# Clunking from rear cassette under load



## jamesdwebber (May 17, 2013)

Hi all,

I have an older (2000?) Trek 520 with a 9 speed drivetrain. When I am really torquing on the pedals on steep climbs, I hear a clunk or rattle with each pedal stroke. My first thought was to check the BB, so yesterday I took out the crankset and inspected the bottom bracket (an Octalink v2). The BB turns fine, so I cleaned and re-greased everything (BB threads, cup threads, splines of BB) before reinstalling and torquing things down. 

I'm still hearing the noise, and I'm thinking it may be the cassette moving on the Shimano freehub. Tomorrow I'm going to try to remove the cassette, clean the hub, and put a little fresh grease on the freehub splines. Can you think of anything else to check? I cleaned, greased, and tightened the pedal axles, the chainring bolts, and the seatpost. I assume the freehub needs no spacer with a 9 speed Shimano cassette, but is there a possibility that I might get rid of this clunk by putting a 1mm spacer behind the cassette?

Thanks in advance!


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## MMsRepBike (Apr 1, 2014)




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## jamesdwebber (May 17, 2013)

Nice chart, MMsRepBike! As I look at it, I realize that I'm talking about a noise that happens with every pedal rotation, both when standing or sitting. The clunking is loudest when I'm applying the most force through the pedals. Since I've just checked the BB/crank area, I'm guessing cassette is the issue.

I went ahead and removed the cassette tonight. Wiped off freehub body, applied a little grease to the splines and to the lockring threads, and then reinstalled the cassette. Torqued it down fully but there is still a little bit of side-to-side play in the cassette. I'm wondering, should I try putting a 1 mm spacer behind the cassette? Or should I not worry about the play in the cassette as a potential culprit for my noise?


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## ibericb (Oct 28, 2014)

This may help you pinpoint the cause.


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## DaveG (Feb 4, 2004)

jamesdwebber said:


> Hi all,
> 
> I have an older (2000?) Trek 520 with a 9 speed drivetrain. When I am really torquing on the pedals on steep climbs, I hear a clunk or rattle with each pedal stroke. My first thought was to check the BB, so yesterday I took out the crankset and inspected the bottom bracket (an Octalink v2). The BB turns fine, so I cleaned and re-greased everything (BB threads, cup threads, splines of BB) before reinstalling and torquing things down.
> 
> ...


Have you ruled out chain skip?


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## jamesdwebber (May 17, 2013)

ibericb said:


> This may help you pinpoint the cause.


Wow. This page will keep me busy for a while. I hadn't been thinking about the chain skipping since the chain and cassette are less than 6 months old. But I'll take a look. Meanwhile, any more suggestions on what I should check first from the list above?

Thanks again, all.


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## ibericb (Oct 28, 2014)

Note that near the top of the page cited is lateral cassette movement on the freehub. If you have lateral play you can move with your fingers after the locknut is tightened, then something probably isn't right.


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## jamesdwebber (May 17, 2013)

ibericb said:


> Note that near the top of the page cited is lateral cassette movement on the freehub. If you have lateral play you can move with your fingers after the locknut is tightened, then something probably isn't right.


Good point. I've tightened the cassette lockring using this:

Park Tool Co. » SR-11 : 5 to 11-Speed Compatible Chain Whip/Sprocket Remover : Freewheel & Cassette

I tightened the lockring down hard using the full leverage of the tool, but there's still a little bit of play if I push the cassette inward toward the hub or outward away from the hub. Time to try a spacer behind the cassette?


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## ibericb (Oct 28, 2014)

jamesdwebber said:


> Good point. I've tightened the cassette lockring using this:
> 
> Park Tool Co. » SR-11 : 5 to 11-Speed Compatible Chain Whip/Sprocket Remover : Freewheel & Cassette
> 
> I tightened the lockring down hard using the full leverage of the tool, but there's still a little bit of play if I push the cassette inward toward the hub or outward away from the hub. Time to try a spacer behind the cassette?


Is there supposed to be a spacer behind that 9-speed cassette on that freehub?


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## MMsRepBike (Apr 1, 2014)

There should be no play. And you should be using a torque wrench to tighten on a cassette. It's fairly easy to destroy that lock ring washer without one.

I use a Craftsman torque wrench that I bought for my automobile work. It has settings for both newton meters and pound feet. I use a lockring tool from Icetoolz. It has a square hole in the back I can just mate the torque wrench to. I use it on pedals as well.

So if there is any play, yes, there should be a spacer behind the cassette. Once torqued properly the cassette should be tight on there, no shimmy or sliding at all.


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## jamesdwebber (May 17, 2013)

Thanks--gonna give that a try. And I think I will finally get a torque wrench...


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## MMsRepBike (Apr 1, 2014)

Keep in mind that I have and use two different torque wrenches as I strongly recommend most do.

One for all of the small stuff. This one is newton meter specific and runs from about 3-15 newton meters only. I use the Park Tool one, I think it's the TW-5.

One for all of the big stuff. Park Tool makes I think the TW-6 for this. A large wrench that will handle stuff like bottom brackets, cassettes and pedals, stuff in the 40ish newton meter range. 

I think both are equally important to have. One doubles for use on cars and stuff too


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## ibericb (Oct 28, 2014)

This might help you figure out if you need a spacer. You said 9-speed, and mentioned Shimano. You also need to know the freehub make and design.


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## jamesdwebber (May 17, 2013)

Great--thanks! So I have a Shimano 9/10 freehub, and according to the chart, I shouldn't need a spacer with a Shimano 9 spd cassette. But given the amount of play I have in the cassette, I think I need one. I put one spacer behind the cassette, and it cut the play considerably. It's not gone, but it's a lot smaller, and based on a quick spin down my street, the clunking is not as loud. I tried to fit two 1mm spacers behind the cassette, but then the lockring wouldn't thread on. 

I'll do a ride tomorrow to see how it works. If the noise persists, I'll try to get some .5mm spacers to see if they fit.


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## paul.harris.948 (Apr 21, 2015)

Noted all the focus in the back. What about the front Der.? I had a Giant that would flex a lot.
Depending on the gear I was in, if the chain was close to the cage it would rub under heavy pedal pressure each rotation as I applied the power on the right side down stroke. This is something you can see while riding.


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## jamesdwebber (May 17, 2013)

paul.harris.948 said:


> Noted all the focus in the back. What about the front Der.? I had a Giant that would flex a lot.
> Depending on the gear I was in, if the chain was close to the cage it would rub under heavy pedal pressure each rotation as I applied the power on the right side down stroke. This is something you can see while riding.


I'll have to check that out too. Update: I rode with the 1mm spacer behind the cassette, and the noise from the cassette is hardly there. Now my rear derailleur is a bit off since I'd adjusted it to the cassette's old position. I'll re-adjust and see where I stand. Thanks to everyone for the tips.


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