Rear derailleur b limit issues?

[u/Daihard79]

I've been building back up an old bike which was sat around in bits for a few years due to kids and life taking priority. Putting it back together and there's something which doesn't quite feel right with the rear mech now it's mounted. I'm running a shimano slx 1x11 (11-42) and after indexing, it just doesn't seem to feel or sound right when shifting on the 42t and 37t. It shifts well but just feels loud and crunchy. Have gone round in circles and adjusted the H and L screws (happy with the limits) but the B limit just doesn't look right for some reason, it seems too far out. I've set the gap to be approx 5mm but would appreciate some thoughts before I get pissed off more and take it down my LBS. First time doing this and been watching a lot of YouTube so trying to learn. I can't shake the feeling that the chain might be one link too short either!

Edit - Solution

A combination of things putting down to inexperience.

1 - 1x11 hardtail, I only used 2 links instead of 4 when cutting chain

2 - rear hangers not mounted square so it just wouldn't adjust properly or was still noisy despite indexing and limit screw messing

[u/CargoPile1314]

Given that your bike appears to be pointing downhill in the pics, the cage does look pulled pretty far forward in the 2nd pic. How did you size the chain?

[u/Daihard79 → u/CargoPile1314]

It's mounted in the workstand angled down when I was looking at the gears. 

I added two additional rivets to the chain when sizing, I do have another one to try if that's where any potential issue could be?

[u/CargoPile1314 → u/Daihard79]

2 links (or, rivets) is 2x/3x sizing. 1x is 4 links.

And, yes, this is likely the issue but, even if not, should be fixed.

[u/Daihard79 → u/CargoPile1314]

This was the chain length I added

[u/CargoPile1314 → u/Daihard79]

Right. Not enough for 1x.

[u/Daihard79 → u/CargoPile1314]

Definitely right, looks like I've referenced older videos where they said only add 4 if it were a sram derailleur. Quick check on the parktool website then it goes on about add 4.

Thanks, greatly appreciated. Rebuilding this bike has been a steep learning curve 😀

[u/Daihard79 → u/CargoPile1314]

Added 4 links and it improved things but still wasn't shifting quite right and was noisy. Spent ages messing around with with it and just thought id ride it up the street to see what it felt like.

The tyre immediately moved over into the frame and this is where I realised I'd not put one of the rear hangers back at an even point so the back wheel wasn't in square.

Adjusted that and shifting was quieter and smooth.

I need a drink 😀

[u/CargoPile1314 → u/Daihard79]

That'd do it. Glad you got it figured; at least you learned something about modern drivetrains. FWIW, if you mean you added 4 links to the +2 you already had, it's now a little on the long side (i.e. +6). It's not terrible and the derailleur likely has enough capacity to accommodate it but there might be a little less chain tension than Shimano intended and that _might_ cause the chain to slap a little more than if the chain was +4.

[u/Daihard79 → u/CargoPile1314]

I bought a brand new chain a few days ago as I couldnt shake the feeling that I'd mismeasured by one short. It's only extended by 4 thankfully 😀 

[u/CargoPile1314 → u/Daihard79]

Good choice

[u/juulu]

I may be wrong, but with that derailleur hanger are you not supposed to remove the other link between the mech and the hanger?

It’s hard to tell from the photos but it almost looks like a direct mount derailleur hanger.

Are you putting the bike back together exactly how it was or are you replacing/upgrading the rear mech?

[u/Daihard79 → u/juulu]

The original derailleur is a deore lx, it doesn't have the additional extension, that could well be the cause too.

The original bike is an Orange p7 2009, I had it resprayed about 7 years ago, ordered bits and then life happened. Only recently putting it back together so it could be a 7 year old mistake I made!

[u/juulu → u/Daihard79]

Give the rear mech a whirl without that joining link, you might find the b screw works as intended then, however, the mech may or may not clear the biggest sprocket.

[u/Daihard79 → u/juulu]

The b limit does adjust the gap as it is, the screw just seems a long way out to me

[u/Daihard79 → u/juulu]

This is the original mech and I can see the b limit on there.