[Evintos]

Shifting issues 12sp upgrade on HT (RESOLVED)

See latest posts for updates. RESOLVED 11/21/2019. See post #39 for final update.

I appreciate any input. The below is the problem I'm encountering.

Downshift (small to largest cogs) adjustments are great; smooth with no hesitation.

Upshifting (largest to smallest cogs) on the other hand is giving me one specific issue. Specifically, the best I've been able to do is the below. I cannot get the chain to shift from the 42T cog down to the 36T cog (single click of shifter). It will go from 42T to 32T with no issues (double cick of shifter). The derailleur is definitely moving.

It will also shift from 36T to 32T cog also with no issues. Whenever I try to fine tune with the barrel adjuster to get the 42-36T upshift to work, usually the upshifting or downshift of the other cogs suffers.
[HR][/HR]
Below is the best result I've been able to accomplish:
Downshifting
11-13-15-17-19-21-24-28-32-36-42-50 (good)

Upshifting
50-42-36-32-28-24-21-19-17-15-13-11 (just the one problem shifting from 42T to 36T cog)

[HR][/HR]
Parts:

Shimano SLX SL-M7100-R (new)
Shimano SLX RD-M7100 SGS (new)
SunRace CSMZ90 11-50T (new)
Shimano SLX CN-M7100 chain (length adjusted according to manual 4 links + quick link) (new)

34T Oval chainring.
2008 Specialized Rockhopper

 

[Brad]

Sounds like either dirty cables
Lazy derailleur spring
Dirty shifter mechanism
Also check that cable housing end caps have not split. Often this happens and you adjust your downshift to compensate but chase your tail on the up

 

[mcc666]

bended shifter hanger
wrong b-screw adjustment

those i would check

MCC

 

[PuddleDuck]

Echoing what Brad and m6 have said:

- did you use a NEW cable housing & undamaged end-caps?
- did you check the alignment of the der hanger?
- did you follow Shimano's instructions to the letter?

- is the chainring new? What brand is it?
- This issue might be the chain hanging onto the chainring...on the XTR 12 speed thread, if peeps weren't using a Shimano chainring, they either used a SRAM quickline...or a SRAM chain. Chainring manufacturers have/will release Shimano 12 speed specific chainrings

Re: running Shimano with a Sunrace cassette.
You're the first person I've read/seen do this.
- maybe the Shimano chain doesn't like the Sunrace cassette - perhaps try a SRAM chain
- Another less palatable problem might be that the Sunrace cassette doesn't play well with Shimano 12 speed spacing. The width of SRAM vs Shimano vs Sunrace isn't exactly the same.

I'm interested in your feedback.

 

[Evintos]

Inspected - Cable housing cap looks ok, holes are round and no damage.
Performed - Cable gave it a wipe down with a paper towel. No residue. Gave it a couple drops of oil down the cable into the housing.
[HR][/HR]

- Cable housing not new.
- Brand new derailleur hanger. Did not check alignment (I will need to purchase a tool in order to do so).
*Followed the Shimano instructions - see note regarding end adjustment screw (B adjustment).* https://si.shimano.com/#/en/iDM/MARD001/adjustment/TOC_ADJUSTMENT
- Deckas 34T oval narrow wide chain ring - new

*Regarding B adjustment instruction*
The instructions state "Align the white line on the inner side of the outer plate with the tip of the highest tooth on the largest sprocket."

Following that instruction gave me worse shifting performance. With it adjusted according to the manual, it would constantly skip every other gear no matter what cable tension I rotated the barrel adjuster to. I adjusted the B screw so that the tip of the teeth of the 50T cog is below the marking on the derailleur indicator.
[HR][/HR]

Update:
As of now it will shift through all of the cogs with the follow issue(s) (not quite sure what got me to this point. -

If I adjust the barrel adjuster for smooth upshifting (largest to smallest) there will be a downshifting issue going from the 36T (third biggest cog) to the 42T (2nd biggest) A quick click will cause a short shift and result in chain rub until I shift back to 36T or I hold down the shift lever until the chain properly seats. A press of the shift lever going slightly past the click will result in a normal shift.

The issue only appears in the 36T to 42T shift. I'm not sure if this is a quirk with the parts/design or a sign of a potential major problem.

A 1/4 turn counter clockwise of the barrel adjuster will fix the 36T to 42T shifting however, it will then result in a slow upshift from 42T to 36T that would require around 3 to 7 full revolutions of the crank arm in order to complete the shift.

One thing I'm considering is opening up the shifter to see if there is any loose screws. Would this be a wise decision? Would rather not compound any issues.
[HR][/HR]
My current shopping list includes:
- shifter housing
- housing end caps
- derailleur alignment tool

Should I also include a SRAM chain to that list or should I see how the above goes first?

 

[PuddleDuck]

That's some great debugging!

I wouldn't open the shifter, but you and others may have a different opinions. I haven't poked around in a 12 speed Shimano one, but I doubt that you'll do any damage...changing the cable requires opening the shifter.

I'd hold off on the SRAM chain for the time being.

• However, I'd check that the chain seats well on the chainring, especially at the quick-connector...especially since that's a generic Chinese chainring
• (as background, I spend way too much time chasing a rear shifting issue on an old road bike that was caused by a worn chainring).
• Per my original post, 12 speed Shimano chainrings have different tooth profiles to other 12 speed chainrings, and the quicklink is narrower than other quicklinks. See post 659 and 706 ]https://forums.mtbr.com/drivetrain-...drivetrain-shifters-derailleurs-cranks/2018-shimano-xtr-12-speed-1078844-4.html
  

I always prefer to start with a known baseline, hence, as you're planing to do:
- install new housing (please buy Shimano SP41, it's regarded as the best)
- new end caps / undamaged end caps (I don't use sealed ones, they only increase friction)
- confirm that the hanger is properly aligned (even if new, it may not be aligned on the bike)

Regarding the housing, it it one continuous run, or is it several runs? e.g. shifter -> start of top tube, end of top tube -> start of seat stay, end of seat stay -> rear der. If it's multiple runs, then the added friction may be causing an issue

Best of luck!

 

[J.B. Weld]

One thing I'm considering is opening up the shifter to see if there is any loose screws. Would this be a wise decision? Would rather not compound any issues.
--------------
My current shopping list includes:
- shifter housing
- housing end caps
- derailleur alignment tool

Should I also include a SRAM chain to that list or should I see how the above goes first?

Highly recommend not disassembling the shift lever, it's the least likely component to be causing your issue and even if it was you couldn't fix it.

Things I would do-

-check derailleur hanger with alignment tool, adjust as necessary.
-if hanger adjustment doesn't help I'd replace cable and housing.
-if that doesn't help I'd try a Shimano cassette.

I wouldn't try a sram chain, ime shimano works best with shimano drivetrains.

 

[Evintos]

Housing/cable routing is as such:

Shifter -> start of down tube (cable/housing, housing cap)
Start of down tube -> bottom bracket guide (exposed cable)
Bottom bracket guide -> end of chain stay (exposed cable + ferrule/rubber cover)
End of chain stay (housing cap) -> rear derailleur (cable/housing, housing cap)
[HR][/HR]
Order placed on Amazon (will arrive in a day or so) -

- SHIMANO MTB SUS Bicycle Shift Cable Set (states OT-SP41 housing)
- CycloSpirit Derailleur Hanger Alignment Gauge
- Forest Bykes Bicycle Frame Bottom Bracket Cable Guides
[HR][/HR]
Plan for when parts arrive:
I will leave the shifter alone.

Replace housing, bottom bracket cable guide and check and adjust derailleur alignment. I figure I might as well change the housing if I have to remove the derailleur for the alignment adjustment.

If function fails - I will replace the quicklink with a outer link.
[HR][/HR]
Does Shimano make a 12sp cassette that fits the HG hub? As far as I know, all of it is the new Microspline.

I'll have an update as to the progress in a couple of days.

Thank you all so very much! :thumbsup:

 

[Outhouse]

my sunrace cassette has issues on that cog too, worse with the m7100 due to the larger B gap.

Had issues with the M8000 but you could tune it out.

The cassette cog spacing is off on the second to third largest cog.

 

[Outhouse]

I cannot get the chain to shift from the 42T cog down to the 36T cog (single click of shifter).

Same issue that I have on my 11-50 11s sunrace. I found the cassette has cog spacing wrong.

On mine I use a popsicle stick as a feeler gage, and you can tell the difference and its a pretty dramatic difference.

For a 12s you may have to sand down the stick if you choose to check cog spacing as the 12s is thinner than the 11s

 

[Evintos]

Same issue that I have on my 11-50 11s sunrace. I found the cassette has cog spacing wrong.

On mine I use a popsicle stick as a feeler gage, and you can tell the difference and its a pretty dramatic difference.

For a 12s you may have to sand down the stick if you choose to check cog spacing as the 12s is thinner than the 11s

my sunrace cassette has issues on that cog too, worse with the m7100 due to the larger B gap.

Had issues with the M8000 but you could tune it out.

The cassette cog spacing is off on the second to third largest cog.

That is somewhat disheartening to learn. Hopefully I can tune it out.

Do you have any reference for what the spacing should be? I have feeler gauges and here are the measurements for my cassette:

Cog spacing measurement (in mm)

• 50-42 = 2.29
• 42-36 = 2.12
• 36-32 = 2.14
• 32-28 = 2.01
• 28-24 = 2.01
• 24-21 = 1.99
• 21-19 = 1.91
• 19-17 = 2.04
• 17-15 = 2.04
• 15-13 = 2.04
• 13-11 = 2.04

Note: Measurement isn't 100% precise. Spacing between cogs varied by as much as +/- 0.02mm depending on where I inserted my feeler gauges. The measurements listed above is what I believe is the best overall representation of the spacing between cogs (not derived from the mathematical average of multiple measurement points).

I also can't remember what the tolerance is of my feeler gauge set (I believe +/- 0.005).

 

[Outhouse]

most of the cogs were close on mine, just the one offending cog, which is magically the same as your offender

 

[PuddleDuck]

The cog spacing thing is weird. I haven't read of any issues with Sunrace 12 speed cassette and SRAM Eagle.

If it turns out that the Sunrace cassette just doesn't work with Shimano 12 speed (which would surprise me), then you could

1.swap in the Sunrace shifter and rear mech - https://forums.mtbr.com/drivetrain-...ers-derailleurs-cranks/sunrace-12-speed-drivetrain-any-experiences-1089697.html

2. Relace your rear rim to a hub like this and use a Shimano cassette (this is a 135mm qr hub, of course the hubs are also available in 142mm +): https://www.bike-discount.de/en/buy/shimano-fh-mt500-center-lock-rear-hub-135mm-847093

 

[PuddleDuck]

Housing/cable routing is as such:

Shifter -> start of down tube (cable/housing, housing cap)
Start of down tube -> bottom bracket guide (exposed cable)
Bottom bracket guide -> end of chain stay (exposed cable + ferrule/rubber cover)
End of chain stay (housing cap) -> rear derailleur (cable/housing, housing cap)
[HR][/HR]

If I were you I'd consider replacing this "split routing" with one run of cable housing.

I'd either
(1) drill-out or file-out the cable stops (in case you need it here's a search string for google to search MTBR site:forums.mtbr.com drill out cable stop )
OR
(2) zip tie the cable housing to the frame or cabe stops (noting that if you use zip ties, don't do them up so tight that they crimp the housing!)

 

[TwoTone]

I do have to ask, most of the benefit from the new Shimano 12spd is in the chain and cassette, so why go with Sunrace?

 

[Outhouse]

I do have to ask, most of the benefit from the new Shimano 12spd is in the chain and cassette, so why go with Sunrace?

Im guessing he doesn't have the microspline hub.

With this sunrace cassette issue I went XD hub and ran the eagle gx 10-50 cassette and chain, and love it.

FOR OP I used two different chains and derailleurs, and still had the issue since im 100% positive it is the cassette.

I even tried the ZTTO cassette 9-50, and while that cog misshift was fixed, it shifted like crap in the small cogs. The m7100 cleared that up to some degree, but the eagle group set shifts night and day difference every time perfect.

 

[Evintos]

I do have to ask, most of the benefit from the new Shimano 12spd is in the chain and cassette, so why go with Sunrace?

Short answer: was given gift cards for eBay and saw it sold as a set (cassette, derailleur, shifter, chain ring, chain), figure it would work since the Sunrace cassette was compatible with the HG hub (135x10 QR) on my current wheel.
[HR][/HR]
The long backstory:

My bike originally had a 3x8 Shimano Alivio that has served me well for 11 years (commuting). I had several cassette, chain ring and chain replacements during that time frame that were pretty much plug and play (just had to adjust derailleur limit screws).

Then I decided to finally take my XC bike onto some single track after deciding to get a suspension gravel bike for commuting. The 3x8 drivetrain had me absolutely frustrated.

Figure I would simplify things and went with a "ghetto" 1x conversion by removing the front derailleur, removing largest and smallest chainring and shortening the chain to proper length with this new setup.

Experienced frequent chain dropping especially in descents and what I thought were mild rock gardens. So I learned that narrow/wide chain rings combined with a derailleur with a clutch will solve that problem.

At the time, I could not find a 135x10 QR Microspline hub and found out that the Sunrace CSMZ90 is compatible with my current 135x10 HG hub and Shimano to me is synonymous with quality (fishing reels, drivetrain on other bikes have been all reliable) so I stuck with Shimano rather than go with the SRAM NX Eagle.

I incorrectly assumed the cassette, chain ring, chain portions would be plug and play with minor adjustment to the derailleur. A failure on my part.
[HR][/HR]
I'll switch to the single run cable housing via zip tie as per PuddleDuck's suggestion.

 

[Outhouse]

I incorrectly assumed the cassette, chain ring, chain portions would be plug and play with minor adjustment to the derailleur. A failure on my part.
[HR][/HR]
I'll switch to the single run cable housing via zip tie as per PuddleDuck's suggestion.

Most of the time the sunrace cassettes have a good reputation, the rest you picked are all good parts and future proofed you for a while. I think like me you just got a bad egg for a cassette.

I drilled out my cable stops ran a cable/housing all the way back, it made no difference at all in shifting quality.

 

[PuddleDuck]

I drilled out my cable stops ran a cable/housing all the way back, it made no difference at all in shifting quality.

It may not now, but given how 12 speed is sensitive to adjustment, more cable sections gives more opportunity for the ingress of dirt & dust & water, and more opportunity for housing fraying & distorting & rusting, and for damaged end caps.

Mid to long term, one piece of housing should increase consistency and reliability, and reduce service intervals.

 

[TwoTone]

what hubs do you have?