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Discussion Starter · #1 ·
when riding, every now and then, I hear and feel this loud metal clacking sound made by the chain, and I think it's because the teeth of the front chainrings (happens to both small and big rings) are stamping down right onto the chainlinks rather then between the links (where it should be doing). The sound is really loud and I can feel the metal clacking reverberating thru my fee.

This usually happens when the chain is in the upper half of the cassette (bigger cogs) and when I'm just rolling out from a complete stop, especially if the stop has a little bit of an incline where I'm forced to put some torque into the pedals. It never happens when I'm already moving along and spinning at over 80 rpm.

And this happens to a couple of my bikes, not just one.

So what could be causing this? Or is this something normal and acceptable? Chain is brand new. Chainrings are in good condition. This issue happens when I use Shimano chain or KMC chains. I have checked my crankset (Shimano) and bottom bracket (standard external English bb) and they both seem to be mounted properly with no play or give. The cassette is also properly mounted onto the wheel, and the wheel is properly mounted onto the bike. So every components along the drivetrain seems to be mounted as it should.

This issue doesn't happen enough to make me want pull my hair out, but it is very annoying, and i'm baffled why this is happening to 2 of my bikes.
 

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Do you observe your hypothesis? You've confirmed the chain isn't simply rubbing against the front derailleur? sometimes what you describe as far as chain and ring meshing happens in the rear. When it does i get the feeling of having almost no drive at all. Do you get this feeling?
 

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So when you say clankING do you mean a single clank now and then? As opposed to clank clank clank clank.......?

If you meant one single clank that's normal and acceptable. Or at least I've determined it is for me anyway. Clank clank clank isn't normal. I got no guess on the cause of that.
As for the single clank I've always thought that's caused by the rollers resting on top of the teeth then clanking down into proper position when you pedal but I'm not sure that's the case. I suppose it could be a similar thing going on inside the hub with the pawls.
 

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Discussion Starter · #4 ·
Do you observe your hypothesis? You've confirmed the chain isn't simply rubbing against the front derailleur? sometimes what you describe as far as chain and ring meshing happens in the rear. When it does i get the feeling of having almost no drive at all. Do you get this feeling?
chain is not rubbing the front derailleur.
I'm pretty sure it's coming from the front ring, not the rear cassette. And I have never gotten a feeling of no drive like you described.
Additionally, shifting at the front (and rear) is spot on, no issue.
 

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Discussion Starter · #5 ·
So when you say clankING do you mean a single clank now and then? As opposed to clank clank clank clank.......?

If you meant one single clank that's normal and acceptable. Or at least I've determined it is for me anyway. Clank clank clank isn't normal. I got no guess on the cause of that.
As for the single clank I've always thought that's caused by the rollers resting on top of the teeth then clanking down into proper position when you pedal but I'm not sure that's the case. I suppose it could be a similar thing going on inside the hub with the pawls.
yep just a single clank as the chain and chainring try to mesh up. Never a clank clank clank.

Interestingly, this happens to both my bikes using Dura Ace 7900. But on another bike with Dura Ace 7800, it doesn't happen. So maybe it has something to do with 7900 chainring design that is prone to this clanking during chain meshing? What groupset do you have?
 

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If it was only happening in the big cogs and big ring, I'd recommend checking the FD height to see if the chain is occasionally smacking the top of the cage. You say it happens in the small ring too though, so it's probably not that.
 

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I get this too. It happens intermittently when I start pedaling again after coasting. Happens on both of my shimano 11 speed bikes. It has never happened on my older 10 speed shimano bike. At first I thought maybe it was the pawls in the freehub not engaging right away. But since it happens on 2 different bikes(and 3 different rear wheels) I think it must be something in the drivetrain. It only happens maybe 1-3 times in a ride or sometimes not at all, and the only constant is it happens after coasting.
If someone has a fix I would love to hear it.
 

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yep just a single clank as the chain and chainring try to mesh up. Never a clank clank clank.

Interestingly, this happens to both my bikes using Dura Ace 7900. But on another bike with Dura Ace 7800, it doesn't happen. So maybe it has something to do with 7900 chainring design that is prone to this clanking during chain meshing? What groupset do you have?
I'm pretty sure it happens in the back. But not sure.

I don't really have any groupsets in this context because I use various replacement parts but I've had it happen on all sorts of combinations and on different bikes all together.
 

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chain is not rubbing the front derailleur.
I'm pretty sure it's coming from the front ring, not the rear cassette. And I have never gotten a feeling of no drive like you described.
Additionally, shifting at the front (and rear) is spot on, no issue.
IME this is a freehub issue - missed engagement in the freehub pawls. I have a hard time imagining how this happens in the chain rings though one possibility could be that either the rings are badly worn or the chain is badly worn and the chain has "ridden" on the top of the ring teeth and then drops in place. At a stretch, a stiff chain link or a badly lubricated chain could be issues, but I go back to the freehub as the most likely cause.
 

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Discussion Starter · #11 ·
I get this too. It happens intermittently when I start pedaling again after coasting. Happens on both of my shimano 11 speed bikes. It has never happened on my older 10 speed shimano bike. At first I thought maybe it was the pawls in the freehub not engaging right away. But since it happens on 2 different bikes(and 3 different rear wheels) I think it must be something in the drivetrain. It only happens maybe 1-3 times in a ride or sometimes not at all, and the only constant is it happens after coasting.
If someone has a fix I would love to hear it.
now that you mention coasting, I think I also get it while coasting/pedalling again too, but it is very rare, maybe 1-2 times. For me, when it happens, it's usually from a dead stop and I start to pedal. Furthermore, like you, this happens across multiple wheelses for me too (using Powertap G3 hub, Dura Ace 7900 hub).

Now that the others have chimed in, now I'm not sure if it's coming from the crank or the hub! That's how baffled I'm. But I do feel the strong reverberation thru my feet that's for sure.

Never happens while the bike is on the bike stand and I'm spinning the crank.
 

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Discussion Starter · #12 ·
If it was only happening in the big cogs and big ring, I'd recommend checking the FD height to see if the chain is occasionally smacking the top of the cage. You say it happens in the small ring too though, so it's probably not that.
pretty sure my chain is not smacking the top of the front derailleur, there is adequate clearance there
 

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now that you mention coasting, I think I also get it while coasting/pedalling again too, but it is very rare, maybe 1-2 times. For me, when it happens, it's usually from a dead stop and I start to pedal. Furthermore, like you, this happens across multiple wheelses for me too (using Powertap G3 hub, Dura Ace 7900 hub).

Now that the others have chimed in, now I'm not sure if it's coming from the crank or the hub! That's how baffled I'm. But I do feel the strong reverberation thru my feet that's for sure.

Never happens while the bike is on the bike stand and I'm spinning the crank.
I feel it in my feet also. And you definitely hear it when it happens. Feels exactly like the freehub pawls not engaging. But as I said happening on 2 different bikes with 3 different wheels I am almost positive it's not the freehubs. Maybe due to the narrower chain and tighter tolerances on 11 speed drivetrains? I can live with it but by no means does it feel "normal"
 

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Discussion Starter · #14 ·
IME this is a freehub issue - missed engagement in the freehub pawls. I have a hard time imagining how this happens in the chain rings though one possibility could be that either the rings are badly worn or the chain is badly worn and the chain has "ridden" on the top of the ring teeth and then drops in place. At a stretch, a stiff chain link or a badly lubricated chain could be issues, but I go back to the freehub as the most likely cause.
one one bike, the chain is new, and chainrings are in prototypical worn down shape for rings that are 3-5k miles, i'm a lightweight guy and regularly rotate my riding between 3-4 bikes, so I think my chainrings are good.

My "theory" as to why this issue is happening is that as the teeth of the chainrings try to mesh with the chain, some teeth will (randomly) fail to fall betweeen the rollers and instead hit the side-plates of the links dead on before the teeth will fall in between the rollers. This could happen if the chainline is a little crooked, hence, why my original quesiton "is my chainline properly aligned". But if every component along the drivetrain is properly installed, then there isn't much I can do to fix the chainline angle, and without possibly introducing other new issues!

I thought about rear hub too, but then this happens across 2-3 wheelset, one using a Powertap G3 hub (Novatec 3-pawl hub), one using a Dura Ace 7900 hub, one using a Bontrager TLR wheelset (Novatec 3-pawl hub). I also have a wheelset that use DT240 rear hub, which uses the DT Swiss ring design and not traditional pawls, and I haven't paid attention if this issue also happens to the wheel with DT240 hub or not.

But let's assume it's happening at the hub, what does this say about my hubs then? Are they worn out already? and if so, I should expect this issue to get progressively worse to these hubs? Or is this a random event? And if it's random, then I should other people with the similar 3-pawl design hub to experience this too right? I believe the the Novatec 3-pawl hub is used in a lot of OEM wheelsets too, so I should see a lot of others experiencing this issue too?

I cannot say with 100% if issue is coming from the crank or the hub though. I'm baffled. But i'm hoping that I'll get enough people to chime in here so I can get to the bottom of this, maybe there's no solution, but at least I'm aware where/why the issue is coming from.
 

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Discussion Starter · #15 ·
guys,

another question, if this is happening at the freehub, and that the pawls are no engaging, then if I take a at the pawls in these freehubs, then should I expect to see that these pawls, or those little groves that the pawls bite into, to see them wearing down with bite marks or slippage marks? I mean, should I see any abnormal signs that the pawls are slipping inside the hubs? I can look for those sign. As I recall, though, recently when I greased all these freehubs I did not find any sign of excessive wear of these pawls. But then agian, I probably didn't know what I was supposed to be looking for.
 

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Discussion Starter · #16 ·
I feel it in my feet also. And you definitely hear it when it happens. Feels exactly like the freehub pawls not engaging. But as I said happening on 2 different bikes with 3 different wheels I am almost positive it's not the freehubs. Maybe due to the narrower chain and tighter tolerances on 11 speed drivetrains? I can live with it but by no means does it feel "normal"
This happens on my Dura Ace 7900 systems, so it's 10 speed for me.
What's your groupset? some Shimano 11 speed group?

I looked at the width difference between the 10speed and 11speed chain, and the outter width is barely noticeable (with the 11 speed chain a tad narrower, barely noticeable), but the inner width between the side-plates appears to be the same. I didn't use a caliper, just using my eyeballs! So...
 

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This happens on my Dura Ace 7900 systems, so it's 10 speed for me.
What's your groupset? some Shimano 11 speed group?

I looked at the width difference between the 10speed and 11speed chain, and the outter width is barely noticeable (with the 11 speed chain a tad narrower, barely noticeable), but the inner width between the side-plates appears to be the same. I didn't use a caliper, just using my eyeballs! So...
Mine are Ultegra 11 speed 6800. Yours is 10 speed? So maybe it is freehub design issue? I have a Rol Racing wheel(3 pawl) Giant Carbon wheels(3 pawl) and a Hed wheel with Hed hub (5 pawl). Oh and also a Bontrager wheel (oem from Domane) I think it is a formula hub. It happens to all of them. Wish I had a DT Swiss with star ratchet to try.
 

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Another possibility is chain suck, where the chain momentarily does not unwrap from the bottom of the front chain ring, then lets go.
In bad cases this can also happen while shifting in front big to small, and the chain comes up and scratches the side of the chain stay. Google it.
 

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Since you greased the pawls my guess is that you used grease that is too heavy/thick and it's sticking the pawls momentarily. Try lighter grease or a heavy oil like DuMonde freehub oil.
 

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Since you greased the pawls my guess is that you used grease that is too heavy/thick and it's sticking the pawls momentarily. Try lighter grease or a heavy oil like DuMonde freehub oil.
I've had this happen on 4 different hubs (2 dura ace, alchemy and royce) at various stages of being greased. I really doubt that's it and think it's the chain resting on top of a gear then slamming down into position when you pedal.

Regardless of what it is, I had it happen the first time about 50,000 miles ago and haven't had any problems so I wouldn't worry about it.
 
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