Broken spokes

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Broken spokes

Postby wizardhat » Mon Oct 22, 2012 8:30 pm

I had a spoke break on my rear wheel last week on the drive train side. I took it to the LBS and all seemed well until I was caught pump-less at work today and had to use a co2 canister to top my tires off after forgetting to do so this morning. I've heard (can't remember where now) that it's a good idea to deflate the tire to remove the co2 and re-inflate it as the co2 will escape the inner tube and leave you with a flat - don't know if this is true or not but as I was putting some fresh lube on the chain I figured I may as well change the air in the tires as well.

Anyway, when I deflated the inner tube a spoke snapped! That can't be right, can it? It had no load on it whatsoever. It's a different spoke to the one that broke the first time, but still on the drive chain side. The wheel is a Specialized(?) Rival Fuser SL that came with the bike when I bought it a few months ago.

I weigh around 90kg so I'm not the lightest bloke but neither am I the largest, nor am I particularly powerful on the bike so it seems odd to me that the spokes could have broken due to use. I've read the sticky on wheels and it made me think that the spokes might have been over tensioned and the inflated inner tube was counter acting the excess tension, so when I fully deflated the tire the spoke couldn't take it any more.

Should I ask for the wheel to be fully rebuilt? Should I ask about a wheel with more spokes? Is this just something that happens with road bike wheels? As you can probably see I am pretty clueless when it comes to wheels so I would appreciate any advice before I take the wheel back to the LBS.
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by BNA » Mon Oct 22, 2012 8:31 pm

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Re: Broken spokes

Postby wizardhat » Mon Oct 22, 2012 8:31 pm

Ugh phone changed roval to rival and fusee to fuser!

Sent from my HTC One X using Tapatalk 2
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Re: Broken spokes

Postby jacks1071 » Mon Oct 22, 2012 9:30 pm

If you start blowing spokes one after another its usually an indication that the spoke tension in the wheel is uneven.

Assuming your rim isn't bent for instance, a rebuild is most likely in order.

I'm not sure what your wheels are worth but you should look into their value before spending $$ on the re-build as sometimes for not much more money you can get a brand new set.
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Re: Broken spokes

Postby Ross » Tue Oct 23, 2012 11:39 am

Even if you buy a new set of wheels it's a good idea to check the tension of the spokes first rather than just chuck them on and ride of into the sunset.
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Re: Broken spokes

Postby wizardhat » Tue Oct 23, 2012 1:23 pm

Thanks for the advice folks. What is the best way to check the tension is correct? Do I need a tool?
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Re: Broken spokes

Postby ironhanglider » Tue Oct 23, 2012 3:47 pm

wizardhat wrote:I had a spoke break on my rear wheel last week on the drive train side. I took it to the LBS and all seemed well ...

Anyway, when I deflated the inner tube a spoke snapped! That can't be right, can it? It had no load on it whatsoever. It's a different spoke to the one that broke the first time, but still on the drive chain side. The wheel is a Specialized(?) Rival Fuser SL that came with the bike when I bought it a few months ago.

I weigh around 90kg so I'm not the lightest bloke but neither am I the largest, nor am I particularly powerful on the bike so it seems odd to me that the spokes could have broken due to use. I've read the sticky on wheels and it made me think that the spokes might have been over tensioned and the inflated inner tube was counter acting the excess tension, so when I fully deflated the tire the spoke couldn't take it any more.

Should I ask for the wheel to be fully rebuilt? Should I ask about a wheel with more spokes? Is this just something that happens with road bike wheels? As you can probably see I am pretty clueless when it comes to wheels so I would appreciate any advice before I take the wheel back to the LBS.


Spokes don't break from too much tension.

I googled the wheels to see what we're talking about. There are a number of reviews out there referring to rims cracking around the nipples which is a sign of too much tension, although there are also others referring to breaking spokes which is usually the sign of not enough tension. The gap between the too much and too little gets closer with fewer spokes and higher loads and can even overlap with wheels that are inappropriate for the purpose. (ie enough tension on the spokes will be too much for the rim)

The old fart in me would say that 24 spokes is not a lot but the rim is not super light or shallow so the wheel should be up to it. They are lightish and shallowish and so are favouring light weight (performance?) over reliability. I note that the Specialised website states a rider weight limit of 108kg which is still a good margin for a load & bike. (It also mentions a warranty if that is an option too)

If warranty isn't an option my first inclination would be to insert the new spoke, true the wheel, stress relieve the spokes and true it again if necessary. Factory wheels are rarely stress relieved, and many shop mechanics don't do it either. Do it yourself so you know it has been done right.

To stress relieve the spokes grab 2 neighbouring spokes half way along their length and try to squeeze them together hard, do this for all the spokes on both sides. You'll need to refer to 'The Bicycle Wheel' by Jobst Brandt for a detailed explanation of why this works.

If you still break spokes after that there is something else at play. Breaking spokes on the drive side is a little less common, it makes me wonder if the unusual flange design is contributing somehow. Where are the spokes breaking?

Cheers,

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Re: Broken spokes

Postby wizardhat » Tue Oct 23, 2012 4:05 pm

Thanks for the detailed reply, I'll try the stress relieving method when I get home tonight. Both spokes broke at the hub.
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Re: Broken spokes

Postby jacks1071 » Wed Oct 24, 2012 10:48 am

Ross wrote:Even if you buy a new set of wheels it's a good idea to check the tension of the spokes first rather than just chuck them on and ride of into the sunset.


If I bought a set of new wheels and had to re-tenstion them from brand new they'd be in the box heading back to the supplier.
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Re: Broken spokes

Postby rkelsen » Wed Oct 24, 2012 12:27 pm

My experience with cheap/machine built wheels is that they never seem to have enough tension from the factory.

One time I needed a wheel in a hurry, so bought the cheapest I could find. After riding it for approx. 20km, some of the spokes had loosened themselves to the point where you could wiggle them with your fingers. I had to flip the bike over and tension/true the wheel then and there, or it wouldn't have got me home. When I got home, I checked it and found that the dishing was wrong, so I took the opportunity to put a bit more tension into it. That was more than two years ago. It hasn't exploded yet, but then I don't use it every day.

And that wasn't the first wheel I've had this happen with.
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Re: Broken spokes

Postby barefoot » Wed Oct 24, 2012 3:42 pm

ironhanglider wrote:To stress relieve the spokes grab 2 neighbouring spokes half way along their length and try to squeeze them together hard, do this for all the spokes on both sides. You'll need to refer to 'The Bicycle Wheel' by Jobst Brandt for a detailed explanation of why this works.


That's a good method if you have strong enough hands.

I prefer the Sheldon Brown method, of jamming a lever (customarily an old LH crank arm) in to the cross-over of each spoke pair and bending them across each other. See sheldonbrown.com for details. If you do it right, the spokes should creak and sproing a bit as you do it... and that's the last you'll ever hear from them. Wheels should not creak and groan as you ride them "until they bed in", as some people accept they do.

Although I've never had one of Mr ProLite's wheelsets, I straight out don't trust wheels that somebody else has built. Whenever I've get a pre-built wheelset (as a wheelset or OEM on a new bike), the first thing I do is stress-relieve the spokes. If they're a decent quality wheel, they don't make a sound, they're as true afterwards as before, and they'll never give me any trouble. If they're lower quality... that's a different story. Often requires a bit of extra tension and some re-trueing. That's par for the course with cheap wheels, IMHO.

If I want a good wheel... I build it myself. Which routinely involves stress relieving.

The only wheels I've had fail on me have been the factory ones that I didn't get around to stress relieving before riding. Could be a coincidence... or not.

tim
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Re: Broken spokes

Postby jacks1071 » Wed Oct 24, 2012 11:46 pm

barefoot wrote:
Although I've never had one of Mr ProLite's wheelsets, I straight out don't trust wheels that somebody else has built. Whenever I've get a pre-built wheelset (as a wheelset or OEM on a new bike), the first thing I do is stress-relieve the spokes. If they're a decent quality wheel, they don't make a sound, they're as true afterwards as before, and they'll never give me any trouble. If they're lower quality... that's a different story. Often requires a bit of extra tension and some re-trueing. That's par for the course with cheap wheels, IMHO.

If I want a good wheel... I build it myself. Which routinely involves stress relieving.

The only wheels I've had fail on me have been the factory ones that I didn't get around to stress relieving before riding. Could be a coincidence... or not.

tim


Have a look at the video on how Pro-Lite wheels are built, you'll notice the machine that stress relieves the wheels towards the end of the video.

I can't speak for other brands but any wheel that needs stress relieving, truing, more spoke tension from brand new in this day and age. I'm sorry but you've bought a poorly built wheel, that is not normal for a quality product. If in your own garage you can build a wheel to the same quality and tollerances as a factory like Pro-Lite, then you are a skilled technician and I take my hat off to you :-)

http://www.youtube.com/watch?feature=pl ... cAWqNI0sV8
Last edited by jacks1071 on Thu Oct 25, 2012 9:32 am, edited 1 time in total.
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Re: Broken spokes

Postby wizardhat » Thu Oct 25, 2012 8:25 am

I stress releived the spokes and went for a 2hr ride this morning, no problems thus far! 8).
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