Annoying rattle thats driving me nuts!!

tatman69

I have had the front derailleur altered by my LBS as it was too high and was rubbing on the chain.There is a rattling noise and I cant work out for the life of me where it is coming from. It sounds like the front derailleur but I can shake the bike and it doesnt replicate the noise.Also when im not on the bike (turn it upside down) and just pedal it really fast by hand it doesnt make the noise, so its obviusly weight related.

Any help would be appreciated.

diy

Is this a full sus or HT?

Have you checked the chain ring gap between the teeth and the front mech guide? Somethimes the chain rings can graze or chew on the mech, if its been set too low.

And if its a full sus, static sag affects the angle of the rear axle which in turn affects the angle of the chain on to the rings, which in turn affects how it clears the guide.

Is the rattle in every gear?

tatman69

Its a HT and yep its happening in every gear.

"Have you checked the chain ring gap between the teeth and the front mech guide? Somethimes the chain rings can graze or chew on the mech, if its been set too low."

Wouldnt the above happen if pedaling when stationary?

paulbox

If the noise is related to the chain rubbing on the front mech there is a good chance that you won't be able to re-create it with the bike upside down.

tatman69

Ok thanks I think your probably right...which means I need to take it back to my LBS as they serviced the gears on Sunday

Chunkers1980

Take the front mech off and see if it happens.

On my old deore the cage (whole pivot system) had developed a rattle - bin and new one solved it.

diy

tatman69 wrote:

Wouldnt the above happen if pedaling when stationary?

Unlikely, because the chain is under tension when you ride it. You could try applying the rear brake a little to simulate road load.

Also alu frames are amazing at bouncing sound. Sometimes a creaking seat can sound like a problem with the back wheel.

tatman69

Spoke to LBS they reckon try moving the front mech up 1-2mm and said I wouldnt need to change the tension on the cable...does that sound right???

Chunkers1980

No, if they atlered it and it's not right they should adjust it again. But they are not responsible if it not an adjustment issue - it could just be buggered.

diy

OK this can be a right pain in the a to get right.. On the one hand you want enough clearance of the teeth to stop them chewing the mech, on the other you don't want the chain fowling the guide. Sometimes its easier to set the mech at a slight angle (e.g. tail inward) to the chain rings, so that you can have it closer to 1mm without the teeth chewing or the chain rubbing the guide.

The guide should be 1-2mm from the top of the teeth (width of a penny)


see: http://www.parktool.com/repair/readhowto.asp?id=75

tatman69

Thanks all.

I took it back to LBS this morning and the guy kindly ran through a quick service of the front derailleur and it is fine.

I noticed when riding last night the sound seems to be coming from back wheel...checked the sprockets..all ok nothing seems loose etc Just cant replicate off of the bike.

The guy from my LBS showed me there was a very small amount of play in the rear hub which i will get looked at but didnt think that would cause the rattle!!

The Rookie

It could if the play in the hub meant that the chain line was changing......

Simon

tatman69

And that wouldnt happen if the bike was pedalled without a rider?

submityournentries

okay i think u said this, but not sure so ill add my 2 cents i had the same kinda noise and it went away when i tightend the lock ring on the cassette. i think u said u had checked this, but if not give it a tighten and make sure its FT hope this helps

nicklouse

tatman69 wrote:

its happening in every gear.

then something is way off.

too many variables. LBS time.