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I came off the bike a little while back and the derailleur took a fair hit. The hanger was bent so much that shifting was basically not happening at all. I've straightened the hanger out out and set up the derailleur from scratch and everything is working as it should, except the chain is slipping in gear 12.
Try as I might I can't sort this bit out. I'm guessing the hanger is still a bit out of alignment, but could it be anything else? Saw another thread on hear about Shimano 12 speed derailleurs being a bit bendy, is there a way to check if it's that?
Any top tips or recommended YouTube videos to watch would be much appreciated.
SLX 12 speed, all matching parts the same age (6 months or so old) and chain and cassette aren't worn.
Thanks very much.
LBS will do it (properly) for a few quid
Did you use a proper hanger alignment tool? One of the best things in my toolkit. Means you can properly eliminate that from the cause. Cages do bend pretty easily, so worth looking at that once the hanger is straight. Also is the limit screw set correctly? Sometimes gets forgotten.
From the SRAM AXS shifting thread :
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iainc
Full MemberJust to bring this one back for an update. My AXS on my Levo SL wasn’t shifting great, I changed hanger and it was still a bit grumbly. On the back of this thread I bought the Park hanger alignment tool and low and behold after some tweaks it settled perfectly. Today I fitted a GX AXS to my 1 ride old drivetrain on my new HT, and it was also a bit grumbly. Took mech off and found hanger to be a bit off alignment. 10 mins with Park alignment tool, some tweaks, mech back on, perfect shifting…
Every day is a learning day. 😁
Posted 12 hours ago
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Even new bikes new a tweak fresh out the box - particularly 12 speed which is really sensitive. Your LBS should be able to sort it in a few minutes - I’d sometimes do it free for regular/nice customers.
Mech is probably slightly bent too unfortunately. I had a similar issue and there was no solving it, a new mech instantly made the issue go away
I think unless you have a fleet of bikes that you're forever crashing, mech alignment is one for the LBS IMO
I made an alignment tool out of a piece of old clothes airer, and a bolt from the tin of bolts and washers and brackets that one day may come in useful even if you don’t know what they were originally from.
Luckily I don’t need it very often, but it’s a pretty simple principle.
In the old days of 5/6/7/8/9/10/11 speed, I used to straighten hangers by eye or used a vice. Worked fine. Then 12speed came and 'by eye' isn't enough so I bought the park tool. Works well and couldn't really be without it now.
nickc
I think unless you have a fleet of bikes that you’re forever crashing, mech alignment is one for the LBS IMO
I would have a greed with you not long ago, never needed it pre 12 speed, but the length of 12s mechs amplifies any small misalignment. I wouldn't be without it now, well worth the cash. Lifeline one not that pricy.
Thanks for the replies, straightened by eye so might pick up a proper tool and see how I go. I’m not fit enough to be using 12th all that often so there’s no rush!
straighten hanger in a vise. Or replace, then align with tool (great device). I've often found that the poor shifting is cable friction, having aligned everything with the tool.
Once you have the tool, it might be the first thing you do any and every time you fettle with gears. It pretty much is for me. You want to start with perfect alignment so that's eliminated before you start changing other things, IMO. So I'd say it's a good tool to have for anyone, pretty much. I've had a cheap one from a CRC or similar own brand or unbranded, for a good decade. Used often. It's rudimentary, but so long as it's square along the shaft the rim checking pin thingy is on, that should be no issue.
Mine fouls one of my frames though on its hefty hanger bolt, it's got play and I'm not certain it's square, so I might upgrade it to something better one day.
Picked up one of the Lifeline / CRC ones in a sale a few years back (£25). Yes it does have a tiny bit of play compared to the Park Tool one but its sorted 3 bikes already and saved me 3 trips to the LBS.
As above, I routinely check alignment when doing a service. Setting up 12 speed is so finicky unless you have a perfectly straight hanger.
I picked up a super b derailleur hanger alignment tool which I think is the same as the lifeline one. It's got some play and I'm sure it's not as good as the park tools version, but it did the job. Got the hanger straightened and fitted a new gear cable while I was there. All sorted now, nice clean shifts and no chain slipping. Thanks for your help.
I’ve often found that the poor shifting is cable friction, having aligned everything with the tool.
I snapped off reach each last week (broke at bolt and left the bolt and part of mech behind) but hanger looked straight but could have been slightly bending inwards.
Shifting wasn't perfect and assumed hanger but then spotted very slight kink in cable housing caused when scooting home with mech hanger flailing about.
Replaced housing new cable and now perfect, still not sure if mech hanger is dead straight though.
(As an aside, having ridden brakeless fixed for the last 10+ years I have to say that gears and brakes are a constant faff aren't they)
Compared to the price of ‘normal’ park tools, I found it pretty reasonable at £60 for a
Big proper bike only bit of kit.
Taking stuff to the LBS is fine if it’s next door or open at midnight. I usually find stuff needs fixing the morning of a trip to wales or the night before.