Clunking mech on chainstay

-liam-

Morning everyone.

Is there anything I can do to stop the rear mech clunking in the chainstay when hooning down bumpy singletrack and rocks? Its really off putting and I've not noticed my mates bike doing it to the same level. (he is half a mile behind me though haha) Have I missed something setting the mech or perhaps I can put a link or or 3 back in the chain?

dunker

keep the chain tight using big chainring and big sprocket gears? no good if you want to pedal though.

-liam-

Exactly. I mean big ringing it on the at the front and small ring at the back when the mech is tucked up. Obviously you can't pedal all the time.

elPedro666

At the back of the mech, above/behind the high/low stop screws there should be another screw pressing onto a plate which sets the angle of the mech & should stop it clunking.

Check out Sheldon Brown or Park Tools for pics & proper instructions.

-liam-

elPedro666 wrote:

At the back of the mech, above/behind the high/low stop screws there should be another screw pressing onto a plate which sets the angle of the mech & should stop it clunking.

Check out Sheldon Brown or Park Tools for pics & proper instructions.

Is that what will stop it then? Setting the angle of the dangle ?

alfablue

Is the chain too long?

Put chain on large chain ring and smallest sprocket, jockey wheels should be in vertical alignment. Mech pointing back at the bottom = too long.

-liam-

Pic time.

These don't look in vertical alignment.

elPedro666

alfablue wrote:

Is the chain too long?

Put chain on large chain ring and smallest sprocket, jockey wheels should be in vertical alignment. Mech pointing back at the bottom = too long.

Is that a roadieism? It surely depends on the spread of the block - if it's a very wide ratio I'd be concerned you could end up too short doing it that way.

Stick it in the two biggest sprockets and there shouldn't be much movement left in the mech arm. Or take it out of the mech cage and do it properly - around the biggest ring and sprocket and add two links.

Doesn't look like there's anything basically wrong, even if the chain might be a bit long. Screw the b-stop adjuster in a bit (as above), maybe lose a link if it doesn't leave you too tight in big/big and it should be fine.

nicklouse

Shimano mechs do bump against the chainstays.

chain could be a tad long but around the two big cogs without the mech present and add one full link (including the powerlink)

stevieboy

Get a shadow rear mech, they don't slap the chainstays like the normal shimano mechs.

alfablue

elPedro666 wrote:

alfablue wrote:

Is the chain too long?

Put chain on large chain ring and smallest sprocket, jockey wheels should be in vertical alignment. Mech pointing back at the bottom = too long.

Is that a roadieism? It surely depends on the spread of the block - if it's a very wide ratio I'd be concerned you could end up too short doing it that way.

Stick it in the two biggest sprockets and there shouldn't be much movement left in the mech arm. Or take it out of the mech cage and do it properly - around the biggest ring and sprocket and add two links.

It could be a roadieism however it gives a correct chainlength for my mtb (11-34/44, 32,22 XT) setup. Your method is "more" correct however.

elPedro666

alfablue wrote:

elPedro666 wrote:

alfablue wrote:

Is the chain too long?

Put chain on large chain ring and smallest sprocket, jockey wheels should be in vertical alignment. Mech pointing back at the bottom = too long.

Is that a roadieism? It surely depends on the spread of the block - if it's a very wide ratio I'd be concerned you could end up too short doing it that way.

Stick it in the two biggest sprockets and there shouldn't be much movement left in the mech arm. Or take it out of the mech cage and do it properly - around the biggest ring and sprocket and add two links.

It could be a roadieism however it gives a correct chainlength for my mtb (11-34/44, 32,22 XT) setup. Your method is "more" correct however.

But yours saves splitting the mech...

alfablue

Or the chain

Bottom line is, is there enough chain length when on largest chain ring and second largest sprocket (on the basis that we wouldn't really intend to use largest to largest)? Park Tools suggest this is adequate:


I think there may be an understandable tendency not to shorten the chain to the optimum.

Note, full suss will probably require a longer chain - not relevant to OP though.

Soul Boy

Yup, you can't stop that mech clunking, though some of those style mechs do come with a little rubber bumper to lessen the noise (my old LX did). You could use a little tape or a frame guard (lizard skins springs to mind) on the chainstay to protect it a little and dampen the noise.

Not had any experience of SRAM, but Shimano Shadow mechs don't clunk about. So if you really want a quiet ride, get the card out.....

dav1

try adjusting the H screw on the back of the mech.
If it is not set correctly then the mech is free to hit the chainstay.

Info on parktools about the right setting, basically you want it to stop the mech hitting but not over do it to the point the mech moves too far from the casette for effective shifting.