alexk_il

I have Shimano M8000 11-42t cassette, thinking to upgrade it to 46t. Can I buy only the 46t cog and swap it or do I need to buy a new cassette? Somehow can't find conclusive info in Shimano website.

​​Please ignore the obvious challenges with the chain length, FD and RD capacity. I am aware of those and know how to mitigate.

shelbyfv

Is your 42t separate from others? That would be a clue.

cobba

What you need is a section that consists of 3 sprockets, the part number is on the exploded diagram.

https://si.shimano.com/en/pdfs/ev/CS...8000-3854C.pdf

alexk_il

Thanks, that's exactly what I need. Strangely, the cost of this part is almost the same as the cost of the whole cassette. Blimey!

Darth Lefty 

The bailout jump on the Shimano cassette is a big shift and you might want to look at the Sunrace version

alexk_il

Ohhh, thanks, you are right, I missed the last jump from 37t to 46t. Really?🤦🏻‍♂️

Found a good deal on Microshift XLE H113 11-46t cassette, only £20 in the UK. Any reason not to use it and stick with other vendors?

Clyde1820

Just wondering ... Are you moving from Shimano 2x11 to 1x11? You probably already know, but Shimano's M8000 derailleurs specify certain max cassette size (ie, 11-42T with 2x11 vs 11-46T with 1x11).

https://bike.shimano.com/en-US/produ...M8000-SGS.html

alexk_il

My current setup is 40/28t and 11-42t and I am planning to stay with 2x. Just want to see how far I can push the limits of my RD/FD setup.

Anyway, Shimano M8000 specs shows total capacity of 47. I'm currently on 43, so in theory moving from 42t to 46t should still keep me within the specs. If it works, I might try pushing my luck even further with 40/26t on the front, just for fun. If not, I can always go 38/26t to get it back to specs. Might be tempted to try 38/24t too for an extra challenge.

Clyde1820

My ulterior motive for pointing out the 42T thingy was: I've got the M8000 2x11 setup with the 11-42T cassette and 34/24T. Gearing is already pretty low but, due to old injuries, even lower ain't a bad thing. If it turns out the 11-46T cassette functions flawlessly for you, then I'd love to hear your view of how it works, how smooth it shifts.

alexk_il

You might be close to the point of diminishing returns, your gear ratio will improve by (46-42)/42=~9%.

For me it's a bit better, if I change the front chainring from 28 to 24 and go from 42 to 46 at rear I should get about 25% improvement, which should be more noticeable.

It's up to you, of course. I will let you know how it works, might take a bit of time though.

​​​

alexk_il

Got the cassette, started with my existing 28/40t chainrings. Cou​​​​​ldn't make it work yet. Something isn't right with the SGS cage angle and the distance between the top pulley wheel and the sprockets.

I can actually tune the B-screw on my M8000 for really smooth shifting from 11 to 46 and back, but only either with the large or the small chainring at front. But not with both.

Ordered Wolftooth goatlink 11speed extender, hope it will fix the issue.

alexk_il

Got it working now, kind of, see below. Here is my setup now:

• R7000 brifters, JTech Shiftmate adapters
• Rear
  • RD-M8000
  • Sunrace 11-46t cassette
• Front
  • FD-5801
  • XT 40/28t cranks

Anyway, found this thread 11-51t with 2x, it inspired me to spent more time tuning the chain lenght, H/L limits, B screw and cable tension. All works fine now, shifting is relatively smooth, cross-chaining works too, I can use big-big or small-small without any drama or extra noises. In fact, the only way for me to know I'm cross-chaining is when I run out of gears on my shifters. 😂

Why "kind of"? It doesn't want to downshift to 5th sprocket, neither on big nor on small chainring. There's something strange here, all other gears work fine. No idea why, maybe something isn't right with my setting Jtek Shiftmate adapter.
​
I can still shift-down by two sprockets and go up one if I really need that gear, so I'm not worried about that for now.

I might try adding the 15t pulley wheel and/or Wolftooth goatlink push it to work with 40/26t. That's how they tuned the 11-51t with 2x GRX, maybe it'll help to n my case too.