SRAM 11 speed grinding derailleur

[rufusgti]

I bought a second hand mountain bike today.
It has a SRAM 1x 11 speed setup.

I've taken it on a short ride and can feel a grinding from the drive train. The gears shift faultlessly yet I've tried adjusting the cable either way and it has no effect.

The grinding is coming from the jockey wheel. If I gently push on the back of the cage to take the tension off it goes silent. Where's if I push the derailleur back to increase tension the noise gets worse. It's like the chain is moving accross rocks. Yet I've removed the chain and the jockey wheels spin smoothly.

What am I missing.

[Simes205]

Have you played with the B screw.
I know the 12 speed has a gauge tool for this.

[Insert Coin]

As above, it looks like the B screw adjustment -

https://www.parktool.com/blog/repair-help/rear-der...

[rufusgti]

Thanks.
The b screw was not correctly adjusted. I believe these should have between 12-16 mm clearance on the biggest gear. I adjusted it but it hasn't made any difference unfortunately.

[tvrfan007]

Perhaps a short video of the change of noise if you press the derailleur? I don't see much in the picture. Is the chain rubbing the derailleur cage side to cause the noise?

My advice would be to go back to square one and methodically check each step of hanging a derailleur and indeed changing jockey wheels.

Check the hanger is tight, check the mounting bolt tightness, check alignment isn't pissed (I.e. it's been caught), b screw, jockey wheel screws and indeed their free play condition, etc.

A loose screw makes for a screw loose.

Edited by tvrfan007 on Sunday 18th April 06:54

[nd0000]

Would suggest servicing the jockey wheels. The bearings might be full of mud that isn't superficially visible.

[BOR]

If you are completely convinced it's the jockey wheels, then you could check that they are installed correctly.

I think 11sp jockey wheels are installed in opposite directions Top/Bottom, and that the spacers are also different Top/Bottom.

There are markings on the wheels to aid correct positioning, but the SRAM guide should be online.

I have no idea why they would install the wheels like this, but obviously it's important for some reason.

• If you need to reset B-Limit, it needs to be done with suspension in Sag position.

[jesusbuiltmycar]

BOR said:

If you are completely convinced it's the jockey wheels, then you could check that they are installed correctly.

I think 11sp jockey wheels are installed in opposite directions Top/Bottom, and that the spacers are also different Top/Bottom.

There are markings on the wheels to aid correct positioning, but the SRAM guide should be online.

I have no idea why they would install the wheels like this, but obviously it's important for some reason.

• If you need to reset B-Limit, it needs to be done with suspension in Sag position.

It may be due to the narrow-wide teeth on the jockey wheel used in 1X setups.

[rufusgti]

Thanks for your suggestions. I went for a 10 mile ride today and although it's still not quite right it's better than it was. I showed some friends who thought the chain or the cogs are worn and not quite seating properly. But couldn't tell which was the worn part.
I'm wondering if the seller stuck an old chain on to sell the bike or maybe a new one and it's a little sucky or not seated.

Can't seem to post a video unfortunately.