# Mysterious Knocking Sound?



## Wood Devil (Apr 30, 2011)

Alright ... here's the deal:

The bike is new; I just picked it up May 3rd. It's a 2010 Cannondale CAAD9 5 105. In the week or so that I have had it, I've been out on five rides totaling 350 miles. 

The first couple rides had been plagued by shifting problems, and a creaking sound I figured to be the handlebars. 

Then an aggravating knocking sound started. I couldn't figure out where it was coming from, be it the cranks, the seat post, the saddle, the frame or peddles (Look Keo Classic). I just wasn't sure. So I brought the bike back to the shop and had them do a complete inspection on the thing, because during that ride I noticed that several bolts (like the one holding the crank on) were loose.

So I get the bike back the next day. They took out the BB30 and re-greased, threw back in. Yesterday I took her out for a good ride -- 70 miles. The shifting was better, and no noticeable knocking sounds.

Today, I went out again -- another 70 miles. Shifting in the low gears was starting to get noisy again, and during a break I crouched down and noticed the rear derailleur was slightly off. No big deal. I adjusted it, and shifting has been good to go since. But after 30 miles or so, I began to start hearing the strange knocking sound again.

It was infrequent, at first noticed in only in the easy gears when I was out of the saddle and heading up hills. 

As the ride progressed, the knocking became more frequent. Again, most noticeable when I was out of the saddle working my way up hills. On the final half mile before I got to my house, I was standing up, and started to hop a bid on the pedals in an attempt to try and locate the knocking, and each time my weight came down, I heard the knocking sound.

Could it be the cranks? The bottom bracket? The pedals? A frame issue? What?

Have there been any issues with FSA cranks, or the BB30 I should be aware of? I know they had a recall on the BB30, but my shop claims there were aware of that, and the BB on my bike is good to go.

Any help would be greatly appreciated.


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## testpilot (Aug 20, 2010)

Loose cassette?


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## Optimus (Jun 18, 2010)

What's the serial # on your crank arm? It should start with a 10 followed by b, c or d.


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## Wood Devil (Apr 30, 2011)

Optimus said:


> What's the serial # on your crank arm? It should start with a 10 followed by b, c or d.


There's a large number stamped in the middle of the crank arm, which read: CK-OSC6021 G

Then a small set of numbers in white print up near the top, where the peddle is, which read: 10L33792


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## Guest (May 15, 2011)

Try putting some grease on the part of your seatpost that is inserted in the seatpost tube. Don't use the grease on a carbon fiber seatpost though, you'll need some carbon paste for that.


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## wim (Feb 28, 2005)

*One distinct possibility.*

I said this before when responding to posts like yours, but it's always been met with disbelief. Regardless, I'm going to say it again. What you describe are the classical symptoms of pedaling squares. Pedaling squares means letting the upper run of the chain go slack at top and bottom dead center of the crank, then snapping it back into tension. That snap produces the "mysterious knocking sound." As you get tired, you pedal squares more and more. In you own words, "as the ride progressed, the knocking became more frequent."


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## Wood Devil (Apr 30, 2011)

Mevadus said:


> Try putting some grease on the part of your seatpost that is inserted in the seatpost tube. Don't use the grease on a carbon fiber seatpost though, you'll need some carbon paste for that.


Yes, it's a Cannondale C3 "Carbon Wrapped". So now I need to go out and buy this ... carbon paste?


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## Wood Devil (Apr 30, 2011)

wim said:


> I said this before when responding to posts like yours, but it's always been met with disbelief. Regardless, I'm going to say it again. What you describe are the classical symptoms of pedaling squares. Pedaling squares means letting the upper run of the chain go slack at top and bottom dead center of the crank, then snapping it back into tension. That snap produces the "mysterious knocking sound." As you get tired, you pedal squares more and more. In you own words, "as the ride progressed, the knocking became more frequent."


No, I'm nearly certain this is not it. I've experienced what your talking about; this is more of a subtle knocking sound as pressure is applied on the downward stroke of (primarily noted) the right crank arm. Like all other mystery sounds, it could just as likely be coming from another place entirely.


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## wim (Feb 28, 2005)

Wood Devil said:


> this is more of a subtle knocking sound as pressure is applied on the downward stroke of (primarily noted) the right crank arm.


Agree, it's not what I thought then. The chain-snap knock is not subtle—loud and clear.


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## Guest (May 15, 2011)

Wood Devil said:


> Yes, it's a Cannondale C3 "Carbon Wrapped". So now I need to go out and buy this ... carbon paste?


By no means am I suggesting that this is your exact problem, however I can tell you that I had a very similar problem and it took me a while to figure out where it was coming from. I ended up pulling my seattube out and greasing it because I hadn't done that when I first installed it. It solved my knocking sound, and the whole time I thought it was in my drivetrain somewhere. 

The carbon paste isn't too expensive, maybe $10 - $20 max, and if it doesn't solve your problem it wouldn't be like you spent hundreds of dollars trying to figure it out. Its an idea that I would try... Heck, your LBS might even do it for you. If you pull your seatpost out now, is there paste on it? If not, there should be. I guess that would be a quick check to make sure its not there already.


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## Wood Devil (Apr 30, 2011)

Mevadus said:


> By no means am I suggesting that this is your exact problem, however I can tell you that I had a very similar problem and it took me a while to figure out where it was coming from. I ended up pulling my seattube out and greasing it because I hadn't done that when I first installed it. It solved my knocking sound, and the whole time I thought it was in my drivetrain somewhere.
> 
> The carbon paste isn't too expensive, maybe $10 - $20 max, and if it doesn't solve your problem it wouldn't be like you spent hundreds of dollars trying to figure it out. Its an idea that I would try... Heck, your LBS might even do it for you. If you pull your seatpost out now, is there paste on it? If not, there should be. I guess that would be a quick check to make sure its not there already.


Yup, it's greased ... or pasted. Not sure which. I'll probably grab some of the paste, anyway (if I can find it), and slap some on. But then again, should I be doing that even if the carbon is covered by a clear coat? I'm not sure if the regular grease I've used on my mountain bike's post would suffice.


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## Guest (May 16, 2011)

Don't use grease on a clear-coated carbon post. Just use carbon paste. My Giant TCR's seatpost is also clearcoat carbon, and it has carbon paste on it. My guess, since it is pasted, is that this is not your problem. Sorry...


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## onespeedbiker (May 28, 2007)

Might be loose pedals, see that they're tight. Also, grab your crankarms and see if they're is any movement laterally at the bottom bracket. Another way to check a bottom bracket is to put the front wheel against a wall, place the crankarm at 3:00 and put your weight on the pedal with a bouncing motion. This should produce the knock if it's in the crank/bottom bracket somewhere


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## the sarge (Jan 10, 2011)

i had a very similar issue with my bike at about the same mileage. ended up replacing the bb30 bearings after repacking them once and its now gone. lbs said that the factory likely over torqued the bb causing damage to the bearings.

the shifting should smooth out soon everything will go out of adjustment repeatedly for the first few hundred miles as it breaks in


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## Kontact (Apr 1, 2011)

It sounds like a shoddy build, if you had crank bolts and other essential things loose. So that's not helping.

Is the knock once per revolution, twice (both pedals), 3 or so times (chain), or more frequent? Does it happen in certain gears? In the saddle, out of the saddle? Does your foot hit the chainstays or crank? Is the cassette tight on the hub? Is it the wheel flexing into the brake pads when climbing?

More info needed.


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## spookyload (Jan 30, 2004)

What wheels are on the bike?


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## Wood Devil (Apr 30, 2011)

onespeedbiker said:


> Might be loose pedals, see that they're tight. Also, grab your crankarms and see if they're is any movement laterally at the bottom bracket. Another way to check a bottom bracket is to put the front wheel against a wall, place the crankarm at 3:00 and put your weight on the pedal with a bouncing motion. This should produce the knock if it's in the crank/bottom bracket somewhere


Yes! That's exactly what I did! 

At the end of my last ride I did that. With each hop, there emitted a knocking sound. But oddly, doing it again last night (in my regular shoes, no the Diadoras), oddly, I couldn't replicate it. It was quiet? This just adds to my confusion?

It's almost like the bike needs to be warmed up to start making the noises.


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## Kontact (Apr 1, 2011)

Wood Devil said:


> Yes! That's exactly what I did!
> 
> At the end of my last ride I did that. With each hop, there emitted a knocking sound. But oddly, doing it again last night (in my regular shoes, no the Diadoras), oddly, I couldn't replicate it. It was quiet? This just adds to my confusion?
> 
> It's almost like the bike needs to be warmed up to start making the noises.


Or the sound is coming from your shoes, like a steel plate sliding around, or the cleat not being tight.


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## powhatan (Feb 16, 2003)

Your Caaad 9 has been nothing but a dissapointment!


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## 45K10 (May 1, 2008)

I think more than likely it is your Bottom Bracket. When you took apart the bottom bracket did the bearings slip out or did you have to press them out? 

BB-30 is suppose to be a "press-fit" and not a "slip-fit" I have had the same issue with my Tarmac BB-30. According to the new specialized crank installation manual the bearings are to be installed utilizing Loctite 609 on the outer race of the bearing and the BB shell itself. After following the new installation procedure the noise disappeared.

I think the massed produce bikes equipped with BB-30 shells have machining tolerance problems and do not meet the press-fit specifications. The Loctite 609 hardens and makes up the gaps in between the bearing race and the BB shell.

I would suggest a new set of bearings and install them with the loctite and let it set for 12 hours before you ride it.


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## Wood Devil (Apr 30, 2011)

Kontact said:


> Or the sound is coming from your shoes, like a steel plate sliding around, or the cleat not being tight.


I'm hoping that is the case. To rule it out, I tightened each bolt. Most were tight and didn't have much if any more to turn. The right shoe did have one that turned a bit more. But I'll have to wait another couple weeks for the weather to clear, as rain is forecast here for pretty much every day for the remainder of May. When I can get back on my bike, I'll have to test it out.


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## Wood Devil (Apr 30, 2011)

45K10 said:


> I think more than likely it is your Bottom Bracket. When you took apart the bottom bracket did the bearings slip out or did you have to press them out?
> 
> BB-30 is suppose to be a "press-fit" and not a "slip-fit" I have had the same issue with my Tarmac BB-30. According to the new specialized crank installation manual the bearings are to be installed utilizing Loctite 609 on the outer race of the bearing and the BB shell itself. After following the new installation procedure the noise disappeared.
> 
> ...


I didn't take the bearings out myself -- the shop did. I don't have the required tools. And now not being able to entirely trust the bike shop to be able to figure this thing out, I'm at a loss as to what to do.

Unless someone knows of a specific shop in Massachusetts that has a really good and trusted bike tech ... ?


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## jrz1 (Mar 15, 2006)

+1 on the cassette tightening. My bike made a similiar sound and I was absolutely convinced it was my bottom bracket. Fortunately I have a great mechanic and he suggested that I first check that my cassette is on tight. Sure enough when I tightened it up some the knocking stopped!!


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## ukbloke (Sep 1, 2007)

Have you checked for a loose head-set? Stand over the bike, apply front brake and rock the front of the bike forwards and backwards looking for play between the fork (steerer) and the frame.


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## Wood Devil (Apr 30, 2011)

ukbloke said:


> Have you checked for a loose head-set? Stand over the bike, apply front brake and rock the front of the bike forwards and backwards looking for play between the fork (steerer) and the frame.


Dude, I think you might have figured this damn thing out!

I press down on the bars and ... KNOCKING!

There are what look like carbon spacers beneath the C2 stem. They are not stacked very neatly. The main screw inside the stem was not very tight. But I'm not sure how to proceed from here; I don't want to over tighten and do damage. I did tighten it a bit, but it still knocks when pressure is applied to the bars.

Hmm ...


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## ukbloke (Sep 1, 2007)

This is not how to tighten it, and that will not fix it in any way. I could explain, but your best course of action is to take it to the LBS and tell them that your head-set is loose and demonstrate the knocking to them. I would also demand that their chief mechanic works on the bike, and also gives the whole bike a once-over to look for other issues. They should have checked this during the initial bike build. Unless they make amends, I'd also be looking for a new bike shop to maintain the bike (or do it yourself if you are inclined to learn).


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## Wood Devil (Apr 30, 2011)

ukbloke said:


> This is not how to tighten it, and that will not fix it in any way. I could explain, but your best course of action is to take it to the LBS and tell them that your head-set is loose and demonstrate the knocking to them. I would also demand that their chief mechanic works on the bike, and also gives the whole bike a once-over to look for other issues. They should have checked this during the initial bike build. Unless they make amends, I'd also be looking for a new bike shop to maintain the bike (or do it yourself if you are inclined to learn).


Yes, I'm not too happy at all with these guys. I've been going to them since I bought my first Trek back in 97. And to spend $1200 on a bike and be having to deal with this aggravation ... ? It pisses me off.

That said, I have learned to do most of my own work on my mountain bike, with the exception of the trickier jobs that require more special tools (like this probably headset issue). So, I guess I'll be grabbing that Zinn Road Bike book and learn to work on the CAAD, too.


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## ukbloke (Sep 1, 2007)

Actually adjusting the head-set doesn't need special tools, just some knowledge and care. Ideally one would use a torque wrench for the stem bolts, but you can do it by judgement too. The bolt you are adjusting is the pre-load - it is actually the stem that holds the head-set in place once the pre-load is set correctly. If you are interested in doing it yourself follow the advice on the Park Tool web-site - see "Headset Adjustment - Threadless Type".


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## Trout (Mar 27, 2007)

One other thought, it isn't an adjustable stem is it?

Roommate was having the same complaint and when I looked at it after a bit figured out in her case it was the adjustable stem torqueing during climbing and causing that popping noise.


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## Wood Devil (Apr 30, 2011)

Trout said:


> One other thought, it isn't an adjustable stem is it?
> 
> Roommate was having the same complaint and when I looked at it after a bit figured out in her case it was the adjustable stem torqueing during climbing and causing that popping noise.


Not sure. It's a Cannondale C2. There are carbon spacers between the stem and and headset.


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## spookyload (Jan 30, 2004)

Wood Devil said:


> Yes, I'm not too happy at all with these guys. I've been going to them since I bought my first Trek back in 97. And to spend $1200 on a bike and be having to deal with this aggravation ... ? It pisses me off.
> 
> That said, I have learned to do most of my own work on my mountain bike, with the exception of the trickier jobs that require more special tools (like this probably headset issue). So, I guess I'll be grabbing that Zinn Road Bike book and learn to work on the CAAD, too.


Just go to park tools website. They have instructions on how to do just about everything. Better than Zinn's book as it stay current with new equipment since it isn't in print, and it is free online.


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## spookyload (Jan 30, 2004)

Wood Devil said:


> Not sure. It's a Cannondale C2. There are carbon spacers between the stem and and headset.


If the Headset is tightented and the bike still makes a clunking noise, don't rule out a heattube in the frame that isn't milled to spec. Just because the bearings fit in the headtube doesn't mean that it is to spec. If they are moving around in the slightest becuase the headtube is out of spec, you will get clunking even if the bearings are adjusted properly. I worked on an old MTB with a headshock at the shop for a while till I finally figured this puzzle out. It was a new bike that a customer was complaining about. We ended up getting a warranty frame for him. Hopefully the headset is just loose.


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## Trout (Mar 27, 2007)

Wood Devil said:


> Not sure. It's a Cannondale C2. There are carbon spacers between the stem and and headset.


an adjustable stem is one that have a pivot point in it, so you can change the angle. I going to guess from you answer that that's a no. If it is and adjustable stem you'd see a bolt an pivot point to adjust the angle just beyond the end of the fork. 

If not, basic integrated adjustments (aluminum fork steering tube w a star nut installed): loosen the bolt holding the stem onto the fork, hand weight everything onto the wheel to make sure the bearings are set properly, align stem and wheel, then tighten the Headset bolt (hand tightened, shouldn't have to strain to tighten it.) Wiggle hangle bars to see if they are set, then retighten stem bolts. 

If your fork steerer is carbon, the only thing I find works is weighting the stem with downward pressure and tighening the stem bolts. (a little more tricky but you should be able the tell if its set properly before the ride by pulling up and down on the handlebars.)


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## zninedi (Jan 17, 2011)

The wheels... Had the same problem with my caad9... Put some grease where the fork have contact with the wheelaxel, do it on both the front and rear wheel.. My lbs said that this happens alot with cannondale and mavoc wheels..

Sorry for my eng


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