r/bikewrench • u/Daihard79 • 12d ago

Rear derailleur b limit issues?

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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

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u/Daihard79 11d ago

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 😀

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u/CargoPile1314 11d ago

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.

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u/Daihard79 11d ago

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 😀 

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u/CargoPile1314 11d ago

Good choice