per mile and would live to 13,080 miles at 10 million cycles when half the nipples would likely statistically fracture.

That applies for the assumed pre-tension and cyclic loading. Improper tension will throw those assumptions out the window and drastically shorten the fatigue life.

... so on to a complete rebuild with dull, non-exciting brass:) ...



Besides, who says brass is dull and non-exciting? We have a little brass bell from Velo Orange mounted on our tandem. I polish it up every time we're going to be riding with other people and it is the brightest star in the firmament. Thrilling! Talk about bling! I can hardly contain myself from the excitement of it all! (Little kids love it. We ding it for them when they say, "Look, Dad! That bike has four water bottles!!!")

Oh yeah, the nipples are brass, too. All 76 of 'em.

Thanks for confirming what I suspected. I've only built a couple wheelsets so far, but I've used brass nipples because I feared this kind of issue. I will continue to do so.

Can only imagine if they had all decided to go during a quick descent. Scary thought.

I never thought alu nipples were a good idea, and I've seen enough evidence to confirm that. I know some people say there's nothing wrong with them, and that's fine for them, but not for me.

Just wondering, would Ti be a viable material for spoke nipples??
On my last wheelbuild, I didn't take the aluminum nipples that came with the DT Aerolite oval spokes that my LBS ordered for me and I asked for brass nipples for the spokes instead. I was surprised that the older LBS owner seemed puzzled by my decision. It seems like maybe the verdict about aluminum spoke nipples is not yet universal out there with even people that we might think would very knowledgable about it. Only expalnation I might have with the LBS's owner's reaction was maybe he didn't really want the trouble of trying to sell the aluminum nipples??

Chombi

I can't seem to get more than 20 years out of a wheelset built with aluminum nipples.

Conversely, I've built high tension wheels with aluminum nipples, and have not had any problems. Not that it was my first choice... it was just what my shop had on hand at the time.

Conversely, I've built high tension wheels with aluminum nipples, and have not had any problems. Not that it was my first choice... it was just what my shop had on hand at the time.

Do you use grease or anti-seize on the threads and where the nipple's flanges meet the eyelets?

Also, won't a higher spoke count add longetivety with proportionally less static tension and less cyclic tension on each spoke (while simulateously defeating the weight weenie advantage of aluminum nipples)?

I've got a wheelset (Mavic 231 rims laced to XTR M-900 hubs) with aluminum nipples. I wouldn't have built them that way, but that's how they came. Been fine so far. You guys are making me nervous, though.

I can't seem to get more than 20 years out of a wheelset built with aluminum nipples.

You must not ride those wheels very much.

Time is not a usable measure... a poorly built wheel can fail the first time it is taken out or may fail after very low mileage but if you build it and set it on a shelf you are not going to be subjecting it to cyclic loads.

Same applies to a well made wheel... a properly built wheel will run true until it is time to replace the rims due to brake wear and with disc and hub brakes the operational life can be increased further.

Other factors come into play... if your bike only ridden on warm Sunday afternoons it will be less prone to corrosion than a bicycle that sees hard daily use in every kind of weather.

Do you use grease or anti-seize on the threads and where the nipple's flanges meet the eyelets?

Also, won't a higher spoke count add longetivety with proportionally less static tension and less cyclic tension on each spoke (while simulateously defeating the weight weenie advantage of aluminum nipples)?

Yes.

Any advantage to shooting on some PB Blaster or other penetrating oil before doing any truing?

Sixty fiver- I don't know how many miles I have on them but it's many thousand. They are my daily training wheels, 32 spoke, built by me. Over the decades I've had 1000 mile years, 6000 mile years and everything in between. The roads down here are far better than roads up north but I certainly don't baby the wheels. The aluminum nipples are holding up fine.