achoo

I just suffered my third sheared-off spoke nipple on my rear wheel today. I was just starting up a short climb, putting steady pressure on the pedals, when I heard the dreaded "TWANG!" from my rear wheel.

I stopped to assess the damage, and it was a drive-side spoke that had the nipple shear right at the base. Not having a cassette tool nor chain whip nor 1" wrench in my saddle bag, I was unable to get the spoke off the wheel and pretty much forced to give up on my planned ride and limp home. Lesson learned: carry spare nipples.

The wheel is a Neuvation M28 Aero 3 with a few thousand miles on it, and in the past couple of months I've been really mean to it - I've gotten about 5 or 6 pinch flats by hitting a nasty bump that's at the top of a short climb near the end of most of my rides that I've really been working hard to get over as fast as I can. I get to the top, I'm gassed and not paying attention well enough, I forget about the bump, and BANG. FWIW, I'm about 210-215, and normally run 23s at about 120 PSI, and this bump is a hard edge of concrete that might even have a steel edge. I haven't hit it hard enough to dent or bend the rim at all, but like I said, I've hit it hard enough to pinch-flat on the bump quite a few times in the past months.

Is the wheel dead? Or can/should I just replace all the nipples, and retension and retrue the wheel? None of the spokes have ever failed, and the rim looks fine.

mtbikerinpa

Sounds like the spoke nipples have been fatigued/stressed. I would replace them and move on

FBinNY 

I say this so often, I can't stand hearing myself say it. Nipples shear off for one reason and one reason only. The spokes are too short.

Warning, angry tirade coming. Skip to the conclusion if you wish.

Think of a spoke & nipple as a screw and nut. Standard fastener engineering calls for the nut to be of a thickness equal to the diameter of the mating screw. so a nipple would have to be 2mm tall. If you look at it you say no problem it's much taller than that, but there's a hitch. The tubular section of the nipple that goes through the rim doesn't have the tensile strength of the spoke, and so doesn't really count. For spokes and nipples to have their full design strength the spoke must go 2mm into the head of the nipple, or about to the bottom of the screw slot.

When the spokes end short of the head of the nipple the nipple itself becomes the weakest part of the system and will fatigue and fail. This shouldn't surprise anybody, but large numbers of expensive wheels are built exactly that way, because it's easier than precisely calculating spoke length and nobody wants to deal with spokes going above the top of the nipple.

The irony in all this is that these days many rims are hollow section so a spoke being a bit long is immaterial.

Now that I've vented, I suggest you seek out a local builder of good repute, and have a decent pair of 32h wheels laced up, using 14g double butted spokes, or given your weight consider 13/14g single butted spokes, at least for the right rear flange. If you don't have a local you trust, PM me and I'll recommend a few you can pick from.

Shimagnolo

Interesting.
I had never thought of this, but it makes sense.

achoo

Makes sense, but...

After the nipple sheared off, I removed its remains and I had to loosen the two adjacent non-drive-side spokes so that the wheel wouldn't rub against the left chainstay. Even after loosening those two spokes, the nipple-less end of the spoke still reached far enough into its spoke hole that it wasn't going to flop around easily. Yet I could easily FEEL the out-of-roundness of the wheel as I limped home. Losing the nipple on one spoke and having the two adjacent spokes loosened therefore had to allow the rim to relax outward a good distance as I could feel it, yet the spoke still reached into the hole where the nipple had been. It pretty much had to extend at least your 2mm into the head of the nipple, and could very well have been past the bottom of the screw slot.

I think I put the sheared-off nipple in my saddle bag. I should dig it out and see if it's brass or alloy.

FWIW, I already have a set of battleship wheels, pretty much just like you describe, except the rear is 36h. I got 'em when I was more like 250 pounds instead of today's 210ish. I don't like 'em as they're too heavy.

cyclist2000

does this apply to all nipples or specific to brass or alloy?, I had one alloy nipple break off at the at the base of the nipple and I thought that the spoke went all the way to the base. I was thinking that the alloy was weaker than brass.

DannoXYZ 

Yes, but it's only a difference in amount of time it takes to snap the nipple. Alloy nipples frequently fail within a year or two if the spokes are too short. Brass as well since it's only 1/4-1/3rd the strength of steel, so it may take 3-5 years.

Well.. post close-up picture of the pieces. Also take a photo of the remaining spoke & nipples in the wheel. I've seen heads shearing off on nipple with very slim heads. I prefer the DT/Wheelsmith style with a thick donut on top.

dperreno

If it's an alloy nipple then there's your problem. You're a pretty big guy, and those nipples can't take the punishment. Replace at least all of the drive side nipples with brass and I'll bet you a nickel your problems will go away.

mrrabbit 

FBinNY got the response pretty much on...how ever one correction.

***The spoke end must penetrate the RIM wall at least a couple mm's.***

Ideally if the rim were 3mm thick, then the spoke end would penetrate the same.

Bottom line is - nipples are fasteners - NOT SPOKES NOR SPOKE EXTENDERS!!! The barrels will eventually snap if you try to use nipples to make up for too-short spokes that haven't penetrated the rim wall at all.

Check the top side of the nipple...if the spoke end hasn't come up to at least a 1mm below the screwdriver flat - then a closer examination is warranted. (If the spoke end is much deeper...then you have a problem.)

Nowadays a lot of single speed wheels from the factory with 16mm nipples are running spokes to short. Rather than long-thread the spokes - the factories are instead cutting the spokes prematurely 1-2mm so that 16mm nipples can be used on 10mm spoke threads. Problem is, if the shop that sells 'em doesnt work the wheels over and tension them up considerably as they should - the barrels will start snapping. The factory is counting on the shops to finish the wheels so that 1-2mm of penetration occurs...many shops don't follow through.

Buyer beware...

=8-(

Al1943

Actually a good aluminum alloy will have as much or more tensile strength as brass.

https://www.eformulae.com/engineering/tensile.php

FBinNY 

Quibble, this isn't a correction, just a different way of saying essentially the same thing. I described the head of the nipple as the nut and said that the spoke must come 2mm into the head, something it can't do without coming through the rim wall.

Bottom line ---- like any other nuts, what happens below doesn't matter, what does matter is good thread engagement for the full thickness of the nut.

----------------------------------------------------------

BTW- a bit of history might help.

Back in the late sixties, and early seventies bikes were booming and among others Huffy was making and selling millions of bikes through mass market channels. Price competition from cheap imports was intense and margins razor thin. They needed to build wheels the cheapest, fastest way.

Up to that time wheels were built with the spokes coming fully to the top of the nipple. Of course that meant some came beyond the top, and had to be ground flush which was slow and expensive, plus using two lengths for rear wheels created it's own problems, so Huffy got an inspiration: Use shorter spokes and make up the difference with longer nipples.

Guess what, total wheel failures went from a rarity to a common occurrence and was one of the major issues cited to justify the need to establish minimum CPSC standards for bikes.

The upshot, Huffy solved the problem another way, 5/8" steel nipples.

FBinNY 

This is tricky. While there are many grades of both brass and aluminum with some overlap in tensile strengths, the options for nipple production are limited to what may be referred to as "screw machine grades" with good turning and thread forming properties.

mrrabbit 

Yeah...you're right...quibble is a good word...

Wanna grind axes...here's one thing rubbing me wrong lately. Used to be when you bought basic and replacement alloy wheels thru distributors - you pretty much got half-way decent spokes and brass nipples.

Now I'm noticing that they are still providing decent hubs and rims - but are now substituting very light weight and very shiny stainless steel spokes - (which I don't trust) - but even worse - are now slipping in brass nipples normally supplied with steel wheels. You know, those nipples that'll shed their coating just breathing on 'em, and strip in a flash and split down the side as though they were rolled and seamed...

...that quite frankly sucks nads!!!

It's Friday night...so no more gripes!

Night!

=8-)

FBinNY 

There's nothing that can't be cheapened.

From a sign at Eddies Bike Shop in the Bronx, where I bought my first Robin Hood in the Sixties.

"Quality is like buying oats. If you want nice, clean, fresh oats, you have to pay for them. But if you want oats that have already been through the horse, those come cheaper"

Sixty Fiver

Your wheel specs indicate that you are running a 20/16 setup so when one of those 20 spokes fails you're totally f'd.

Neuvation wheels are pretty inexpensive and they do say all their wheels are hand built although this tells me nothing... I have dealt with some pretty craptastic wheels that were "hand built".

I'd get better wheels under you and don't be such a weight weenie... you will be surprised to know that wheels with higher spoke counts do not have to be heavy as when you build with more spokes you can use a lighter rim whereas a low spoke wheel needs a very stiff and heavy rim to provide needed structural integrity.

One of the biggest cons that ever happened to cyclists was when they were convinced that less spokes equaled a better wheel.

FBinNY 

But they do so-o-o-o-o-o much better in wind tunnel tests at 30+ mph.

Sixty Fiver

My skinny self rides around on wheels that have no fewer than 32 spokes and those lower spoke wheels are on my mountain bike, racing bike, and my touring bike... I built all these wheels myself and have never had a failure of any kind.

All the rest have 36 or 40 spoke wheels.

achoo

I'm wondering if a set of Fulcrum wheels might work, with 2:1 lacing with double the number of drive-side spokes. I'm not having issues with my front wheel nor with non-drive-side spokes on the rear wheel. So maybe getting 16 drive side spokes with a Fulcrum 3 or Fulcrum 5 might be good enough.

Heck, I could get a whole Fulcrum 7 wheelset from Wiggle for significantly under $200 - delivered. How bad could they possibly be?

Anyone know what the freehub on a Fulcrum is made of? I'd like to get a steel freehub body given my weight.

FBinNY 

Yes, for $200.00 fro a wheelset you can't go very wrong, at least not more than $200 worth. They might serve you fairly well, but so would any correctly built pair of wheels. Also I strongly doubt you'll ever find a non-aluminum freehub body on modern hubs. There's no cost savings in production, so why would a manufacturer want the weight penalty marketing his hiubs.

I'm biased here, being a firm believer in the virtues of traditional light rim, high (32 or 36) spoke count wheels, but in your case I have two specific reasons to believe that traditional wheels will serve you better over the long haul that most or all of the pre-built specialty wheels.

First, even if all things are equalized, traditional wheels have the advantage in servicability, and can be re-built for much less than the replacement cost of factory wheels. At your weight, you'll be rebuilding or replacing wheels more often than lighter riders, so this is an important consideration.

Second, weight is such an important consideration for marketing that most wheels sold are made to be the lightest possible for the money, and designed around the needs of riders under 180#s. There might be someone building for the niche of heavier riders, or cycle tourists, but I'm not aware of them. With traditional hand built wheels you can get wheels exactly suited to your specific needs, assigning dollars spent as you prefer on the hubs, rims and spokes, and using spokes and rims suited to your weight.

bikinfool

I'm not up on road hubs for the most part, but what does your weight have to do with the freehub material? Not doubting it's a factor, just haven't seen this cited as a reason. On higher end mountain hubs they sometimes use aluminum to save weight, like on a King, but steel is offered even by King as an alternative to prevent the cassette from digging in and making it difficult to remove (I've got a few in both materials, aluminum gets chewed up pretty bad). I haven't seen weight cited as an issue, always assumed it was simply the higher torque loads.

As to manufacturers aren't Shimano freehub bodies either steel or ti? Do they use aluminum on any of them?

BTW I'm totally with Francis on just getting a quality standard 32 spoked wheel under you rather one of these silly factory wheels...

Al1943

And most of them are so-o-o-o-o-o heavy.

FBinNY 

Gee, I'm sorry.

Is it absolutely necessary to add smiley faces to sarcastic posts? I thought the so-o-o-o-o-o and the 30+ mph made my intent obvious.

Be real, how many here spend much time over 30mph? (not in the car)

Al1943

Thanks for explaining, I assumed you really were riding that fast.
Several years ago I bought a set of MAVIC Cosmic Carbone wheels with 57 mm profiles and 16 spokes per wheel. I thought they looked great on my bike. But the rims are actually big aluminum boat anchors, the profile fairings are plastic bonded to the rims, and even the spokes are heavy. Now they are wall art in my garage except for rare occasions when I participate in a flat time trial.

FBinNY 

Oh, but I do! (when the hill's steep enough). But thanks for the compliment.

There is a measurable aerodynamic benefit to the low spoke count wheels, and a drawback in terms of inertia. Riders should balance these in the context of how they ride. If they can sustain steady speeds in the 25-35mph range the aero benefit probably trumps the drawbacks. For the rest of us, low weight and inertia is probably more important.

I think that the popularity of factory low spoke wheels is probably due more to their cool factor and the lack of decent wheelbuilders, then to any real functional benefit.

achoo

Weight matters because the heavier you are, the more impact you can put into the pedals. I'm not talking about sustained force over time - the kind that translates into making a bike go fast. I mean the amount of force you hit the pedals with for a very short instant - like jumping on the pedals. Simple physics - the heavier you are, the bigger the impulse on the pedals when you jump on them or otherwise hit them suddenly and therefore the higher peak forces the cassette transmits to the freehub.

It's the sudden peak forces that do the most damage to the freehub.

Also, add in the fact that a heavier weight needs more force to accelerate it or push it up a hill. That's another way being heavier adds to the forces on a freehub.

And FWIW, Ultegra rear hubs have steel bodies.