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Discussion Starter #1
Hi everyone!I have a problem with my derailleur it's a shimano RD-M5100-SGS brand new and brand new bike.I adjusted it as I did with other derailleurs but it only shifts properly half cassette ,from half cassette it starts to try to climb the next cog.any suggestions?1x11 drivetrain.....thank you!
 

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It could be that your derailleur hanger is slightly bent and needs adjusting. Happens more than you think, even on brand new bikes.
 

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Discussion Starter #3
It doesn't look bent isn't it?maybe doesn't look aligned with the cog because I was messing with the barrel adjuster while riding 😅and I just noticed that the cable housing doesn't have a gentle curve...it wasn't like that last time I adjusted it
1912613
 

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It doesn't look bent isn't it?maybe doesn't look aligned with the cog because I was messing with the barrel adjuster while riding and I just noticed that the cable housing doesn't have a gentle curve...it wasn't like that last time I adjusted it View attachment 1912613
Mine was bent ever so slightly and caused all sorts of shifting problems. Couldn't see it until the LBS hooked a derailleur hanger adjuster tool to it and tweaked it. Cost me nothing, took them 5 minutes to fix.
 

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Discussion Starter #5
I checked again but it really looks parrallel to the cassette...maybe tomorrow I remove the derailleur to check if there are swarfs from factory🤷I read in another post someone had that swarf problem...
 

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Shimano 12 speed derailleur cages are misleading at a glance, they look way out of line but it works well.
It's really hard / impossible to tell if a hanger is bent usually, get an alignment tool on there to check. They're reasonably priced, if you use it a few times it pays for itself.

The photo of your cable at the derailleur says it all though. I reckon 100% thats the problem.
Is it full suspension? Did you leave some slack under the bottom bracket?
Check it at full compression and see how much cable housing (and inner cable) you need. Might have to start fresh if it's too short.
My bike is notorious for the shift cable housing rubbing through the carbon bottom bracket over time without enough slack. Good luck.
 

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Discussion Starter #7
I think it could be the problem because last time I adjust it the cable was ok and shifting ok for a while...yes it's full sus and it makes sense to leave more cable under the bottom braket! didn't think about that!good job guys!tomorrow I try and I come back here to bother you all😁
 

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Here's my RD-M5100 for comparison. It looks bent but it's as-new, not ridden off the property yet.
Hope the cable housing sorts you out. It'll be pulling tension on and off the derailleur with suspension movement.
Happy to help, let us know how you go.
 

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I just installed XT 12 speed on my bike. Yes the derailleur does look bent when you look at it but that's the design intended. Like @trel said I would guess that it's your cable. That's a really tight awkward bend going into the the stop on the derailleur and will definitely caused shifting issues, hard lever feel and stiff movement of derailleur. I would get a new cable and housing and leave a nice easy loop where it goes into the derailleur. They smoother the loop the better it will shift. If that's how you received the bike the tech that installed it needs to be slapped.
 

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It doesn't look bent isn't it?maybe doesn't look aligned with the cog because I was messing with the barrel adjuster while riding 😅and I just noticed that the cable housing doesn't have a gentle curve...it wasn't like that last time I adjusted
I agree they are supposed to look bent and twisted, and here is why. BTW I would blame the derailleur hanger as well

 

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Absolutely the hanger should be checked. I personally would start with replacing the cable and housing and see if that resolves the issue. Looking at how that cable is routed especially where it enters the derailleur I'd bet that's more of an issue than the hanger. It looks like the ferrule is being pulled out of the derailleur the ferrule should be going straight into the derailleur with no tension on it.
 

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This is one of those things that might be impossible to diagnose on the internet. There are a ton of possibilities, all of them pretty simple fixes for a good mechanic but based on nuance and feel. Take it to someone trustworthy, they can probably sort it out in a few minutes.
 

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This is one of those things that might be impossible to diagnose on the internet. There are a ton of possibilities, all of them pretty simple fixes for a good mechanic but based on nuance and feel. Take it to someone trustworthy, they can probably sort it out in a few minutes.
Just make sure it's not the same guy that installed that cable😆
 

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I would still change that cable and housing. It needs to be done regardless. The tension on the cable end isn't letting the spring pull the derailleur back down the cassette.
 

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Absolutely the hanger should be checked. I personally would start with replacing the cable and housing and see if that resolves the issue. Looking at how that cable is routed especially where it enters the derailleur I'd bet that's more of an issue than the hanger. It looks like the ferrule is being pulled out of the derailleur the ferrule should be going straight into the derailleur with no tension on it.
that housing is WAY too short.
1. Replace the housing
2. Start again with the adjusting screws

if that doesn't fix it, check the hanger alignment
...then start again with the adjusting screws

If it's a new bike, whoever sold you the bike should fix it at their expense. If you did it yourself, it's a good lesson.

Also, use Shimano SP41 housing - it's the best

Go well :)
 

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Discussion Starter #20
Yes but first I will try to se if the housing is just too much outside on the handlebar side and try to slip it through the frame to the bottom bracket..if its too short I'll change it!thank you all!!! I'll let you know!
 
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