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

 

bended shifter hanger
wrong b-screw adjustment

those i would check

MCC

 

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.

 

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?

 

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.

 

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!

 

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:

 

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!)

 

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.

 

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

 

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).

 

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

 

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

 

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.

 

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.

 

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.

 

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.

Yup.

I put 6,000 miles on my old bike with full length housing, I changed the cable and housing once...and it didn't really need it then. Typical non-full length housings have three times as many cable ends to get slowly crushed into the ferrules and effectively change the length of the cable.

 

what hubs do you have?

 

They're marked Specialized (stock wheels), no clue who actually makes them.

[HR][/HR]
Update:

TLDR: Problem with the 42-36T still present while riding. On a stand, with clutch on or off, I can tune it so that it isn't there and only has a minor shift hesitation.
[HR][/HR]
Details:

Cable housing changed to new OT-SP41. New end caps as well. Cable routing switched to one run continuous from shifter to derailleur utilizing top tube and zip ties (did not cinch zip ties all the way yet, the top tube has zip tie points for rear brake line which allows me to bypass the down tube routing and bottom bracket guide). Excess housing trimmed with Park Tool CN-10. Excess cable on rear derailleur left until tuning complete. I made sure to route the cable so there's only very gradual bends.

Derailleur alignment as follows -
Pre-adjustment values

• Y-axis - 5.01mm
• X-axis - 9.31mm

Post-adjustment values (Instructions says within 4mm, Park Tool video says 3mm. I figure below 1mm should be good enough for 12sp. Let me know if it isn't though, I'll take another go at it.)

• Y-axis - 0.75mm
• X-axis - 0.20mm

Unfortunately adjusting the derailleur hanger alignment and new housing did not fix the issue. While the shifting is smoother and I gained slightly finer adjustment of the derailleur per 1/4 turn of the barrel adjuster, the issue with the 42-36T persists.

Step 2:
Observe quicklink for issues with chain ring and cassette. Did not see any but removed/replaced it anyways. Unfortunately the problem still persisted. Reinstalled quicklink.

As I was cranking slowly, I can see that the teeth of the cassette will line directly on top of the roller of the links rather than bias closer in between the plates. I decided to add two additional links just to see what happens, contrary to Shimano instructions for chain length for Hardtails.
Before:

After:

Result was as follows - I was able to shift up and down the entire range of the cassette. Although there was still a small shift hesitation between the 42-36T with the barrel adjuster tuned for a smoother downshift. An upshift previously would require 3-7 crank revolutions in order to complete a shift. This time it was consistently 1 revolution which was acceptable to me. Shifting on other cogs were good. Retested with the clutch lever on and same results.

On the road test: Test conducted on poor condition city street (way bumpier than gravel, bunch of cracks, ruts and pot holes) and smooth sidewalk. Failure :madman:. 42-36T upshift would not complete at all. Test was conducted with clutch both on and then off with same results.
[HR][/HR]
To be continued:
I sent an email to Sunrace to see what they think. I'm concerned as to whether or not this is a common issue with the 46-36T transition as previously mentioned by Outhouse and perhaps a recall or warranty service required with the cassette.

At this point I haven't quite decided as to whether or not I should just live with it or go with a Sunrace or SRAM derailleur/shifter and save the SLX combo for a bike build.

 

while my 11s sunrace ha s the same exact issue in the same exact way and in the same place, I don't think its normal. id be curious to hear what they say.

I had mine tuned out for a 500 miles. Where it was workable. When I built my new HT 29er I could not tune it out. Even with 2 different derailleurs both new, and two new chains.

Wish I would have tried the sram 12s chain. Ive heard it cleans up some issues on 11s sytems

 

One really dumb thing to check (and I couldn't confirm if this is even an option for slx shifters) is that there's a little allen screw on the bottom of xtr shifters for use on 11 speed drivetrains. I was seriously ready to break stuff before noticing that mine was set to 11.

A couple other small observations that I've noted. Like many, I don't like to read instructions but I'd routed the cable the wrong way initially and was having trouble with downshifts. Make sure it's coming in like this...

(thanks for rotating my picture mtbr!!)

And this still shifts well on an Eagle cassette (xd driver on my burly wheels) and shimano chain (w/ 11spd race face chain ring).

 

Make sure it's coming in like this...

That does not look right in that picture, even though i know your right.

Hard to mess up the m7100, on the largest cog your cable is either right or its not

 

As far as this thread and the op's issue is concerned I think people are making too big of a deal out if the split housing thing because it seems fairly clear it isn't causing the problem here. Yes full length is better for mtb when fresh split housing works just fine.

 

Hi Evintos, sorry to hear that you still have the issue. I'm looking forward to hearing what Sunrace say

 

@Walt Disney's Frozen Head

I don't believe SLX has that adjustment feature for the shifter.

Pretty sure I got the cable routing correct. I haven't trimmed the excess cable yet. I wanted to make sure it shifted properly before I do so.

 

yes correct cable routing

 

Update:
Bad news I suppose. email response from SunRace came. On one hand, not what I wanted to hear but on the other hand, there is a HG hub compatible 12sp cassette compatible with Shimano.

At the time of this post, the products (CSMZ901 WA1, CSMZ902 WA1, CSMZ903 WA1, CSMZ800 WA1) are not listed on SunRace | Bicycle Drivetrain and Brake Components. Didn't even know they existed.

Cog information that I can find:
11-51t: 11-13-15-17-19-21-24-28-33-39-45-51

[HR][/HR]
At the moment, I can only find the CSMZ903 and CSMZ800 in stock. Ordered the CSMZ903 with estimated delivery on Sat. Nov 23.

The CSMZ90 I have now will be saved for a future bike build with a SRAM drivetrain.

Hopefully the next update will be one with a success story.
Thanks for everyone's help and thank you for following along on this journey so far!

 

Update:
Bad news I suppose. email response from SunRace came. On one hand, not what I wanted to hear but on the other hand, there is a HG hub compatible 12sp cassette compatible with Shimano.

At the time of this post, the products (CSMZ901 WA1, CSMZ902 WA1, CSMZ903 WA1, CSMZ800 WA1) are not listed on SunRace | Bicycle Drivetrain and Brake Components. Didn't even know they existed.

Cog information that I can find:
11-51t: 11-13-15-17-19-21-24-28-33-39-45-51

[HR][/HR]
At the moment, I can only find the CSMZ903 and CSMZ800 in stock. Ordered the CSMZ903 with estimated delivery on Sat. Nov 23.

The CSMZ90 I have now will be saved for a future bike build with a SRAM drivetrain.

Hopefully the next update will be one with a success story.
Thanks for everyone's help and thank you for following along on this journey so far!

Thanks for the update. I didn't know that those cassettes existed either...and i spend WAY too much time looking at bike stuff online.

It is good news though that Sunrace have a range of cassettes that are Shimano 12 speed compatible...and even replicate the 51T biggest cog

Once you get that new cassette, I have a feeling that your bike will shift like a dream :thumbsup:

 

some old info...

https://bikerumor.com/2019/03/30/sunrace-12-speed-prototype-derailleur-aims-at-xtr-xx-plus-11-52t-cassette/...and a very positive review of the Sunrace 10-51, including comparisons to Shimano's cassette's

https://www.facebook.com/notes/bird...second-review-sunraces-new-12-speed-mz903-and-mz800-cassettes/1082618701923679/

 

I use csmz903

And it works quite well.
I continue to test, the only thing I notice is that sometimes at 'up shifting' it took some time to shift (only at the middle cogs).
I think I need to adjust it again after break in.

https://forums.mtbr.com/drivetrain-shifters-derailleurs-cranks/sunrace-csmz903-11-51t-1116487.html

 

And it works quite well.
I continue to test, the only thing I notice is that sometimes at 'up shifting' it took some time to shift (only at the middle cogs).
I think I need to adjust it again after break in.

https://forums.mtbr.com/drivetrain-shifters-derailleurs-cranks/sunrace-csmz903-11-51t-1116487.html

thanks for the update, not sure how we all missed your thread!

 

My sunrace issues are solved. Bought a 12s 7100 shifter, to go with my m7100 derailleur and ended up getting a eagle 10-50 cassette used on ebay with low miles for 100 bucks and with the sram chain, this thing shifts a hair better then the complete eagle system on my other bike. It is a night and day difference from ztto or sunrace as far as quality. No way ill ever buy these cheaper products again when it comes to something where quality is required.

 

Hi, why you set the b tension lower than the marks, how it function when it was set as manual?

 

Thank for the accurate info, i will given it a try.

 

Hi Evintos,

I'm super glad that this worked out for you :thumbsup:

Also, thanks for posting such detailed info on the way you've set up the new cassette and how you've optimised shifting.