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Discussion Starter · #1 ·
Third time in less than 100 miles, always on the left rear side (possibly the same spoke? -- I should have marked it).

The wheels are made by Chris King. The spokes are Sapim CX-Ray. The guy at the bike shop who repaired the first two told me Sapim are crap spokes and to rebuild the wheel. I don't know anything about spokes, but this struck me as slightly implausible. I've ridden on them for over a year and a half with no issue whatsoever, but my wife's bike fell on mine in the car and the first spoke popped, and apparently either weakened other ones or the bike shop is doing something wrong. In any case, it is making riding unpleasant, so I want to get this fixed once and for all. I understand these things happen, but 3 in a row in a few weeks of light riding, all on the left rear side, is not a coincidence (seems like every other spoke I've busted on other bikes is always the right rear).

Do these spokes suck? I ride hard, often on rough trails. I weigh about 190. Lately I have been doing a lot more standing up on the pedals, and for the winter have put 40 mm tires on. So I may be just exceeding the capacity of these spokes, but I just don't know enough to make an informed decision. Should I have the wheel rebuilt, and if so with what kind of spokes? The bike is steel, the rims are aluminum, and I am not terribly concerned about increased spoke weight. I just want something reliable. Also, should I have Chris King do it? (I don't even know if they do this kind of thing, but I have to be in Portland in two days, so it is tempting...)
 

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I'm inclined to think the cause was the wife's bike falling on your bike.

The Sapim spokes are 18/8 gauge steel; that's pretty much standard across the brands.

Some builders do have better luck with one brand over another; I prefer DT Swiss for example, because I've never had a problem with them so why change?!

Yeah; usually the drive side spokes break because they're under greater torque loads, but all spokes fail from long term fatigue, not from sudden overloading, except when you hit a car-don't ask me how I know...

The Sapim's are 14 gauge which on the surface suggests they're meaty enough. But the fact that the center section is flattened, and the transition from flat to round at the ends is pretty abrupt, leads me to speculate the flattening may make the spokes more brittle (although I have no proof of this) and the abrupt transition from flat to round may create stress risers. I like plain, round spokes.

If the spokes are breaking at that transition, then it must be the spokes. If they're breaking at the elbow or threaded end, it's fatigue.

Usually for me it's "three strikes, you're out" so at your point in the game I'd replace all the spokes in the wheel with basic 15 or 14 gauge DT or Wheelsmith spokes. Double butted spokes purportedly lead to longer lasting wheels due to the elasticity of the center section of the spoke but I can't tell much difference except in my wallet.

I don't feel your weight is exceeding the limits of the Sapim spokes. Wheel construction quality has more to do with durability than the components which at your level you're already likely running brand name rims and we already know the hubs and spokes. Good stuff.

Losing the one spoke did not suddenly make the remaining spokes weaker and subject to breaking. Don't worry about that.
 

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Discussion Starter · #3 ·
If the spokes are breaking at that transition, then it must be the spokes. If they're breaking at the elbow or threaded end, it's fatigue...

Losing the one spoke did not suddenly make the remaining spokes weaker and subject to breaking. Don't worry about that.
This one broke right at the elbow; definitely not at the transition. I am almost certain it was the same for the previous two.

I do wonder if it the same spoke, and they replaced it with something inferior. I wish I had marked it. I can't see an obvious difference.

(The rim is HED Belgium Plus Disc, fwiw.)
 

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First of all, Sapim spokes are not crap. Some builders like your LBS, do a crappy job with them but they would have done so no matter what spoke they used.
My take on your story is that your LBS messed up the tension balance on the wheel when he replaced the two spokes that originally broke. Most probably he trued the wheel without equalizing the tensions and maybe he did not stress relieved the spokes either. When you started riding the wheel, the tensions equalized because this is what they do, some spokes did not have enough tension to keep them in their elastic region and eventually broke. Being on the left side its further proof on this.
Before doing anything else on the wheel, I would find a competent wheel builder and have him look at the wheel. It's quite possible you only need to replace the broken spokes and retension the wheel, if he knows what he is doing.
 
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Discussion Starter · #5 ·
That sounds plausible.

When spoke #1 broke, nothing moved. I was not on the bike.

When spoke #2 broke, the wheel immediately moved the the right so much that the (40mm) tire rubbed the frame.

When spoke #3 broke, I was able to ride it downhill (mostly) for about 8 miles. There was a slight amount of rubbing, but by inspection the wheel did not move as far from its original position.

I think finding someone competent to rebuild it will be the challenge... I really wish I knew how to do this, but I get the feeling it is not a skill you can pick up overnight.
 

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How are these wheels laced and what spoking? I didn't see mention-but tubeless tires?

Sounds like the build design isn't working for you.
 

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Discussion Starter · #7 ·
How are these wheels laced and what spoking? I didn't see mention-but tubeless tires?

Sounds like the build design isn't working for you.
The Chris King page I linked to has more info, but hopefully this answers what you are asking. (The tires are 40mm Clement Xplor clinchers). Wheels worked flawlessly for the first 19 months.

Rim Type:
Clincher/Tubeless Compatible
External Width (mm):
25

Internal Width (mm):
20

Rim Depth (mm):
24

Hub Configuration:
28/28 R45D


HUB Options:
Shimano , QR/12/15 and 142x12

Spokes:
Sapim CX Ray


Nipples:
Alloy Black, Alloy Silver or Brass Silver

Lacing Pattern:
2-Cross
 

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I think finding someone competent to rebuild it will be the challenge... I really wish I knew how to do this, but I get the feeling it is not a skill you can pick up overnight.
Finding a good builder is a challenge. I would look for builders who build wheels for a living, not wrenches at the bike shop who also build wheels. It may be an unfair generalization but unfortunately holds generally true.

If you wish you knew how to do this, take the dive and do it. You won't regret it and is a very good skill to have. Incidentally, that's how I was motivated into wheel building. The wheel built by my LBS would not stay true after each and every 40 mile ride. After 4 consecutive attempts at the LBS to fix it failed miserably, I bought the tools and did it myself. I still have that wheel and it has stayed true.

There are enough resources and knowledgable folks on this forum to help you along the way if you decide to take the plunge.
 

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The Chris King page I linked to has more info, but hopefully this answers what you are asking. (The tires are 40mm Clement Xplor clinchers). Wheels worked flawlessly for the first 19 months.
The 20x24 rim used and the number of spokes chosen are plenty for your weight. Don't look at the build. IMO it's the repair job that took you in.
 

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The Chris King page I linked to has more info, but hopefully this answers what you are asking. (The tires are 40mm Clement Xplor clinchers). Wheels worked flawlessly for the first 19 months.
Derp. Just realised that, didn't see those as expandable.

Clinchers versus tubeless matters, because when you inflate a tire on a spoked wheel it induces a measurable tension drop in the spokes. Pull out your Park spoke tension gauge and you can see it. What is fun, is that tubeless tires measurably inflict more spoke tension drop than standard clinchers-again you can see it with the Park tension meter.


I had a set of King 28h/28h R45 hubs laced to Belgium+ rims radial front and 2X rear with CX-Rays. The rear popped spokes once, rebuilt 3X with CX-Rays. Rear popped again. After that I had it rebuilt 3X with standard triple-butted DT spokes and no issues since.

You're due for a wheel rebuild no matter what.

CX-Rays in 2X with 28h lacing are not for you, is my opinion. I'd go for a standard quality-butted spoke in 3X. Also being disc wheels, they're subject to more unbalanced forces than rim-brake hoops.
 

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First of all, Sapim spokes are not crap. Some builders like your LBS, do a crappy job with them but they would have done so no matter what spoke they used.
My take on your story is that your LBS messed up the tension balance on the wheel when he replaced the two spokes that originally broke. Most probably he trued the wheel without equalizing the tensions and maybe he did not stress relieved the spokes either. When you started riding the wheel, the tensions equalized because this is what they do, some spokes did not have enough tension to keep them in their elastic region and eventually broke. Being on the left side its further proof on this.
Before doing anything else on the wheel, I would find a competent wheel builder and have him look at the wheel. It's quite possible you only need to replace the broken spokes and retension the wheel, if he knows what he is doing.
:thumbsup:

If it were my wheel, at this point I'd replace the spokes on left side, re-true, retension, and stress-relieve the new spokes, and most likely you'll be good to go.
 

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@ Marc

2x or 3x lacing does not affect spoke longevity. Spoke line alignment does and it's more forgiving if it's not done properly with 3x than 2x.
Triple butted spokes add a bit more insurance at the elbow.
 

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@ Marc

2x or 3x lacing does not affect spoke longevity. Spoke line alignment does and it's more forgiving if it's not done properly with 3x than 2x.
Triple butted spokes add a bit more insurance at the elbow.
A wheel not lasting 100 miles isn't about "longevity" as either not being built well to start with or not being built adequately to the rider and their riding. I'll give King the benefit of the doubt that they can build a wheel....although you can double check their work with a Park guage.

Maybe CX-Ray spokes aren't what they used to be, that could be too.
 

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A wheel not lasting 100 miles isn't about "longevity" as either not being built well to start with or not being built adequately to the rider and their riding. I'll give King the benefit of the doubt that they can build a wheel....although you can double check their work with a Park guage.

Maybe CX-Ray spokes aren't what they used to be, that could be too.
Per OP the wheel lasted for 19 months, trouble free, before the incident with the wife broke the spokes that caused the repair and the beginning of the end.
At this point it's too late to check King's wheelbuilding quality because the LBS messed up the tensions when truing the wheel.
Spokes typically break at the elbows for two primary reasons - lack of tension and/or lack of support.
 

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Discussion Starter · #15 ·
Pull out your Park spoke tension gauge and you can see it.
I take it I should own one of these? The only wheel tool I have is a $2 spoke wrench... (ok, maybe some cone wrenches).
 

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Riding up steep climbs in low gear, especially standing, put a lot of stress on the rear wheel. I'm all of 145 lbs and I had to learn how to build wheels in order to get a wheel that lasts with the large amount of climbing I do. For a while I was getting my rear wheel rebuilt every 9 months.

It's possible that the wheel was built with the tension a little too low. Or the tension was lowered during the first repair. With three broken spokes I'd consider this wheel build finished. If it were mine I'd replace the spokes and rim. The rim will have accumulated some fatigue and will have a shorter life, potentially shortening the new wheels life.

NDS spokes breaking at the elbow is a classic too little tension problem. It takes a while for the spokes to fatigue enough to start breaking (9 months for me is about 6000 miles and 600,000' of climbing), so it could well be from the original build. BTW Sapim makes good spokes... the guy who said they're crap is wrong. I personally think they're a little better than Wheelsmith or DT, but they are all good.
 

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Discussion Starter · #17 · (Edited)
Thanks. I'm sort of at the final (?) stage of recover from a nasty ankle break (sig link) and am only now able to really stand up and hammer on steep hills. My average ride is 105 ft/mile closed loop (so double that for the uphill) and I'm concentrating on pushing it, so it well be a factor in addition to accumulated fatigue.

Anyway, I am resigned to having the wheel rebuilt and just need to find the best place to do it.
 

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Unfortunately, it's also possible that the shop did as good a job as they could, but the wheel suffered damage that makes it difficult or impossible to achieve both even tension and trueness. If the rim was bent (possible in the kind of accident you describe), it can take uneven spoke tension to pull the wheel into round, and continued spoke failures are likely. A good wheelbuilder can evaluate that.
 

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Discussion Starter · #19 ·
I'm hoping it wasn't that. It was just her bike flopping over in the minivan when I went around a turn, so it shouldn't have been that much impact.

I'll call Chris King tomorrow and see if they would be willing to do it, and then I can take the wheel as my carry-on, along with my laptop. I'm sure TSA would be delighted.
 

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I think finding someone competent to rebuild it will be the challenge... I really wish I knew how to do this, but I get the feeling it is not a skill you can pick up overnight.
wg, who really knows what's going on here. Numbers 2 & 3 could have broken from wheel fixing incompetence. If the LBS person told you that Sapim spokes are crap then I wonder what else he doesn't know about spokes and wheelbuilding. There are three top spoke makers and they're all so equal that it doesn't matter what you use.

Yes, the problem is finding a wheel person who is not a bluffer. A retail store and possession of a spoke wrench is no proof of competency. You can learn to build (or rebuild) them yourself and I've dealt with hundreds of people who build their first wheels - and perfectly acceptable wheels too. Read my site, follow its links (especially the one to Roger Musson's fine e-book) and jump right in.

Don't bother with buying CX-Ray spokes as, for most of us, their aero benefit is not worth the cost. Use good old Sapim Race at 1/3rd the cost.
 
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