Great thread and first post! It helped me sort out that problem. I am even lower than the mark and it shifts like butter - super fast and fine, and even no issues with back pedal - I have to do 7-8 whole turns before the chain drops, if it drops.
One slight problem stays however. When I am on the 51-st there is a slight rub of the derailleur in the spokes, but just on a single place, not the whole thing.
If I make it not to rub, then slight shifting problems appear - hesitation from the 9-th to the 8th cog or from the 10-th to the 9-th, have to double check.
Let me know if you have this issue.
I am with an oldschool 135 rear end if that matters. With a 34 front, I don't have a use for the 51-st cog, but I might use it for a few minutes in very steep climbs.

Merry christmass boys and girls, have a great one comming!!!

 

Merry Christmas to you Ixaxaar

It's annoying that you have that rub in the 51. Solutions that come to mind are:

1. re-check the derailleur hanger alignment, in case it's causing the problem.
2. install a e.g. 1mm spacer behind the cassette to space it out (ensuring that the chain and/or smallest 11t cog doesn't hit the chainstay/dropout)
3. get "creative" with the 1 spoke/spoke pair that the derailleur hits...creative in terms of bending that bad boy of a spoke out out the way...and doing any re-truing of the wheel that's required...it's a pure "brute force and ignorance" strategy...but if that's what it takes to be safe, then you have to do what you have to do!!

Could you post a few pics of the rub?

Also, what chainline are you using. What ring on what crank?

 

Hey, thanx for the reply!
The derailleur hanger is 100% alright. What kind of spacer are you talking about?
Actually, the rub is only present when I'm on the trail and when I'm on the bike. When the bike is on the workstand - there is no rud I can hear or see. I am not a heavy rider - 70 kg.
I'm using the Shimano XT8000 cranks with an absoluteBlack 34 oval.

 

I'm thinking of these types of spacers:
https://www.amazon.com/Wheels-Manufacturing-1mm-Cassette-Spacer/dp/B0025UINFC
https://www.evanscycles.com/shimano-1mm-hg-cassette-spacer-EV220571

To see which spoke(s) is/are rubbing you could mark the spokes with the likes of chalk or whiteboard markers, or whatever else will easily rub or clean off.

For the sake of absolute clarity, are you saying that you've aligned the der hanger with a an alignment tool?

If nothing else worked, you could "mis-align" the hanger in the vertical plane to the extent that the the mech no longer hit the spokes, and see how the shifting was....

 

Hi Ixaxaar,

I'll repeat what I said in my first post. Check that the der hanger is properly aligned. You need to KNOW that it is verses THINKING that it is.

If you look at any of many threads here on MTBR about shifting problems. The two things two check first are likely to be (1) der hanger and (2) replace the cable and housing. If the der hanger isn't in the correct position then there isn't a baseline from which to diagnose anything else. This is especially true of 12 speed, which is very sensitive to set-up.

Here's an article that compares various tools.
https://cyclingtips.com/2016/08/best-bicycle-derailleur-hanger-tool/
I use a basic one, which does have a little play, but provided I use the same process at each measuring point, it works well.

Let us know how you go.

As I mentioned once in my first post, I think that this slight rubbing is a slight safety issue - with some combination of frame flex &/or suspension compression and/or sticks getting stuck and/or your mech cage being bent and/or the hanger getting (furhter) misaligned, your set-up is much more likely to have the derailleur fully involve itself in your wheel. This never ends well, and least you'll end up with is walking your bike and a non-trivial repair bill.

I was asking about chainline for my own interest, it shouldn't have anything to do with the mech rubbing on the spoke(s).

 

I’ll go to the bike shop and see if the der hanger is alright, I am not sure if they have this tool. Very interesting article indeed.
Cables and housing are brand new as well as everything else, so I don’t think the problem is there. Might be the der hanger, I should buy a spare anyway.

 

Fixed it with the limit screw it was set too far by the spokes, just a slight turn and it works like magic now. How did I not came with this earlier :lol:

 

Glad that you got it sorted

 

This is an amazing thread. Thanks for being a shining light. I'm doing something similar.
https://forums.mtbr.com/drivetrain-shifters-derailleurs-cranks/hybrid-shimano-sunrace-1x12-drivetrain-conversion-1135057.html#post14710143

I still have two questions. The first relates to the chain line. What is your chainline? You mention an oval chain ring. What chainline does it give you?

I'm fitting an SLX crank with a chainline of 52mm but the Absolute Black chainlink is dished and drops that to 51mm. I was thinking of moving the chainline another 2.5mm by repositioning one of the 2.5mm bottom bracket bushes to the ND side.

My second question is more theoretical. You mentioned how you were not able to get a good shift by following Shimano's alignment mark.
I'm trying to understand the reason. I thought if they are both 51 teeth sprockets their OD would be the same. Isn't that ultimately what matters that the chain can clear the teeth properly ? I'm not questioning you just trying to understand why the Shimano and Sunrace cassettes would behave differently.

 

My second question is more theoretical. You mentioned how you were not able to get a good shift by following Shimano's alignment mark.
I'm trying to understand the reason. I thought if they are both 51 teeth sprockets their OD would be the same. Isn't that ultimately what matters that the chain can clear the teeth properly ? I'm not questioning you just trying to understand why the Shimano and Sunrace cassettes would behave differently.

Clearing the cogs is only PART of the b-screw adjustment. The idea is that you're adjusting the b-screw so the chain matches the profiling of the cassette teeth optimally, too. There are lots of little things that need to line up right. The Shimano cassette and the Sunrace cassette are not exactly identical in all ways, so it makes sense that you might need to adjust for them subtly differently.

 

I already consider myself a fine specialist concerning the drivetrain, I managed to get it work smoothly as a normal shimano xt cassette, but that was achieved within two months of almost everyday struggle with the damn thing.
I own the cassette since december last year.
So basically, you have to lower the cassette a bit under the mark and then fiddle with the limit screw until it shifts perfect.
I must add, that you have to fine tune the system once in a month, but it is alright. I am by no means a fine mechanic,so if I can do it - you can do it. Just need to be patient and be careful, becouse the derailleur is very sensitive to the smallest change you make with the limit screws.
It works even better now, some months after the chain and cassette have broken in together.
As for why although identical cassettes, I think the guys from Sunrace made their cassette slightly different due to patents and stuff. I am sure the can make total replica of this cassette, but then they might get sued from Shimano becouse of patents. And it's up to the dear customer to find out how the damn works best. They could've at least done that, but anyway...I hope you sort out the things.
Make sure to use the Shimano 12 speed chain as it is specific and the cassette was made to work best with it.
Good luck and if you have more questions - hit us

 

Hi, did you need to adjust both H and L limit screws? Can I ask what your chainline is?

 

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


34T Oval chainring.
2008 Specialized Rockhopper

Can I please ask what brand chainring you're using and on what crank and what your resulting chainline is?

 

COVID-19 situation is going to delay my replies a bit.

Deckas 34T oval narrow wide chain ring
Chainline is roughly - 48.5mm

As for the answer for the theoretical, I honestly don't know. My only assumption is the "ridges/profile" on the side of the cogs of the Sunrace cassette does not match with Shimano's Hyperglide+ (due to patent reasons) which resulted in an adjustment in both B and H/L limit screws that is different than Shimano's recommended parameters. I can assume that had I used a Hyperglide+ cassette, that the screw adjustments would be exactly as the Shimano's instructions had recommended.

I don't know what the technical term for the ridges is called, but here's a pic I found online.

 

I am using the Shimano xt 8000 crank with an absolute black 34 oval. I don't know the chain line. About the limit screws - yes, adjust both, but the low one is that does the job. Adjust it as Shimano says and if does not work - play with it until you get it working. But make really, really small turns, because it is very sensitive.

 

My chain is slow to climb from the 7th cog to the 8th cog. It is also very slow to drop from the 12th cog to the 11th cog. If I tighten or loosened the cable tension adjuster, one problem gets better but the other gets worse. The problem is worse with the clutch engaged even though I have loosened the clutch a lot.

My chain rides on the outside of the eight cog which explains why it is hard to go from the 7th to the 8th. The chain looks to be centered on the other cogs.

This is with the B screw much looser than the Shimano spec. That improved shifting a lot but it didn't solve the remaining problems.

 

Play with the High limit screw, it should be a bit more to the outside But small turns as it is very sensitive. Mine shifts perfect everywhere.

 

Thanks! It works fine now. I loosened the B screw and the H screw a little more and now it shifts in and out of every gear nicely.

 

Marin actually specced the 11-50 sunrace cassette on their Rift Zone 3 with 12spd SLX drivetrain. They are now replacing them for free with the CSMZ800.

 

I got my bike back from the LBS after a free cassette replacement from Marin, and on the 11T cog the derailleur looks like this with the chain behind the main pivot. Am I correct in thinking that the chain is too long?

 

I got my bike back from the LBS after a free cassette replacement from Marin, and on the 11T cog the derailleur looks like this with the chain behind the main pivot. Am I correct in thinking that the chain is too long?

View attachment 1343073

I adjusted my chain using the shimano recommended method and mine looked like yours. Here is a good article about Shimano 12 speed chain length.https://dansbikeblog.com/article/how-calculate-correct-chain-length-shimano-12-speed-drivetrain

I shortened my chain one full link (two half links) and now it looks better and shifts better. In the article there is a photo near the bottom and it shows how the cage should look when the chain is short enough.

Edit: If it works well as it is you might want to leave it as it is. These things are fussy.

 

I'm using the mz903 with slx derailleur. The middle cog won't shift to next large cog unless I loosen the b tension most of the way. Other gears are fine. I feel like that's not correct. Any ideas?
I'm using slx chain and wolftooth 32 tooth hg+ chain ring with Sram cranks. Also using new Derailleur hanger.

 

If you use the shifter to tighten the cable tension can you get the middle cog to shift correctly but then the shifting to smaller cogs sucks?

What shifter are you using?

 

Does my chain line look off?

Feels like the chain is rubbing against the chainring on the largest cog.

 

I have the same problem here with my brand new Shimano 8100 + chain HG+ 8100 + Z903 11-51T Sunrace cassette +XT shifter 8100. I have a 32T chainring from Wolftooth.
I can shift OK from 11 to 24T but then very hardly to 38T.
Playing the shifter barrel does not help.
Any suggestion?

 

Did you loosen the b screw? That makes a big difference.

 

t does make a huge difference. Not 100% as my 28T still rattles but close.....thanks!

 

Same here. It's just that one 28t cog that can't shift right. I have a brand new Derailleur hanger too.

 

I think they don't suspect the new hanger as much as they suspect what the hanger is bolted to.

 

That would suck if my frame or dropouts are bent. I've only put like 200 miles on this frame never crashed or dropped the bike.

 

i still hate my sunrace

 

It's a sub-optimal substitute for a shimano cassette which is designed to mate in particular way with their 12 spd chain. Mine works ok at the moment but I have a SHimano hub and cassette waiting to swap it out.

That would suck if my frame or dropouts are bent. I've only put like 200 miles on this frame never crashed or dropped the bike.

It could be the frame is very slightly misaligned from the factory, or the mating surface not perfect, or other variations in manufacture, or any number of things. This ultra wide range narrow spaced cassette design is particularly sensitive to any misalignment. A removable hanger is meant to be adjustable using a gauge. Best go ahead and adjust it.

 

so this thread had me resurrect my tinkering. I ended up rebuilding a hardtail I thought I never would and used the sunrace on.

So believe it or not, removing the wolfstooth extender got it to shift a hair better, I also added the 12s gx chain that had some life left in it.

result,,, is it will shift through all gears now with slight hesitation I can live with up shifting to the smallest cog, and going from second largest cog up to 3rd smallest cog.

side note, reducing the B gap to as small as possible while shifting cleanly to largest cog, also was a contributing factor

 

Mine has started making a ticking noise when the chain is on the 38t cog. It shifts up and down fine in all gears but is ticks on that one cog. The alignment from the der to the cog looks good. I don't want to use the b screw to bring the der any closer to the cassette because I don't want to risk my new xt der.

 

My derailleur is set pretty close to the cassette as well. When I drop a bunch of gears on the bike stand it hits the cassette and get caught. But when I'm riding I can drop many gears without issue.

 

Mine ticks on the 17-th cog, but not too much,slightly but rides perfect. BTw, I am not using that cog too often, so no problem for me. Everything works like a charm with the Sunrace cassette, the trick is to play with the H limit screw, the barrel adjustment and make sure to loosen the B tension screw so the teeth come on the half with the shimano mark on the derailleur At least, this works best for me.

 

I think this Sunrace cassette is not ready for prime time. They say it is designed to work with the Shimano 12S drive train so why doesn't it work better with the 12S drive train? If Sunrace got it to work well, they should include adjustment directions with the cassette.

I wish I would have gotten a full Shimano 11 speed drive chain instead of 12s. I'd rather have good shifting and quiet running than the extra gear and problems. I also don't like having my new XT derailleur closer to the cassette than recommended. Possibly another better solution is the SRAM Eagle 12 speed cassette with everything else Shimano 12S but it is all steel and weighs another 100g.

 

I think this Sunrace cassette is not ready for prime time. They say it is designed to work with the Shimano 12S drive train so why doesn't it work better with the 12S drive train? If Sunrace got it to work well, they should include adjustment directions with the cassette.

I wish I would have gotten a full Shimano 11 speed drive chain instead of 12s. I'd rather have good shifting and quiet running than the extra gear and problems. I also don't like having my new XT derailleur closer to the cassette than recommended. Possibly another better solution is the SRAM Eagle 12 speed cassette with everything else Shimano 12S but it is all steel and weighs another 100g.

I will probably upgrade to Shimano microspline and slx cassette. I was able to sell my old Sram setup and can now use that towards my Shimano setup.

 

Has anyone tried Sram chain with this Sunrace cassette? I'm about to purchase X01 chain with hard chrome plating due to it's durability.

I'm not sure about compatibility with Shimano chain here either. Sunrace has it's own "classic" design 12sp chain for MZ90 system. MZ90 *may* have same cog spacing as Shimano, but this new MZ903 (495g) cassette in contrary to Sram compatible MZX0 cassette is not described as "Shimano compatible" or something. I highly doubt that Sunrace has HG+ license and therefore should not be used with Shimano chain.

 

Has anyone tried Sram chain with this Sunrace cassette? I'm about to purchase X01 chain with hard chrome plating due to it's durability.

Yes, it wasnt really a game changer. The typical gx chain not the hollow pin version is all you need for a sunrace.

 

Given some of the discussion on this thread, I thought that I'd share my successful and positive experience with this cassette

Firstly my set-up.

Hardtail, chainstay lenght of ~17.8"
135mm rear hub
Chainline of ~50mm

XTR chain, using wax as lube
XT mech
XT shifter
Sunrace cassette.

I followed Shimano's instructions to the letter, both for the install of the mech (including der hanger), and for chain length.

My set-up works. No issues. No noises. No lags. No skipping. It just works. I don't have to think about it.

If you are having issues, and haven't followed Shimano's instructions to the letter, I'd suggest you do that.

 

....If you are having issues, and haven't followed Shimano's instructions to the letter, I'd suggest you do that.

We had no reason to start any other way. When the shifting was bad, moving the derailleur closer to the cassette made sense so that is what we did and it works. When I move the der further from the cassette, the shifting gets bad again.

I wonder if Sunrace improved the cassette and you have an improved version of it.