Bicycle Mechanics - Broken Spoke

Hey all,

I have question about a broken spoke. I had my LBS build a rear wheel from scratch for me. The wheel that came with the bike was just not strong enough for me. So they gave me the "clydesdale setup". It has held up very good for roughly 1050 miles. It's stayed in true and I haven't broken any spokes. Until this morning...

I was riding on level, smooth pavement and I heard the high pitch ping. Next thing I know... the wheel is rubbing against the brake pad.

Luckily I was only about 1/2 from home so I turned around, and got my beater bike ready and rode to work on that. I took the bike into my LBS since the wheel is under a lifetime warranty. The guy that built the wheel replaced the spoke and re-trued the wheel in about an hour.

After he gave it back to me, he made the comment that it was very very strange that the spoke broke at the nipple. He said that never happens. I wasn't sure what he was implying, or even if he was implying anything. I was just wondering, did I do something wrong while riding that would cause it to break like that? Is this just an unexplained event that I shouldn't think twice about? Just let it go and be glad it's under warrant?


Thanks,

PBW

Did he build the wheel with DT or Wheelsmith spokes, hopefully? Did the spoke itself break at the inboard thread, or was it the nipple that broke?

Originally posted by mechBgon
Did he build the wheel with DT or Wheelsmith spokes, hopefully? Did the spoke itself break at the inboard thread, or was it the nipple that broke?


They are "DT 297mm 14 gauge spokes". At least that is what the receipt says.

It was the spoke that broke, not the nipple. Nipple still appeared to be intact. I looked at the end of the spoke where it broke and it looked like it broke in the middle of the threads. I saw some thread on the end of the spoke.. but not alot.

Hope that helps in the diagnosis.

PBW

Interesting... for it to break in the middle of the threads, the spoke would have to be threaded only partway into the nipple. What rim and hub do you have, and was that on the drive side or non-drive side?

Oh, and spoke count and lacing pattern too. I thought I'd calculate the proper spoke length and see if it is a case of the 297's not being long enough.

What you had happen was likely from a manufacturing flaw-either the thread on the spoke was rolled too dep, or there was a flaw in the wire stock that the spoke was made from. Possibly the threads inside the nipple were to blame. A 14-gauge spoke should be strong enough.
Most spokes break due to fatigue, and almost always break at the head, not the nipple.
If you still have the broken spoke, a high-quality close-up of the break surface would tell me if your failure was due to tensile failure (likely), or due to fatigue.

Originally posted by mechBgon
Interesting... for it to break in the middle of the threads, the spoke would have to be threaded only partway into the nipple. What rim and hub do you have, and was that on the drive side or non-drive side?


The rim says it's a Mavic T519 rim (I thought it was a Mavic 520T for some reason), Ultegra Hub, 36 spokes, 4 cross pattern. It's a 9 speed with a 12-27 cassette on it. I run it with Specialized Turbo Armadillo tires (700 x 26c).

drive side or non-drive side... mmm... I didn't pay that much attention, but I want to say drive side because when I was leaning down to look at it, I want to say it was on the opposite side I was standing, and I way standing on the non-drive side. So I'm *almost* sure it was drive-side, but I'm not positive.


I don't have the spoke and they fixed it already. But I remember that it looked like it was snapped, not bent or anything like that. It was a clean break and had a sharp edge to it. It looked like it was right in the middle of the thread, but I couldn't see what was down in the nipple still. The sound was kind of a high pitched sharp "ping". At first I thought I'd hit a rock and the tire had shot the rock away, but then I immediately felt the rim start to rub the brake pads and knew it was a spoke.

And like I said in my first post, I was riding on smooth, level, even pavement and coasting (no pedaling) when this occurred. It's been a great wheel and I'm very happy with it. I just want to make sure it wasn't something doing that caused it.

Thanks,

PBW

I know it's easy for me to be an armchair wheelbuilder ;) but I would have built that wheel with 298/299 drive/non-drive. It comes out of my spoke-length calculator as 297.1 on the drive side and experience has taught me to add a millimeter to that if it's not over 297.6. My goal is to get the spoke's threads fully engaged and get them engaged in the head of the nipple so the head isn't tempted to break off the barrel.

At any rate, I hope it was an anomoly, because it doesn't sound like there was any reason it should break. Nice wheels, good luck in the future! :)

Thanks. Sounds like this isn't something that is my fault and it's just a freak thing that occurred. I can deal with that.

It's actually just the rear wheel. Front wheel is still the stock 32 spoke rim that came with the bike. That wheel has stayed in true and not had any spokes break, so I wasn't gonna pay another $225 to have it replaced by a beefier wheel.

It rides good. Let's just hope I get at least another 1000 miles out of it before another spoke breaks... and hopefully more.

PBW

I had the same problem, spokes breaking at the nipple...about 6 of them now. I have heard all the explainations from metal fatigue to improper turing to "you didn't put grease on the places where the spokes cross."

My answer is who knows why the spoke failed...bring a couple extra and learn to lace it yourself.

When the spoke breaks, be sure to stop and wrap the broken spoke against one of the adjoining spokes, loosen the brake and look for damage to cables and components before proceeding back to the repair shop.

UPDATE:

Well I got it fixed and rode to work yesterday. Riding home was tough and I just thought it was the headwind. While I was getting the bike ready to ride to work today I noticed that the rear wheel was spinning funny. Then I notice it was rubbing the brake pads. You guessed it... I broke ANOTHER spoke. Grrrrr. This time at the opposite end. Non-drive side.

I don't get it. I hope this isn't a new trend. This tire has done great and now this. I'm just glad I have a backup beater bike.

PBW

PBW, can you peek at the heads of the spokes and confirm they really are DT's and not an off-brand or no-brand? A DT spoke will have a DT logo forged into the head of the spoke, a "T" overlaid on a "D". It is possible they really are fatiguing and breaking (14-15ga double-butted would have been better for resisting fatige) but given what I've seen 14ga. DT's stand up to, it makes me wonder if they could be not really DT's.

The non-driveside spokes are under less tension, and if the wheel is built too soft then they may undergo excessive fatigue as they lose tension, then snap taut again. How much do you weigh, and do you carry weight on the rear rack or anything?

I have had a considerable problem with breaking spokes on my road bike this summer. I have broke 3 total on the rear. I have only owned the bike for 600-700 miles.

I blame it on weight. I weight 270. I have talked about going up to a 36 spoke wheel, but really expensive for a 6 speed hub. I have an older bike, so I am weighing the difference between upgrading or buying new.

The rims are very old and beginning to show wear. There is a small bulge at one of the nipples and that has me worried. LBS said to watch it, and replace if it worsens. I think I am going to replace with mavic or something good this winter.

Also, on my last break, the guy looked at the tension and said it was way off on the non-drive side. Since it has been retensioned, it seems to be not breaking. I dunno if that fixed it?

Originally posted by mechBgon
PBW, can you peek at the heads of the spokes and confirm they really are DT's and not an off-brand or no-brand? A DT spoke will have a DT logo forged into the head of the spoke, a "T" overlaid on a "D". It is possible they really are fatiguing and breaking (14-15ga double-butted would have been better for resisting fatige) but given what I've seen 14ga. DT's stand up to, it makes me wonder if they could be not really DT's.

The non-driveside spokes are under less tension, and if the wheel is built too soft then they may undergo excessive fatigue as they lose tension, then snap taut again. How much do you weigh, and do you carry weight on the rear rack or anything?


I will check the spokes out when I get home. I'm taking it into the shop tonight to get it fixed. I haven't had a chance to get the spoke fixed the last two days. I seem to remember looking at the end of the spokes seeing some kind of design on them, but I can't say for certain if it was a DT logo. That probably doesn't mean much.

I am a clydesdale. I weight in at about 280 and I carry a bag with me with my clothes and stuff in it. I would say the bag is about 10 or 12 lbs. So I'd say there's anywhere from 290 to 295 lbs on the bike at any one time. I've been trimming down alot since I started riding, in fact I had to go buy smaller biking shorts recently. But I'm gaining as much muscle as I'm losing fat I think, so overall I've only lost about 10 lbs since March. I am able to ride faster and go farther. My avg speeds are going up all the time. Ultimately I would like to get down to about 210 or 205. I've got a long way to go.

I asked if this was the strongest wheel I could get, and the wheel builder said "pretty much". There are other options but they get really pricey. I thought a $225 wheel was bad enough. I'm not about to spend $600+ on a wheel, especially since the bike cost $1400 total.

I'm gonna ask about fatigue when I have them fix it tonight. I'll keep ya posted.

PBW

PBW, I have very similar wheels -- T519's with 36-hole Ultegra hubs, although with Wheelsmith 14/15 spokes and bigger tires (700x32c).

I agree that it sounds odd that the spoke would break within the threads, and wonder how that is possible unless some of the threads are exposed. They shouldn't be, and if they are I agree that the builder might have used too-short spokes.

I weigh 210 (come on, you guys! "weigh" is the verb; "weight" is the noun! :) ) and carry a fair amount of cargo on my commutes, and these wheels have been solid for the 6000 miles I've ridden them.

A well-built wheel will not break spokes unless it's subjected to trauma. The wheel needs to be properly tensioned (ask the builder to show you his tensionometer) and -- critically -- the spokes need to be stress-relieved (that's where you go around the wheel and squeeze pairs of spokes with your hand to "untwist" them after they've been installed). Once this and a final truing is done, there's no reason a quality wheel shouldn't stay true and trouble-free for tens of thousands of miles (if you don't abuse them).

Question the wheelbuilder about his technique. You have the right; it's your money. It's certainly possible you just had a defective spoke, but from your description I suspect a too-short spoke, possibly undertensioned, with a lot of stress still in it. That combination could conceivably cause the break you describe in a non-defective spoke.

RichC

UPDATE:

They are DT spokes. I checked the spoke heads, and they have the DT logo.

A different guy was there tonight (at the LBS) and not the originial wheelbuilder. This guy has worked on my bike once before and did a good job so I trust him.

He said this spoke probably went because the other spoke went and this one got more or less tension suddenly. He said it's not uncommon for spokes to go in pairs. He fixed it up and checked all the other spokes. Said they looked very good and he wasn't sure what caused it. I haven't hit any major bumps or anything lately. He asked me to bring it back after about 15 hours of riding so they could re-check it.

So, hopefully this gets me back on the road carefree again. The guy tonight said getting around 1050 miles out of the tire before a spoke break was pretty good. I didn't think so. But oh well.

Thanks all for the help and advice.

PBW

Originally posted by P. B. Walker

So, hopefully this gets me back on the road carefree again. The guy tonight said getting around 1050 miles out of the tire before a spoke break was pretty good. I didn't think so. But oh well.


It's a load of bs, and I wouldn't think much of a bike shop that tried to shovel it at me.

RichC

Originally posted by Rich Clark


It's a load of bs, and I wouldn't think much of a bike shop that tried to shovel it at me.

RichC

I agree with ya. However, they are the best shop in town. I don't think the guy I usually talk to would say something like that or even think it. In fact, he wasn't too happy when I brought it back for the first spoke. The guy that said that is a part time mechanic. I've only seen him in there 2 or 3 times before. I have a feeling he was just trying to make me happy... which isn't right either I know.

At the very least, the wheel is warrantied for life, so if it keeps breaking, they have to keep fixing it. But it is a hassle, timewise, to have to go there to get it fixed everytime.

PBW

Perhaps the 4X lacing pattern is part of the problem. Although it makes the spokes more tangential to the hub, thereby reducing torque-related breakage at the head end, it also makes the spokes less radial at the rim, thereby increasing the stress at the far end. With low- or mid-flange hubs, many builders recommend 3X as the best overall compromise.

I have built a few wheels and had some spokes break before. A normal 32 spoke, 3 cross bicycle wheel is usually made for carrying less than 200 pounds. The 4 cross pattern will spread the load over more spokes than a 3 cross pattern. A spoke is weakest at the head and second weakest at the threads.

The first spoke may have been caused by a manufacturing defect or too heavy a load. If fatigue is the problem, it will break at the head. The second spoke was almost definitely caused by too high a load (assuming the spokes were properly tensioned). I have had several drive side spokes break, but only one non-drive side spoke, and it was when I was commuting with panniers and standing in the pedals.

Some things that will help your situation would be to use 40 spoke wheels with double butted (14-15-14) spokes, or at least change the spokes on the current wheel to double butted. The advantage of the double butted spokes are that they distribute the tensile stress along the entire length of the spoke instead of concentrating it all at the head and the threads. After breaking two spokes on the same wheel, it may be time to take it back to the bike shop and have him rebuild the wheel (instead of just replacing the spoke). This will ensure that the spokes are properly tensioned.

Hope you can get this worked out.

Update:

Well last I reported, a temp mechanic had repaired a broken spoke. He told me to bring it back after putting some miles on it so they could check it. I put about 50 miles on it and since I had to go to the shop anyway, I took it back in. The regular guy was there and didn't like the setup so he re-trued each wheel and checked all the spoke tensions.

Well got about another 70 miles on it and now a few spokes are loose and the wheel is so out of true the rim is rubbing the brake pads.

Grrrr...



How hard is it to learn how to build your own wheels? Can you teach yourself or would ya need to take a class? What equipment is needed?


I'm almost afraid to go for rides anymore because I don't want to get broken or loose spokes halfway into a ride.

PBW

Originally posted by P. B. Walker
Update:

...

Well got about another 70 miles on it and now a few spokes are loose and the wheel is so out of true the rim is rubbing the brake pads.

The wheel was undertensioned.


How hard is it to learn how to build your own wheels? Can you teach yourself or would ya need to take a class? What equipment is needed?

Like most things, it's a little tricky the first time you do it, but it is not rocket science. Have a look at:

http://www.sheldonbrown.com/wheelbuild.html

to get an idea of what's involved. A good book on the subject is 'The Bicycle Wheel' by Jobst Brandt. When you are done with it, consider lending it to the shop!

I build wheels using the frame or fork and rim brakes. The only disadvantage is that it takes longer. You can pick up a Minoura or Park stand for about $50-70 US. You will also need a spoke wrench - don't use one of those round multi position ones, get a decent one (this is covered in the URL I posted above).


I'm almost afraid to go for rides anymore because I don't want to get broken or loose spokes halfway into a ride.

PBW [/B]

I don't blame you!

You could try increasing the tension and stress-relieving the wheel you have now to find any other spokes which are hanging by a thread and replace just those ones or you can start over with new spokes. Unless the rims are super-lightweight or damaged (unlikely) they should be fine.

bikerider,

thanks for all the info. I checked out that website... wow. Lot's to read. :) I think I'll take it into the shop once more and have them fix it up, then I'm going to look into doing it myself.

Thanks for the info.

PBW

The Bicycling Maintenance book (I forgot the
actual title) has a good section on wheel building,
with some very good photo's.
I just built my first set of wheels (back in July?)
and rode them the rest of the summer.
Its not too difficult, and there is some really
good information here if you ask.

There is also a tremendous amount of pride
in riding wheels that you built yourself.

Marty

Well I read Sheldon Brown's website regarding wheel building and you are right, it's not rocket science. Seems like you just need the time and some patience. I did want to ask what you all think about two things:

A) Triple-butted spokes: I believe I have double-butted, but I'm not positive. According to Sheldon, the primary aim of triple-butted is durability and reliability. Since this is my commuting bike during the summer and I'm a clydesdale, I figured I fit into this category. Plus, this is the type of spoke used for tandems and loaded touring. While I don't do much loaded touring, I am on the heavy side and I carry around 12-15lbs of stuff when I commute. Is there a real advantage to triple-butted spokes, compared to the double or single butted?


B) Going from a semi-tangent, 36 spoke, 4 cross pattern to a Half-radial spoking on the rear wheel. This is one of the specialized spoking patterns Sheldon mentions where the drive-side spokes are kept in their normal semi-tangent, 3 or 4 cross pattern, but the non-drive side spokes are done in a radial pattern (i.e., straight out from the hub to the rim). If you go to the link provided above and go down to Half-radial Spoking, you can read more about it.


I'm contempating asking the mechanic at my LBS about these two items, but if they are silly, or not worth mentioning, then I don't want to even bring it up to him. He can be a tad bit... "testy" when you question his work. :)

Thanks in advance,

PBW

Originally posted by lotek
The Bicycling Maintenance book (I forgot the
actual title) has a good section on wheel building,
with some very good photo's.
I just built my first set of wheels (back in July?)
and rode them the rest of the summer.
Its not too difficult, and there is some really
good information here if you ask.

There is also a tremendous amount of pride
in riding wheels that you built yourself.

Marty

I have this book... I think. I'm positive the one I have is from bicycling magazine, but I'm not sure of the exact title. Anyway, I've mainly just used it for the basics. I think it's buried in my desk someplace at home. I'll dig that out and have a look at the section on wheel building.

Thanks,

PBW

P. B. Walker

It is not that hard to learn to build wheels. I would, however, stick with the regular 32 or 36 spoke 3 cross pattern for the first try. Sheldon Brown's website is where I learned to build wheels and he goes over this in detail (not much difference in building 32 or 36 spoke wheels. He covers both).

Also a note about spokes. I don't think there is such thing as a triple butted spoke. The "butted" is refering to the two ends of the spoke, which in a double butted spoke, are both thicker than in the middle. Double butted, 14-15-14 gauge spokes are about the strongest that you will find. They are even stronger (though not as stiff) as straight 14 gauge spokes because they distribute the stress away from the elbow of the spoke, where it is most likely to break. The LBS should be able to help with the spoke length and acquisition. The spokes should be either DT or Wheelsmith brand.

I would also suggest getting a truing stand if you embark on this project. The brake pads work, but a truing stand will make the work easier.

If you can build your own wheels, it is a wonderful feeling of accomplishment. It will teach you not only how to build a wheel, but also how the wheel works. You will be able to true your own wheels, and judge for yourself if the work the shop did was adequate.

Sorry, my bad. There is a triple butted spoke with each end a different diameter. The double butted should work just fine though.

PBW,

I agree with Brian.
I'd start with a 3x wheel (doesn't really matter how
many spokes, the builds basically the same). It
is the standard that all the other wheels build from.
I don't know about all that radial spoking stuff
but I do know alot of hubs will have warranties
voided if you build with radial lacing (if that matters).

Let us know how you do with you're new project.

Marty

PBW,

best of luck with wheel building. I've been in the same situation: trying to ride "lightly" (whatever that would mean), watching out for every little bump in the road because I'm so afraid I'll break yet another spoke.

With help from this Forum and other web sites mentioned above I am now able to replace a spoke myself and true the wheel. I'm not particularly fast or seasoned at it, but I get the job done. I have not yet needed to build a wheel from the scratch, but will try it when I need a new one.

So go for it, you'll get a better understanding of your wheels and a great sense of accomplishment. And to other posters here: thanks for all the advice and words of encouragement. Ride on!

:beer:

--J