# Knocking when coasting or pedaling



## d.misko (Jan 26, 2016)

Hi,

I have a Norco Threshold A1 with Shimano 105 components. The bike is two years old with 10,000+ KM on it. Recently it started making a knocking noise. The noise happens both when coasting or pedalling, seated or standing. The knocking sounds almost like something flapping in the wind onto the frame, but I can't see anything that would be flapping. I've always maintained the bike well.

I've looked around on my bike, tightened the cassette, re-greased the seat post and looked for anything else that could be causing the noise.

Has anyone else had a similar problem? It's driving me crazy.

Thanks,

Dan


----------



## jtmoney528 (Dec 11, 2014)

Did you try tightening bottle cage screws down? I have seen that cause a knocking noise with a water bottle moving the cage on the frame.


----------



## d.misko (Jan 26, 2016)

I've wiggled the bottle cage and it seems secure. I'll try tightening it before I ride home and report back.


----------



## velodog (Sep 26, 2007)

Out of true rim dinging a brake shoe? Loose or broken spoke? Valve stem clicking on rim?


----------



## aclinjury (Sep 12, 2011)

loose headset?


----------



## ghettocop (Apr 19, 2014)

Totally obvious, and hate to ask, but did you remove the dork disc?


----------



## loxx0050 (Jul 26, 2013)

I've had the wheel speed sensor magnet hit the Garmin Sensor arm when the spokes loosen up. That turned out to be a extensive fix (time wise) to get that wheel true again. 

Or, what about the ratcheting mechanism for the freehub? Can you replicate the sound on a stand?


----------



## ROAD&DIRT (Mar 27, 2009)

Saddle mounting bolt's - loose bottom braket?


----------



## The Weasel (Jul 20, 2006)

loxx0050 said:


> Or, what about the ratcheting mechanism for the freehub? Can you replicate the sound on a stand?


This would be where I look. I experienced a similar knocking sound. Turned out that I'd cracked both bearings in the rear hub. Do you have any instances of your derailleur arm pulling forward during coasting?


----------



## Roland44 (Mar 21, 2013)

aclinjury said:


> loose headset?


That's where I would bet, I saw it happen numerous times.


----------



## rm -rf (Feb 27, 2006)

We need more details.

Does the sound come and go, or is it continuous as long as you are moving?

A clicking or knocking or rubbing sound?

Is it faster when you go fast?

Is it in time with a wheel rotation?

You said it happens while pedaling or coasting, otherwise I'd ask if it was timed to a crank revolution.

Do you hear it if you hold the front or rear wheel in the air and spin it?

Any change if you press both brakes while coasting?


----------



## d.misko (Jan 26, 2016)

I wasn't able to replicate the sound on a stand but do think I found the source. A little while ago I had my bike in for a broken spoke. When they put the cassette back on they forgot the first spacer. It didn't start the knocking right away so I didn't think it was a result of that repair job. 

Thank you for all of your tips, I went through checking each one which finally led me to the missing spacer.

Thanks!


----------



## Cartoscro (Sep 10, 2012)

Was it shifting fine without the spacer? I would think with a missing spacer, there would be play between the cassette and freehub? If you rode it like that, the splines on the free hub may be toast.


----------



## velodog (Sep 26, 2007)

Cartoscro said:


> Was it shifting fine without the spacer? I would think with a missing spacer, there would be play between the cassette and freehub? If you rode it like that, the splines on the free hub may be toast.


They mightamaybe adjusted everything to work without the spacer, and now it'll be needing to be adjusted back.


----------



## Kerry Irons (Feb 25, 2002)

d.misko said:


> Hi,
> 
> I have a Norco Threshold A1 with Shimano 105 components. The bike is two years old with 10,000+ KM on it. Recently it started making a knocking noise. The noise happens both when coasting or pedalling, seated or standing. The knocking sounds almost like something flapping in the wind onto the frame, but I can't see anything that would be flapping. I've always maintained the bike well.
> 
> ...


Could be spokes rubbing together at the crossing point. Put a drop of oil everywhere the spokes cross and touch.


----------



## Lombard (May 8, 2014)

ROAD&DIRT said:


> loose bottom braket?



I would say we can eliminate the BB since the noise happens while coasting as well as pedaling.

Signs are pointing to one of the hubs.


----------

