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Just upgraded my rear mech and I'm struggling to get it to shift perfectly. I noticed that, viewed from behind, the cage is not perfectly parallel with the cassette. Instead it tilts slightly towards the wheel. Could this be a sign of a bent hanger?
It's a Deore RD-M5120-SGS (one of the new ones) with a Sunrace CSMX3 10 speed 11-46 cassette.
This is the best picture I could get:
Could this be a sign of a bent hanger?
Yes.
Buy a new one, as the only other way to find out is to get a shop to check it with an alignment tool, which will probably end up with you having to buy a hanger anyway.
Worst case scenario, if you buy a new one and it's still not right (in that case your Mech is damaged) then you have a spare hanger, which you should always have, anyway.
the only other way to find out is to get a shop to check it with an alignment tool, which will probably end up with you having to buy a hanger anyway.
Or just buy an alignment tool and fix it yourself - they're usually pretty easy to bend back in line (can't see your pic to see if it's properly wonky though). Large cassettes seem more sensitive to alignment so it's worth being able to check alignment and tweak it if your shifting goes off
If you're competent enough to change a rear mech you should buy an alignment tool, and it's always a good idea to have a spare hanger. The tool will be an investment you won't regret. Paving could do with a sweep too when you have a mo'....
Paving could do with a sweep too when you have a mo’
😂😂😂
I’ve got a spare hanger so will try that first. Failing that, I’ve been lusting after the Abbey HAG ... may have an excuse to buy one finally! 😁
Fitting a new hanger may or may not change anything.
Remember, the frame itself had to be spot on too.
Get the tool, I now count it as a must have tool with 12 speeds in particular.
OK, so I replaced the derailleur hanger, but now the cage seems to tilt outwards (away from the wheel) rather than inwards. I’m wondering if this might be because I’ve installed the hanger wrong?
It’s a Specialized ‘sandwich’ type hanger, the two halves of which are held together with a 2.5mm hex head bolt. The two halves start off parallel, but as you tighten the bolt the inner half tilts outwards slightly. Since the derailleur attaches to this half, it also ends up tilted slightly outwards.
Hopefully the images below will make the above a bit clearer. I have a feeling I’m being a cretin here, I’m just not sure how!
Just fitting a new hanger does not mean it’s all aligned properly.
A tool is well worth the small cost , or large cost if you want to be a tart and buy the Abby one
Straighten the old one.
May I just add my voice to the get a hanger alignment tool and sort it out properly.
I've bought one recently to rectify yet another child created banana hanger - should paint them yellow really.
I was quite surprised how much straightening they will take when done carefully.
I saw something on YouTube about the new Shimano mech cages bending inwards (by design).
I’ll have a look to see if I can find it....
(edit) here:
You might just find that you have clamped the gear cable the wrong side of the rear mech. I spent ages trying to work out why an 8100 rear mech wouldn’t shift properly and that was the reason! Go to the Shimano site and look at the dealer manual for clarity.
Thanks all, I guess I will need to get the tool so I can be sure I have a straight hanger. It just seems a bit of a weird design from Specialized. If you look at the second picture, just above that little bit of bare aluminium (the result of a chain loss incident before I knew how to set limit screws) you can see how a gap has opened up between the frame and the hanger. In the first picture (prior to tightening the little bolt) there is no gap.
In the first instance I think I will reinstall my original hanger since the new one doesn't seem to have improved matters.
Nitster, I'm fairly certain I've attached everything correctly. I followed all the steps in the manual since I'm fairly new to this game (as you can probably tell!).
That's very interesting Rich, when I get the bike out later I'll have a good look at the cage and see whether there is any intentional bend.
I'd second the alignment tool point. Had one for many years and it's been quite well used. Plus it does a job you can't do perfectly without it.
One other point to note might be B tension. The shimano 12 speed mechs in particular are quite sensitive to this being set right, and it's done differently to before (there's a marking on the cage to align to). If indexing is right but in use it just feels rough this might make the difference.
So it turns out I am actually a cretin. With the wheel in place, the two halves of the hanger are squeezed together and the outward tilt I mention above is eliminated.
On the other hand, RichBowman, you sir are a genius! The derailleur cage does in fact have a very pronounced outward tilt. It’s hard to capture in an image, but I’ve done my best:
With the new hanger installed, I now have perfect shifting in the stand. Looking forward to trying it out for real tomorrow morning.