I'm trying to understand if its possible to fit a 9-speed 11-50T cassette (found one on Ali) on my MTB. The plan is to go 1×9. The problem is that I can't seem to understand the if a specific derailleur can handle that.

The rear derailleur in mind is Shimano M4000 long cage. Should I use a hanger extension? Will 11-42T be better for that?

Thanks for the help

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    11-50 with only 9 gears is terrible, you’d have ≥21% steps on almost all gears. The steps on a 11-36 are already pretty bad. Comparison: ritzelrechner.de/… – Michael May 6 '18 at 15:51
  • I wonder what the vendor of such a cassette recommends for a derailleur. It would be impractical to offer a 1×9 cassette without at least one compatible derailleur. Although even bigger manufacturers allow themselves to announce parts of drivetrain without making the rest of the package available or at least announced… – Grigory Rechistov Nov 30 '18 at 22:51
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    There is a simple and elegant solution to this problem, its called a double chain-ring – Andy P Feb 4 '19 at 11:11
  • @Michael It would be primarily intended for casual (non-racing), dedicated MTB use, primarily in regions where trails consist of a gravel road up the mountain, and then single track trails back down. You grind up the fire road in the biggest cogs, and then ride back down in the smallest few. Having intermediate gears aren’t really needed because flat pedaling is rare in these areas. 9 speed allows for a more robust drivetrain compared to 11 or 12. – MaplePanda Nov 9 at 5:00
  • @Andy P I’m sure you already know all about the 1x vs 2x debate. For people looking for the simplicity of 1x9, having a 2x up front kind of defeats that purpose. – MaplePanda Nov 9 at 5:03

10 Answers 10


https://bike.shimano.com/en-EU/product/component/alivio-m4000/RD-M4000.html says that derailleur will handle

  • Low sprocket_Max. 36T

  • Low sprocket_Min. 32T

ANSWER: You cannot run a 50 tooth cog with that derailleur.

You might be able to use a hanger extension, but that will make the small gears even worse. Wolf Tooth's Roadlink allows up to 40 tooth, and Wolf Tooth's Tanpan says 44 or 45 tooth is the maximum cassette size supported. Note these are for 10 and 11 speed.

If you're absolutely stuck on a 50 tooth rear cog, then you're looking at a SRAM 12 speed Eagle setup, which will not be cheap. Cassette and shifter must change, and its very likely your freehub won't fit the cassette, and then the OLD will be too large to fit in your frame. Not a good plan.

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I run a shimano m4000 with a 9spd goat link on a 9spd 11-50t cassette with no problems b screw doesn’t need to be fully wound in.

More recently, I’ve reverted to a 10spd SLX shadow+ mech sgs cage which I run with a sram x7 9spd shifter, giving even better shifting.

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  • Welcome to the site! Nothing beats personal experience. :) – David Richerby Dec 28 '18 at 15:24

Derailleur will not handle that, as Criggie says in his answer. Apart from that, an 11-50 9 speed would have horrifically big jumps between gear ratios.

1x systems only really became feasible with the advent of 11 speed drive-trains, and still sacrifice ratio jumps to get a full spread of ratios to some extent.

If you really want a 1x 9 speed, get a cassette a 9 speed derailleur can handle, then get a small enough chainring to give you the low gears you want, and forgo the higher gears.

BTW, Shimano provides tech specs for all their products (as Criggie linked to). This page is a good place to start looking for specs of a particular product.

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  • Concur - I've recently installed an alfine11 hub, which has 10 gears with roughly equal spacing and an 11th low gear with double spacing. Its surprisingly "normal" to ride. – Criggie Nov 30 '18 at 21:11
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    > 1-50 9 speed would have horrifically big jumps between gear ratios. That could just be from the P.O.V. of a road cyclist. (The P.OV. of a mountain cyclist is a murky realm to which I'm not privy.) – Kaz Sep 3 '19 at 22:59

I have to agree with Dave - 11-36 works like a charm, gear spacing is just right. A 11-40 cassette just works OK with the B-screw screwed in all the way or using an even longer replacement screw. I also tried an 11-42 which didn't really work well.

AFAIC the issue with the wide range cassettes reg. 9-Speed is that they have the cassettes but there are no (Shimano) derailleurs to shift it. At least not out of the box. You could try a Shimano 10-speed derailleur and if it doesn't work ok (which it likely won't), try tweaking it. There are howtos online with re-routing the cable for a different pull ratio. 11-speed derailleurs might be too narrow, chain-wise. You could also use a Sram 9-speed shifter with a Shimano 10-speed derailleur.

Trouble is, all of these solutions are rather expensive if you haven't the parts in the spares box. Rather than spending that much money on an exotic 9-speed solution that doesn't get better over time, invest it in a Sunrace 11-speed cassette and Shimano SLX derailleur plus shifter.

What you don't want is a solution based on hanging your derailleur lower and the Wolf Tooth link extensions don't work with 9-speed derailleurs. I tried it (and it's rather expensive too).

Best to stick to inexpensive 11/12-36 and a 30 or 32 NW chainring. Or try the 11-40, but that's the max you will be able to get working properly.

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Box Components have released a 9-speed 11-50 drivetrain (cassette, RD, and chain) for EMTBs (thicker chain and cassette to cope with the torque), and I think the gear jump ratios don't matter when it comes to mountain biking. Even Seth's Bike Hacks uses it, and he's a very nitpicky kind of guy.

What I don't know is if it's compatible with a standard 9-speed system. Box Components says it isn't compatible with Shimano and SRAM 9-speed systems, but I have a feeling they're just saying it for marketing purposes.

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21% gear spacing is not a problem. Shimano has over stated the need for tight ratios. The shifting won't be quite as smooth, I have an 8spd 11-40, but will be well within acceptable standards. 11-36 has never been a problem with 9 speeds and I usually have to double shift my 11-36 10 spd because the ratios are too tight.

You will have to use a hanger extender with a long cage derailleur. The warnings that the extender doesn't allow the RDR to track the cassette properly is also over stated. Shimano claims they do no testing with components other than their own. If you believe that Shimano wouldn't know. Obviously that is ridiculous.

Shimano has stubbornly lagged 2 to 3 years behind the market in the area of gear ranges. They don't belive in it and only participate well behind the market because they have no choice so pick another brand of RDR. There are many options.

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  • Whilst I don't agree on gear ratios, i totally agree about Shimano. They are an infuriating company that seem to want to make biking as inaccessible as possible to people with 'normal' power outputs. – Andy P Feb 4 '19 at 11:10
  • it's because Japan (where Shimano is founded) is in more of a road cycling thing, where gear ratio jumps are more important than gear range. – Gregory Leo Jun 15 '19 at 7:04

I looked at some offerings of such cassettes and what a vendor suggests as a derailleur for them.

An example of a cassette:

9 sp 11-50 cassette

Compatibility chart from the same page:

compatibility table

It looks that no 9- or 10-speed dérailleurs are compatible with that cassette, but they claim that some 11-speed ans 12-speed parts from both Shimano and SRAM may be used instead.

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I have used a RD-M2000 and 11-50 on 9 speed with hanger, but the very connection of the gear wire on the inside just touches the bigger cog when in 1 gear, otherwise ok (almost :-) Would probably try the RD-M370 instead next time

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I been using a Shimano Alivio M4000 RD paired to a 11-46T cassette for almost 3 years now and I didn't Have the issue that was being pointed here. Alivio m4000 has max 45T so just used hanger extension it works great. But going to 11-50 I don't think the Alivio RD can handle that. I don't know about the 2021 edition of the Alivio perhaps you can try that if you want a 11-50T Cassette. For me I am fine with the 11-46T cassette picture shows a 11-40T cassette which I used before upgrading to an 11-46T. No Hanger extension works well with no issuesenter image description here

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best way to go is to use sram 9v trigger (only sram) coupled with new generation clutch type derailleur - i use shimano slx 11v but also sram should go. Work like a charme with 9v cassette and chain, no adaptation needed.

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    Why is this best? I'm not saying you're wrong but, at the moment, your answer is basically "Trust me -- I'm a random person on the internet!", which isn't a great basis for anything. – David Richerby Sep 3 '19 at 18:07

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