I ordered some family bikes recently, and all were supposed to come specced with RD-M6000 medium cage rear derailleurs. The first one out of the box has an RD-M4120, which is a cheaper model, as far as I can tell, and doesn't include a gray clutch switch.

The next one had the RD-M6000, but in setting the bike up, it became clear that the M4120 was a lot easier to get dialed in. (I've adjusted plenty of rear derailleurs, and that first M6000 was stubborn for me -- and clutch was off.)

I'm wondering what the practical difference is in terms of performance and features. All these bikes will be used for fairly tame trail riding, snow, and some light (green dot) downhill runs. My first trail ride on the m4120 was perfectly fine, shifted well, didn't slap around much.

  • Adjust with clutch on — I find that the cable tension needs to be slightly higher to help get the derailleur moving up the cassette. What problems were you exactly having? As for clutch vs no clutch, that's a question only you, your riding style, and your terrain can answer.
    – MaplePanda
    Jan 18, 2022 at 21:26
  • I may try that. When adjusting, I was getting both skipping up to the next bigger cog prematurely AND shifts to smaller cogs that didn't drop. I was down to a single turn/stop on the adjuster fixing/not fixing it. It was just test ridden 3 miles and seemed pretty good. I'll check on it after a few more rides and try adjusting with clutch on. Jan 18, 2022 at 21:48
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    Personally I'd take issue if a bike was advertised as coming with a clutch RD but you got one without. Substituting with something comparable is one thing and it happens, but this is kind of a raw deal. Jan 19, 2022 at 17:20
  • I'm with you there, except for the fact that the 4120 seems to work better (with far less tuning work) than the 6000. These were cheap bikes, and CS from Framed appears to be nonexistent. I knew that going in though. Jan 20, 2022 at 16:16

1 Answer 1


It looks like it's mostly a 'generation' issue: the M6000 was the top of the previous Deore range. Given than the top of the current Deore range is now 1x12 with 10/51T cassettes (M6100), 11/42T cassettes have moved to the 'basic' Deore setups (M4120 without clutch, M5120 with clutch).

Otherwise, to summarize the spec sheets, the M6000 has a clutch and the M4120 doesn't. The M4120 is rated for 2x10-speed and 2x11-speeds setups, while the M6000 is 10-speed only (the GS rated for 1x10 setups with 11/42 cassettes and SGS for 2x10 with 11/36 cassettes).

I couldn't find any other difference.

  • Thanks, I'd seen that, but didn't know if there was something else I was missing. These are both 10 speed 11-42 setups (perfectly adequate for the fatbiking we'll be doing). Jan 18, 2022 at 21:49
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    Despite the "lower" model number of M4120, it is a model several years newer than the M6000. Shimano is known for trickle down technology so today's lower hierarchy components enjoy the quality and performance of yesterday's flagship stuff. That said, this is NOT the reason the M6000 was clunky to set up compared to the M4120. Other issues are causing the difficulty getting the M6000 dialed. As Nathan noted, I'd be questioning the seller regarding the clutchless M4120. Tame riding or not, it's an important aspect of 1x drivetrains. Delivering what's promised is important
    – Jeff
    Jan 20, 2022 at 11:10

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