Habitual spoke breaker
 

Hey all,

Just trying to get some ideas. My dad has become a habitual spoke breaker. He has had his rear wheel replaced 3 times and has broken probably 6-10 spokes total.

The wheel has been tested, trued, tensioned etc.

He rides a comfort bike (2005 Jamis Aragon) and is not a small guy, about 250-260lbs. He has lost over 100 riding though :)

The bike shop was telling him it is due to torque because he cross chains too much. He spends almost all of his time in the big chainring, even down to the biggest cog and can mash the pedals pretty hard. So the LBS was saying that when he is crosschained like that and pedalling hard he is causing too much lateral torque on the hub which is causing spokes to break.

Does that sound like a feasible answer? His wheels seem sturdy enough (36 spoke count). And I know he is getting frustrated by this problem.

-D

any one over 180 lbs will have spoke issues in there life if it is a machined wheel you will have more problems then hand built also depends pn how you take pot holes and if you jump over things and roll over things and if the rodes are horrible

Well the roads aren't horrible. Most of his riding is on the same Rails to trails path. Pretty smooth and well kept, also flat.

-D

spoke problems are generally caused by crappy spokes and wheel builds, not by weight. tandems would never work if this were true.

heres the key: get a good decent rim, nothing fancy, like a sun cr-18, 36 hole. build it up with wheelsmith xl 14 spokes, which are butted, which makes them stronger, in fact they were developed for tandem use, not weight savings. use a good hub, anything by shimano will work if on a budget, a phil wood if you can afford it. your dad needs to change bike shops. they obviously know nothing. telling a blatant lie like you cross chains too much is ********. that has nothing to do with spoke breakage.
if he doesnt have a good local shop, call peter white, who makes wheels for tandems all the time, and knows all about good wheels that dont break. peterwhitecycles.com

That was my feeling and what I was trying to tell him. But he is super loyal to this LBS and even my mention of having someone else check the wheels is near heresy.

-D

Are most of the spokes he breaks on the left side? These tend to fatigue quickly on 3X-laced rear wheels because they become unloaded and re-loaded as the rider pedals... this is exacerbated by hard mashing and maybe cross-chaining, although that last part sorta sounds like BS to me.

A 36-spoke wheel properly built is really very strong. Strong enough to hold a small pyramid of circus clowns. Definitely strong enough to hold your dad! A few suggestions:

* Try another shop. Maybe the wheelbuilders at the shop you've beesn using aren't very good or do the job too hurriedly.
* Try double-butted 14/15/14 spokes rather than straight 14-gauge spokes if you don't have them already. They're more elastic and thus resist jolts better. (See here for why: http://sheldonbrown.com/wheelbuild.html#spokes)
* Try having the rear wheel laced half-radial: this tends to reduce fatiguing of the left-side spokes. (read this: http://sheldonbrown.com/wheelbuild.html#half-radial)

Rims make no difference whatsoever. Number of spokes, hubs and gauge of the spoke make far more diffence. Don't go with a straight gauge spoke. Go with a double butted or, my favorite, a DT Swiss Alpine III.

Here's the argument from Sheldon Brown

Double-buttedspokes are thicker at the ends than in the middle. The most popular diameters are 2.0/1.8/2.0 mm (also known as 14/15 gauge) and 1.8/1.6/1.8 (15/16 gauge).
Double-butted spokes do more than save weight. The thick ends make them as strong in the highly-stressed areas as straight-gauge spokes of the same thickness, but the thinner middle sections make the spokes effectively more elastic. This allows them to stretch (temporarily) more than thicker spokes.

As a result, when the wheel is subjected to sharp localized stresses, the most heavily stressed spokes can elongate enough to shift some of the stress to adjoining spokes. This is particularly desirable when the limiting factor is how much stress the rim can withstand without cracking around the spoke hole.


Triple-butted spokes, such as the DT Alpine III, are the best choice when durability and reliability is the primary aim, as with tandems and bicycles for loaded touring. They share the advantages of single-butted and double-butted spokes. The DT Alpine III, for instance, is 2.34 mm (13 gauge) at the head, 1.8 mm (15 gauge) in the middle, and 2.0 mm (14 gauge) at the threaded end.
...Triple-butted spokes solve one of the great problems of wheel design: Since spokes use rolled, not cut threads, the outside diameter of the threads is larger than the base diameter of the spoke wire. Since the holes in the hub flanges must be large enough to fit the threads through, the holes, in turn are larger than the wire requires. This is undesirable, because a tight match between the spoke diameter at the elbow and the diameter of the flange hole is crucial to resisting fatigue-related breakage.

Since single- and triple-butted spokes are thicker at the head end than at the thread end, they may be used with hubs that have holes just large enough to pass the thick wire at the head end.

I've used the Alpines on my mountain bike for around 5 years and haven't had any problems with them. I'm not that much lighter than your Dad, derath and I ride my bikes hard, so I think the Alpines will stand up to his riding. I've built wheels for my touring bike using the same spokes for exactly this reason, because there the weight of me, bike and gear can push 300 to 325 lb pretty easily.

Hmm,

Well I was looking at his prior wheel. He had given to me as a project. I have been wanting to try a wheel build. I have all the stuff I need.

It is a shimano hub and an alex rim. Dunno the exact models as I am giving my daughter a bath and had just enough time to run down and look real fast.

Definitely looks like straight guage spokes. maybe I will get some better spokes and try my hand at building him a wheel. Couldn't hurt right?

-D

Definitely couldn't hurt :) Give it a try building him a wheel. I've used Wheelsmith only because Nashbar has them really cheap, and lotsa smart folks seem to prefer them. Others prefer DT Swiss. Those are the two big brands for highly regarded spokes.

Sheldon Brown's wheel building guide is great. The first time I did it, I sat in front of my computer and followed along step by step with the rim, spokes, hub, and tools at my side. Took me about 2 hours to build a very solid wheel that never broke a spoke.

ok so according to you, rims make no difference. so what your saying is this fellow would be just as well of on a single wall weinmann, or a super lite racing rim, as he would on a triple box touring rim. thats ********. the rim might not be as important as spokes, but to say its not even worth thinking about... also, if you knew anything about spokes, you'd know dt spokes are built to slipshod machine building tolerances, and that i already recommended a 14/17 gauge spoke by wheelsmith.

Your main problem seem to be summed up right here. If the LBS doesn't have a competent wheel builder (and it seems they don't) there is nothing you can do.

My take is that habitual spoke breakage is due mainly to inadequate initial spoke tension when the wheel is first built. All of the other factors (rim choice, spoke configuration, etc.) are secondary.

We can keep this civil or we can insult each other. Which will it be? I made no statement that is '********'. In terms of spoke breakage, the rims have nothing to do with the problem. And yes, in terms of spoke breakage, he would do just as well on single wall rims or a light weight racing rim or touring rims. (Light, as in light weight or a light beam or light salad dressing is spelled L.I.G.H.T ) In terms of overall wheel strength, the rim plays a part but not in terms of spoke breakage. However, as a heavy fellow (who also knows the rules of the English language and practices them, such as capitalization), I've ridden light weight rims and single wall rims without problems either in terms of spoke breakage or in terms of rim breakage.

As for DT Swiss spokes, I guess they are so bad that no one carries them. I mean they are so very hard to find. By the way, Wheelsmith (notice that capitalization stuff again) doesn't make a 14/17 gauge spoke. Perhaps you were confused and meant 2.0mm/1.7mm/2.0mm, which is a 14/15 gauge spoke. Apparently your knowledge of spokes is, shall we say, lacking.

A 14/17/14ga spoke is probably not strong enough for a heavy rider. I would say use 14/15/14ga for a heavy rider, since they're about as strong as straight 14ga spokes and yet more elastic and thus fatigue better.

I'd disagree on the rim's importance in spoke fatigue. Consider that a stiffer rim won't cause the spokes to fluctuate tension as much as the wheel rolls.

They're a lot easier to build and to get even tension with too.

+1

Maybe he ought to drop for an Aeropsoke wheel for the back. bk

+ one kazillion to the 4th power times 3hree. Then add one.

Of course rim stiffness has something to do with the strength of a wheel.

I have no idea why this old thread got dredged up but please read what I said. Rims are important to wheel strength but in terms of spoke breakage -the point of the original post - they are of little importance. A crappy rim can be built into an absolutely beautiful wheel and a wonderful rim can be built into the most horrible wheel in the world. It depends more on the spoke and the spoke tension then on the identity, or strength, of the rim.

The one caveat I will put in here is that this holds for 'normal' count wheels, i.e. 32 hole and above. I have no experience with low spoke count wheels but I do know that the rim plays a much more important role there since the loads at each spoke on the rim must be higher.

Yeah, by this time when the spokes are breaking constantly, the rim makes no difference anymore. It was all due to the initial tension being too low.

This is odd advice, some good...and some not!

First off he's right about the 36 spokes but wrong about using straight gauge 14, it's been proven that double buttes spokes are actually stronger and DT Competition work great and for his weight get the 2.0/1.8 gauge for the least amount of problems. The Sun ME14A is similar to the CR18 but the ME14A is a road bike rim whereas the CR18 is a MTB rim; also Velocity Aerohead O/C is an odd design but that design makes it a strong rim, otherwise just the Aerohead (without the O/C) is also very good.

Phil Woods hubs are probably the best hubs on the market but cost $250+ each but they don't make the spokes last longer although the hub will way outlast the spokes and rims.

Peter White is a very good wheel builder and amoung the best in the world and if you want him to build your wheelset then by all means contact him; his prices are reasonable considering what he can do to a rim. He can also give you advice about lacing the spokes which 3x is usually recommended; and whether or not to use brass or alloy nipples.

Your dad is not going to be able to get the lightest wheelset on the market, but he can get one that he can ride without worries.

i'd like to see proof of double butted being stronger.

anyway as far as your bike shop goes the torque thing is BS. he'd create way more torgue if he shifted onto the granny ring.

a decently built 36h may well be strong enough for him. but i'd go with a with a 48 tandem hub spaced for 135mm just to be sure. the extra 12 spokes and nipples weigh only a few ounces more, a worthwhile trade off for a wheel that'll be 33% stronger.

Well, DB is not necessary stronger, but it builds a more durable wheel that doesn't go out of true as easily. It as to do with the elasticity and a straight-gauge spoke isn't stretched as much at the same tension. So when the rim flattens out at the bottom under load, the straight-gauge spoke can lose all tension while teh more-stretched DB spoke still has some. This keeps the nipples from rattling and loosening and the wheel stays ture longer with DB.

But as far as strength and snapping, I'm not sure, I suppose that it's more a function of tension.

I assume that stronger = more fatigue resistant in this context?
http://www.sapim.be/index.php?st=pro...il=fatiguetest is first off the rank in a Google search

what does that fatigue test mean, it's pretty blurry.

i'm not conviced about the whole stretching thing. by allowing the rim to deform more, as it's suggested db spokes do. then you are letting the unloaded spokes become even more unloaded. and then you have the whole fatigue resistance of the rim leading to cracking.