Cycling UK Forum

I have an 11-42 cassette with a Shimano SLX Shadow+ long cage derailleur. Recently, when I selected bottom gear (it's 24-34 at the front), there was a horrible grating sound. It's not a gear I use very often but I do use it and it was OK before (I changed the chain?). That's maybe why I've just noticed it. I traced it to the 42 ring being too close to the guide pulley but when I tried to increase the angle of the rear derailleur, the 'B' screw was fully in. I held the derailleur down a bit by hand and the noise stopped. I don't think it's anything to do with indexing or the H-L screws as all the other gears are OK. I put in a longer Allen bolt and this works but it's only just catching the cam/stopper (or whatever it's called). The only thing I've changed recently was the chain, about a month ago. Is there a better solution?

have you perchance made the new chain a link longer than the old one?

cheers

No, Brucey, it's the exact same. It was a link too long but I shortened it to match the old one.

Derailleur hanger extender for about £3 on ebay you're sorted.

Rob

I have half a recollection that I once solved a similar problem by putting the bolt in from the other side, so that the – slightly larger – head contacted the stopper. Or I may have imagined it! Maybe worth a try?

yes that might work, but doesn't explain why it worked before and it doesn't now.

Thinking about it nor does chain length; IIRC both RD-M670 and RD-M675 have the guide pulley concentric with the lower pivot, so clearance to the sprocket oughtn't be affected by chain length.

Maybe

- the pulleys have been changed and are different now?
- there has been wear where the adaptor bracket fits to the gear hanger and this has moved the RD slightly?


all seems very mysterious to me...

cheers

Is it possible to slacken off the B screw and slip in a thin spacer (bit of an ally drinks can or something, then do it up again to see, effectively, if a slightly longer screw would do the trick?

I was out on the bike today and tried bottom gear. The longer allen bolt is working and it'll do till I get a better solution. Thanks for your input.

I have an slx m7000 11 speed rear derailleur working well with a 50 tooth sprocket on my mtb, it worked with a 46t without adjustment but for the 50t I had to screw the normal B screw in a few turns.