clicking / cracking wheel

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clicking / cracking wheel

Postby brit_in_oz » Tue Jul 17, 2012 8:57 pm

Got a question for you wheel builders. I have some shimano RS80's (carbon laminate clincher with alloy braking surface). Recently i have developed a clicking noise. It's intermittent, could be a couple of times a second or once every kilometer. Its not a squeak or creak, its a definate click / crack sound. I have taken off the tyre etc and checked everything closly, no cracks or issues with the rim or spokes that i can see (and being a materials engineer I can normally spot a defect in an item pretty easily).

A experienced colleague at work thinks it may be due to the spoke tension, in that if its too loose its allowing the wheel to deform at certain positional loadings which is why the noise is intermittent depending on the angle the wheel is at relative to the load. The wheels itself doesnt seem to be significantly out of true, though i dont have a truing stand to check but brakes are fairly close and little rubbing. FWIW the wheel is the front one thats radially laced with no crossing spokes. Other than that I am banging my head against a wall..so any help much appreciated.

I know its the wheel as soon as I change to any others i have no problems or noises.
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by BNA » Tue Jul 17, 2012 11:02 pm

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Re: clicking / cracking wheel

Postby jacks1071 » Tue Jul 17, 2012 11:02 pm

If the spoke tension feels even and alright and you can't spot any cracks in the rims and hubs.

Try and put a drop of oil where each spoke meets the hub, put a drop of oil into each nipple, and put a drop of oil onto each spoke cross (where the spokes rub on each other) see if that fixes it.

On some wheels the spoke cross is so tight that sometimes you get a twang sort of noise out of them and its just from friction of the two spokes rubbing on each other and it can be a bit of a concern until you are sure whats causing the noise..

If its still making the noise after you've oiled everything I'd go looking for cracks again.
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Re: clicking / cracking wheel

Postby rkelsen » Wed Jul 18, 2012 9:52 am

Spoke tension would be the first thing I'd check too. Maybe there's one spoke slightly looser than the others.

What tyre pressures are you running?
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Re: clicking / cracking wheel

Postby ironhanglider » Wed Jul 18, 2012 3:45 pm

Does it happen more often with side loads such as cornering or when out of the saddle?

Have you replaced a tyre/tube recently?

I'll suggest a valve stem shifting within the hole. Sometimes this is so bad as to be every revolution, other times it only happens under unusual loads. 4cm of insulating tape is at least a cheap and easy test. Stab the valve through the tape at the middle and stick the tape to the rim making sure it doesn't go over the brake track. Many people put heat shrink tubing over valves before installing them to prevent this.

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Re: clicking / cracking wheel

Postby wombatK » Wed Jul 18, 2012 8:45 pm

Being a materials engineer, it ought to be easy to spot cracks that propagate from surface defects - like most metals do.

But doesn't carbon fibre cracking propagate from the inside - the opposite of metals ? So it's hard to detect them before
they completely let go. Might be worth trying to load up the wheel in a more controlled environment (e.g. on trainer/rollers)
and getting someone to check more closely for the source of the noise.
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Re: clicking / cracking wheel

Postby juanacity » Sun Aug 05, 2012 8:32 am

Hello,

Just registered to give you my experience with this same exact problem since I finally got it solved and it was driving me crazy.

I have a relatively new set of Shimano RS80 C24 wheels with less than 500 km on them. A little bit ago I noticed an intermittent "clicking" noise coming from them that then became constant (ie once every wheel revolution). I isolated the noise to my rear wheel and one particular spoke bed. I could get it to click even if I just rolled the wheel with my hands on the ground while applying weight whenever the load was on one particular spoke. It wasn't obvious to me just by feeling the spoke tension with my hand that it was loose. However, I put it on my truing stand, and sure enough, the clicking spoke was clearly loose and the wheel slightly out of true right there. I quickly tightened it, but it had no effect when I checked for the click. So I added a drop of oil, put it back on the truing stand and after two more attempts (and to my feel being over tensioned but still true) I was able to get it to become silent.

I really want to like these wheels since I got them cheap and they feel nice and light when riding, but I've been disappointed with a few things so far; clicking, going slightly out of true (both wheels), poor braking, they don't feel smooth when spun in hand, and they have a substantial "divot" in their roundness right where the seam of the aluminum rim is. Hopefully they stay true now and the other issues are insignificant/resolve eventually.

Best of luck getting this sorted.
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Re: clicking / cracking wheel

Postby Reman » Sun Aug 05, 2012 9:51 pm

juanacity wrote:It wasn't obvious to me just by feeling the spoke tension with my hand that it was loose. However, I put it on my truing stand, and sure enough, the clicking spoke was clearly loose and the wheel slightly out of true right there. I quickly tightened it, but it had no effect when I checked for the click. So I added a drop of oil, put it back on the truing stand and after two more attempts (and to my feel being over tensioned but still true) I was able to get it to become silent.


Fastest way to check for a loose spoke is to go around and "pluck" each spoke like a guitar string. They should have a similar tone, the tone a loose spoke makes will stand out like the dogs proverbials!

Other options are that the spoke heads aren't bedded in the hub properly or the nipples aren't seated in the rim properly.

I can guarantee that visual inspection will almost tell you nothing about a wheel, whereas the tone of plucked spokes can tell you an interesting story....
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Re: clicking / cracking wheel

Postby LarryLong » Sun Aug 05, 2012 10:11 pm

I'm having the same problem on an older bike, so I'm going to try some of the tips in this thread. I asked the guy in my local bike shop and he actually thought it was the head stem clicking a little bit and nothing to worry about. I'm still not convinced.
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