SethB

I have no idea what it is, my biggest guess is the rear derailleur. It only happens over bumps. The weird thing is when I go and grab the RDR, it is solid as a mountain..... I need some help in what to do/check to narrow this down. It is highly annoying and I just don't think it should be doing that

tFUnK

Cables tapping against the frame?

grayEZrider

I have the same problem with a wide-range gearing setup. It will reduce it if you can shorten the chain a link.

veganbikes

Always check QR or thru axle tightness, bolt tightness and for anything loose that could make noise.

ridelikeaturtle

Check for any side-to-side movement in the rear wheel? Maybe the bearings need adjustment.

bpcyclist

Tragically, it is a very long list, indeed. I have learned over the years that I am exceptionally not good at correctly guessing where the sound is emanating from. One of my favorite examples of this was the time I was absolutely certain I had some kind of front end/hub clicking occurring. Just positive. It turned out to be coming from the right side of my helmet lining!!!

Darth Lefty 

A few months ago I had a growly sound from the rear. I took the hub all apart, found a gruesome pit in the cone, started threads here and MTBR about it, figured out what to buy, put it all back and still grglrglr. I finally stopped it... when I removed the reflectior. Alas the shame.

SethB

Im internally routed back there.. so I don't think so. I wish it were that simple ha!
So its not chainslap, I have a clutch on the RDR, and when the noise happens I can watch the chain and it definitely isn't getting near the frame.
I did have a little wobble but I fixed that. I was so hoping this was the cause of my noise, but alas it wasn't
Oof, long list = never ending list lol. So funny that it was your helmet xD I will have to keep looking I guess. Maybe I'll try to rig up a camera to watch everything back there as I drive. I don't have any GoPros, just my phone and a mount tho

delbiker1 

Internally routed cables have been known to make rattling type noise. I have a CF framed bike with internal routing and I am pretty sure that is the source of some rattling sounds that I get at times, especially bumps.

curbtender

Remove your seatpost and turn the bike upside down. You might have something that got in there that you can shake out.

sch

Years ago I had a rattle from a not fully torqued cassette lock ring. If you tighten cassettes by hand you will be
surprised by how much more torque is needed when you measure with a torque wrench. My bike with a
Di2 internal wiring has a clank on bumps from the junction connector inside the down tube despite 5 centering
clips. Finding noise sources on a singleton is annoying enough, but wait til you try it on a tandem.

SethB

So I had an idea... I went for a ride just now and when I started to hear the rattle I put the heal of my foot onto the derailleur and I still heard the rattle... My idea said to myself "If I put force on the RDR, it should stop it from rattling right?" So that should eliminate the RDR as the culprit right?

I may just go ahead and put my other RDR on to completely eliminate it tho. Otherwise it will be time to take apart the free hub body and inspect everything.

SethB

I will take a look at the cables and see if anything feels loose.
Hmm. I will give it a try. It is a FS MTB. The rattle definitely seems to come from the back. But hey im down for trying anything, it is so annoying lol
Oh hey.. I did have the cogs off not too long ago... Maybe I didn't tighten them enough. I will take a look!

UKFan4Sure

loose cassette. tighten the locknut

SethB

Yep. I really cranked down on it with the breaker bar... I think it may be too tight and be a pain to get off....... But I do think the cassette or free hub is shot. Here's a vid as to why I think that. Either that or I am missing a spacer, but I don't think the pressure from the other cogs is what keeps them still.

EDIT: The rattle seems to have gone away, maybe cranking on it did the trick. Will definitely have a hard time getting it off though. Will need to extend the chain whip handle to give me more leverage

SethB

Rattle is still there.. anyone take a look at the vid? Is my cassette shot or the freehub?

trailangel

I would say you are missing a spacer behind the cassette if you tighten all the way and you can shift the cogs back and forth like that.

curbtender

+1

SethB

Hmm. I thought the splines on the freehub were responsible for the rotational movement, and the spacers handled translational movement? So the spacers would keep it from sliding in and out on the freehub.

I did look online at a new cassette and couldn't see any additional spacers on it that I don't have. Either way, I don't have it and the LBS forgot to put it on when I had my freehub replaced.. I do have some plastic I can make one out of though, I will go this route.

SethB

So I looked up a new one, counted 6 spacers, went outside and counted 6 spacers.. I don't think I am missing any. I'm going to disassemble the cassette and see if the splines on the freehub are worn or if the cassette is worn.

Iride01 

I'm not sure why the movement you show in the video would be what you are hearing while going over bumps. Chain slap or cable slap still seems more likely. Any seat bag with straps or zippers loose hitting the frame? I had a click that matched my pedal cadence that I puzzled on for months. Found out it was the metal zipper pull of my seat bag hitting the rear brake caliper.

Got a friend with same size wheel and cassette that'll let you swap temporarily?

curbtender

I'm not sure this is the problem, but the shimano 10 speed 6600 has a taller groove for use on their aluminum freehub. Any chance you are putting a 6600 cassette on a 6700 freehub?

SethB

Sadly I have nothing else on my bike, so rules out straps, zippers, etc. I have checked the cables, all is good there. Nice and snug and won't go anywhere. Chain slap I ruled out by wrapping the part of the frame near the chain with a small towel. Sound is still there.

I'm also not sure why this movement is causing the noise, but I don't notice is as much when I am in the bigger cogs.. And somewhat makes sense, if the bumps rattle the cogs, they can move rotationally as well as translationally, the latter being the louder of the two.

Also, no friend to borrow from

Well, I did need a new freehub, and I didn't notice this till after they put it on. The LBS didn't have a new one, they had a used one they put on (this one is in WAY better condition than mine was.. ha.. oops). So I do wonder if there may be some inconsistencies with the two? I never had this freehub off so I will be taking the cassette off and inspecting each individual cog on the freehub for play and fitment.


When I am finished working today I will go out and take it apart. What is really concerning is how tight the lock ring is, yet there is that play. I wonder if I am bottoming out with the lock ring somewhere preventing me from fully tightening down on the cassette.

alcjphil

When you take it apart, check to see if there is a 1mm thick spacer behind the cassette. These are supplied with Shimano cassettes and are needed to prevent the sort of play you are experiencing even with your lock ring very tight

UKFan4Sure

I had this one time and was missing a spacer. It would only rattle when I was in the higher (smaller cog) gears.