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Discussion Starter #1
I've had three XTR M9100 12 speed shifters break on me, all in the same manner. Two were warranty replacements for the first broken one. The latest replacement only lasted about 2 weeks before breaking.

What happens is the shift lever (long one) intermittently stops shifting--just pushes in with no resistance, no clicking and doesn't engage the shifting mechanism. Inside the shifter is a little metal rocker that's supposed to be held closed by (?) a spring. I think the spring breaks and stops holding the rocker closed. (The rocker when closed catches the teeth of a shift wheel.) The red arrow in the picture shows the little tooth end of this rocker lying in an abnormal, open position. Gravity can close the rocker, so once the problem starts, it happens intermittently after that but can still manage to shift on and off.

I've notified Shimano USA every time, but they haven't told me that anything is changing with the design of the shifter. Has this happened to anyone else?
 

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No issues for me either. About 10-11 months of year round use. First at the 11spd setting, and then at 12spd for the past 6 months.
 

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Two years, 2000 miles on two shifters, no problems at all.
 

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Discussion Starter #5
I'm riding with the 10-45 cassette and a 28t chainring. The lowest gear isn't just a bailout and I'm in it a lot on hilly rides.Shimano redesigned this new generation of shifters to hard-stop when at the lowest gear--the 45 tooth for me (used to be at the highest gear). So, I hit the hard stop many times a ride. Wonder if repeated shifts against the hard stop is what's leading to failure at the pivot of the rocker arm. The pivot in the broken shifter is wobbly, not just unsprung.
 

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Discussion Starter #7
The model I'm referring to is the sl-m9100. It's only been out for a year or so. This is the XTR 12 speed version. Is that what you're using?
 

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Discussion Starter #8
This is from my email to Shimano Tech Support:
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I'll also add the following observation about the m9100 design. All prior generations of Shimano mountain shifters give your thumb instant feedback when you're at the end of the line for easier gears (chain on the most inside cog). The long shift lever "gives" via a soft, sprung, 1 cm sag. Your thumb knows that there aren't any gears left to shift so you don't push too hard on the lever needlessly thinking that another gear is available.


In the new m9100 generation, there's a hard stop at the end of the line that doesn't feel any different then the prior shifts until you push hard on the lever and realize you're out of gears. This encourages hard pushes against the stop, looking for another gear many times on a hilly ride. (The futile pushes would be even more frequent when riding with the 10-45 cassette because you're in the 45 more often than you would be with a 51 tooth inner cog. I ride with the 10-45 "Rhythm Step" cassette.) Force* on the little downshift rocker gets transmitted to its pivot and eventually something breaks--either the pivot or its spring. So the pivot is too weak for a mountain bike shifter that doesn't give you immediate feedback when there's no more gears left to shift.


Hope this is helpful to you in explaining the problem to the design folks in Japan.
 

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This happened to the Shimano XTR M9100 12 speed trigger shifter that came on my current bike also a few months ago.

It had been in use for 5.5 months when the large downshift paddle lost all its clicks. The small upshift trigger still worked, so it could change onto a smaller rear sprocket and it stayed in gear, but it wasn't possible to change onto a larger rear sprocket as there was no resistance or clicks. The large downshift paddle just moved freely.

There was no warning at all that this was about to happen. The shifter went from working normally, with no obvious problem, to not working mid ride. The last shift I did before it failed was a multi shift (pressing in the large downshift paddle to change down several rear sprockets at once) and that was it no more shifting. That was somewhere in the middle of the cassette fortunately as I was 2 hours ride from home at the time so had to ride home slowly stuck in gear.:(

The shifter went back under warranty to Madison (The UK distributor for Shimano) so I didn't open it up.
 

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Discussion Starter #10
That's exactly the issue! I knew this had to be more widespread than Shimano originally told me (as in 'never before') when I first reported it about 3 months ago. I think every rider that's had this happen needs to call Shimano Tech or Warrany support and report the issue with as much detail as possible.

This is clearly a serious design flaw and Shimano is going to have to replace a lot of these shifters over the next many months. Folks who haven't had this happen to their shifters yet should expect it to happen at some point in the future after enough shifts against the hard-stop low gear have occurred. In your case, I think the pivot got damaged after many hard-stop shifts and finally suddenly gave out during a normal shift. Once this happens, the shifter is toast and cannot be repaired, either by the end-user or a bike shop.

Thank you for your report.
 

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I'm riding with the 10-45 cassette and a 28t chainring. The lowest gear isn't just a bailout and I'm in it a lot on hilly rides.Shimano redesigned this new generation of shifters to hard-stop when at the lowest gear--the 45 tooth for me (used to be at the highest gear). So, I hit the hard stop many times a ride. Wonder if repeated shifts against the hard stop is what's leading to failure at the pivot of the rocker arm. The pivot in the broken shifter is wobbly, not just unsprung.
That's what I'm using, too. I also hit the hard stop many times on a climb as I check to see if I have one more gear available.

good thing xtr stuff has a 3yr warranty. They probably said they've never heard of the problem before because of a couple factors. First being that Shimano's warranty doesn't necessarily require them to track down what the issue is before accepting it. They take in stuff if it's within the warranty period pretty willingly. Also, the person on the phone probably hasn't been given the information that the engineering folks have yet. So it very well might be the first time that particular person you're speaking to has heard of this issue. It's not a super common thing, as it's the first I've seen anyone say anything about it. Looks like you've managed to rustle up another example, but it took a couple days.
 

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Discussion Starter #12
You're exactly right about this. It's hard for me to believe that Shimano Japan doesn't already know about the problem. If they do, they clearly haven't put out a service bulletin on it. Probably hoping it stays a rare event. But there's no question the shifter needs a redesign.

Shimano Warranty has been great. No questions asked whether you contact them directly or go to any bike shop that sells Shimano components. I'm relieved that XTR carries a 3-year warranty, but I won't be satisfied until there's a redesign that fixes the problem once and for all and those redesigned XTR shifters are on my own machines.
 

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Discussion Starter #13
4th shifter broke: cause is clear

Riding yesterday, my 4th XTR sl-m9100 shifter has broken in exactly the same manner. During the ride, with no warning, the long downshift lever loses its resistance and pushes all the way in with no downshift. This starts very intermittently but rapidly becomes frequent--as in every 2nd or 3rd shift attempt.

I took this shifter apart and have clearly identified the defect. It isn't the rocker pivot as I previously thought, and I doubt it has anything to do with pushing against the hard stop (see above). It's the tiny pivot return spring that breaks. I have no idea why this happens. This spring definitely needs a redesign by Shimano. I'm including two pictures. One is a zoom out. At the bottom of the pic is the area I zoomed in on. In the closeup, the yellow arrow points at the abnormally open rocker that should be closed in order to engage the downshift toothed ring. The red arrow points at part of the broken pivot spring.

Once the spring suddenly breaks, the rocker closes by gravity only. Vibrations from trail chatter help it close, but only intermittently. That's why the shifter, once this little spring breaks, sometimes downshifts and sometimes completely fails. I've notified Shimano USA about this directly. Hopefully, a future redesign will fix this.
 

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Riding yesterday, my 4th XTR sl-m9100 shifter has broken in exactly the same manner. During the ride, with no warning, the long downshift lever loses its resistance and pushes all the way in with no downshift. This starts very intermittently but rapidly becomes frequent--as in every 2nd or 3rd shift attempt.

I took this shifter apart and have clearly identified the defect. It isn't the rocker pivot as I previously thought, and I doubt it has anything to do with pushing against the hard stop (see above). It's the tiny pivot return spring that breaks. I have no idea why this happens. This spring definitely needs a redesign by Shimano. I'm including two pictures. One is a zoom out. At the bottom of the pic is the area I zoomed in on. In the closeup, the yellow arrow points at the abnormally open rocker that should be closed in order to engage the downshift toothed ring. The red arrow points at part of the broken pivot spring.

Once the spring suddenly breaks, the rocker closes by gravity only. Vibrations from trail chatter help it close, but only intermittently. That's why the shifter, once this little spring breaks, sometimes downshifts and sometimes completely fails. I've notified Shimano USA about this directly. Hopefully, a future redesign will fix this.
Thanks for sharing this info.

I don't have the issue yet but I do have a few doubts on this exact shifter.

Is the inside always covered with so much white grease. When I opened mine it was even more than in your last picture. I have opened several previous generation Shimano shifters, none of them have visible trace of grease like this. I was just wondering if It is there just to help "coverup" the design flaw or reduce the chance it fails?

About the hard stop. I don't know if I understand you correctly. My shifter does allow a little more push at the lowest gear so that I know it is at the lowest, just like any previous XT/XTR. Did you check your RD low limit screw because it is actually the part that allows this "over push". If you had set it too tight the RD won't move any further when the cable is pulled by the lever and that puts all that stress on the internal mechanism.

And something might related to your problem: when my new XTR 9100 shifter came, I found it stuck on the downshift quite a lot, especially on 10-9 and 6-5. The resistance was so big that if it felt like I was gonna break something. It eventually shifted with huge thumb force, but only in 2 gears. And all this happened both with the cable in or removed. Now it sounds like the rocker arm could have been obstructed by some deformed parts. But I really couldn't tell with all that grease.

And strangely when I fully installed everything and was adjusting it, the obstruction was gone. Now it shifts to every gear with the same resistance but I am not sure if everything inside is fine , or the parts might have just been grinded enough to conform now. Now I am afraid the weakened parts will fail on me just like on you someday.
 

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You're exactly right about this. It's hard for me to believe that Shimano Japan doesn't already know about the problem. If they do, they clearly haven't put out a service bulletin on it.
Doesn't surprise me at all. They are run like an automobile company at this point. "nobody has heard of any problem" until it ends up killing dozens of people or a double digit percentage of them are failing and they can't claim ignorance anymore, but they'll still blame the riders as long as humanly possible. Wouldn't surprise me if they employ more attorneys than engineers these days.
 

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Discussion Starter #16
Thanks for sharing this info.

I don't have the issue yet but I do have a few doubts on this exact shifter.

Is the inside always covered with so much white grease. When I opened mine it was even more than in your last picture. I have opened several previous generation Shimano shifters, none of them have visible trace of grease like this. I was just wondering if It is there just to help "coverup" the design flaw or reduce the chance it fails?

About the hard stop. I don't know if I understand you correctly. My shifter does allow a little more push at the lowest gear so that I know it is at the lowest, just like any previous XT/XTR. Did you check your RD low limit screw because it is actually the part that allows this "over push". If you had set it too tight the RD won't move any further when the cable is pulled by the lever and that puts all that stress on the internal mechanism.

And something might related to your problem: when my new XTR 9100 shifter came, I found it stuck on the downshift quite a lot, especially on 10-9 and 6-5. The resistance was so big that if it felt like I was gonna break something. It eventually shifted with huge thumb force, but only in 2 gears. And all this happened both with the cable in or removed. Now it sounds like the rocker arm could have been obstructed by some deformed parts. But I really couldn't tell with all that grease.

And strangely when I fully installed everything and was adjusting it, the obstruction was gone. Now it shifts to every gear with the same resistance but I am not sure if everything inside is fine , or the parts might have just been grinded enough to conform now. Now I am afraid the weakened parts will fail on me just like on you someday.
The hard stop at low gear isn't a derailleur adjustment issue. It's the actual design of the shifter. The prior generation m9000 shifters had a soft stop that "told" your thumb there were no gears left. True there's a little tiny movement in the lever now at full low, but it feels just like the prior shift so it encourages you to try harder to shift. In any case, I don't think this is the cause of the tiny pivot spring breakage. Mechanically, looking inside the shifter while pushing hard on the long lever at the low gear spot, the rocker pivot itself is solid. There's no way a hard push will over twist the spiral spring. So it's a mystery, but a recurrent one.

Inside these levers there's a moderate amount of thin white grease. That doesn't cause problems. I had one lever, before it broke, that was very stiff and notchy until I sprayed some lubrication through the cable plug hole. That fixed it.
 

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Discussion Starter #17
Doesn't surprise me at all. They are run like an automobile company at this point. "nobody has heard of any problem" until it ends up killing dozens of people or a double digit percentage of them are failing and they can't claim ignorance anymore, but they'll still blame the riders as long as humanly possible. Wouldn't surprise me if they employ more attorneys than engineers these days.
Luckily, this is a rare mountain bike part design defect that's unlikely to cause a crash. I think the big issue for Shimano is going public about the defect and having a recall, or just replacing a sh!t-ton of sl-m9100 levers. They definitely know about the problem now. My guess is that they'll quietly replace broken shifters under warranty and do a small redesign to eliminate the flaw. It's just a real pain because I can no longer trust these shifters not to fail in the middle of a ride without warning. In every other way, the new Shimano 12 speed drivetrain is totally kick-ass.
 

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And something might related to your problem: when my new XTR 9100 shifter came, I found it stuck on the downshift quite a lot, especially on 10-9 and 6-5. The resistance was so big that if it felt like I was gonna break something. It eventually shifted with huge thumb force, but only in 2 gears. And all this happened both with the cable in or removed. Now it sounds like the rocker arm could have been obstructed by some deformed parts. But I really couldn't tell with all that grease.

And strangely when I fully installed everything and was adjusting it, the obstruction was gone. Now it shifts to every gear with the same resistance but I am not sure if everything inside is fine , or the parts might have just been grinded enough to conform now. Now I am afraid the weakened parts will fail on me just like on you someday.
Let me be sure I understand, do you mean you were shifting it before installation and connecting it to the derailleur? If so, this could be a problem on its own. Many d̶e̶r̶a̶i̶l̶l̶e̶u̶r̶s̶ shifters will bind or jam internally if shifted with no cable tension or without a cable installed because the cable end carrier will swivel around and get out of position and jam against some other internal part, it can move into positions it was never intended to be in during operation if there is no cable in place and under tension to keep it in the normal position. This would not be a fault of the shifter, and not a warranty problem if it were forced to shift in this condition and something broke.
 

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Discussion Starter #19
Let me be sure I understand, do you mean you were shifting it before installation and connecting it to the derailleur? If so, this could be a problem on its own. Many derailleurs will bind or jam internally if shifted with no cable tension or without a cable installed because the cable end carrier will swivel around and get out of position and jam against some other internal part, it can move into positions it was never intended to be in during operation if there is no cable in place and under tension to keep it in the normal position. This would not be a fault of the shifter, and not a warranty problem if it were forced to shift in this condition and something broke.
As the OP, I just want to have it be clear that this was not the cause of the spontaneous shifter failures I had on the trail, described and pictured above. They were caused by an internal spring breaking or dislodging during normal use--what I believe to be a serious design flaw in the new generation Shimano XTR 12 speed shifters.
 

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Let me be sure I understand, do you mean you were shifting it before installation and connecting it to the derailleur? If so, this could be a problem on its own. Many derailleurs will bind or jam internally if shifted with no cable tension or without a cable installed because the cable end carrier will swivel around and get out of position and jam against some other internal part, it can move into positions it was never intended to be in during operation if there is no cable in place and under tension to keep it in the normal position. This would not be a fault of the shifter, and not a warranty problem if it were forced to shift in this condition and something broke.
I understand if the shifter is operated with a cable installed but not tensioned, the cable head tends to move out of place and jam quite often, given the overly tight spaces in the XTR shifter.

But I didn't find anything that will move freely to any incorrect position if the shifter runs without cable. The cable carrier doesn't swivel in the 9100 shifter, last time I checked. But I'll give a closer look next time.

My old XT shifter, taken off without cable, shifts smoothly to any gear smoothly with consistent resistance at any angle or even being shaked. If something gets stuck because of the free motion then it should have happened many times, just from gravity. But it never did.

But again the internal of 9100 and previous generation could be so different. The old XT shifter has a very clean internal and the parts and their mechanisms can easily be identified. The 9100 shifter has so many small pieces filling up the entire room that are so close and blocks each other that when it jams, I almost cannot tell why even directly looking at the inside.
 
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