My new frame has a four-bar back end, and having moved all the bits off my old hardtail the deore rear mech is of course bumping into the seat stay.

Presumably shadow type mechs are a solution, how about SRAM ones? Not sure everyone is a fan of shadow – are some better than others?

some mechs come with a little rubber bumper. Bit of inner tube and a zip tie would get the same result.

One these new clutched mechs? Pretty sure SRAM have released one too now.

So are you just having clearance issues? 4-bars aren’t automatically incompatible with any mech design so it’ll be something specific to your frame… But I’m not really clear what the problem is tbh

Surely if the rear mech is hitting the chainstay your chain is too short. You haven’t allowed for chain growth when fitting it.

So are you just having clearance issues?

The top end of the mech is bumping against the bottom edge of the chain stay (not seat stay as I typed above – that would be alarming), because the stay kinks downwards towards the pivot the mech and that part of the stay and pivot end up in very close proximity.

Surely if the rear mech is hitting the chainstay your chain is too short.

perhaps….. but not because the chain is tight – the mech isn’t being pulled against the stay by the chain – its jiggling against the frame not being pulled against it

OK – have you tried letting the air of the shock, putting the chain on big rear, big front and fully compressing the suspension to check chain growth? If the chain is too short then the mech could be pulled onto the chainstay if it’s too long the mech might be moving about too much.

Are you sure it’s the mech and not just chain slap? The new Shadow+ mechs should solve that.

Is the rear mech old? It’s spring could have lost tension.
Could be the B limit adjustment.

def the mech – in any gear too, so happening when the chain is relatively slack

I’ve got this on an old hardtail. Some old inner tube zip tied to the mech is the only thing that sorted it for me.

Have a look at the pictures here and compare them to your mech when the suspension is compressed on big big etc.

The bike in the picture is a 4 bar too – http://www.pinkbike.com/news/Tech-Tuesday-Chain-Length-Basics-2012.html

“top end of the mech is bumping against the bottom edge of the chain stay”

I’ve had this on hardtails and four-bars

Shadow solved it (not tried shadow plus). It would seem shadow takes a different swing-path sort of thing and it doesn’t hit the bike like non-shadow did

Why don’t people like shadow mechs?
Chop the cable to 30mm excess as per instructions and mine have been great

Have a look at the pictures here and compare them to your mech when the suspension is compressed on big big etc.

I think maybe you are talking about the other end of the mech neninga – those pictures show the jockey wheel end of the mech being pulled forward towards the stay by a short chain. I’m talking about the top knuckle of the mech – on my bike the pivot on the stay is quite low relative to the axel – so the pivot and the knuckle of the mech sit next to each other even when the chain is slack

you are definitely going to have to take some photos, I don’t think you’ve you got the mech mounted properly.

Try a sram mech,New type 2 is amazing,almost silent even on the roughest of tracks

will perhaps take a pic in the morning if I’ve got time – but mech is mounted as it should be

Having had a google I understand which bit you mean – the bulbous knuckle on the upper body. It seems to be an old style Deore thing with some frames (made worse with too big chains and incorrect B limit adjustment).

As above a new Deore/SLX/XT Shadow mech should sort it.

I had this with a Deore mech on my Enduro. When stationary the mech would sit less than 2cm from the horst link, this ment that she. Riding it would make a terrible noise banging off it. Fitted an SLX shadow and not had a problem since.