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Bicycle rear derailleur compatibility - which rear shifters, cassettes and chains can it be combined with

Compatibility [04] Rear derailleurs

Updated: 06/10/2019.

This post explains bicycle rear derailleur compatibility, i.e. what derailleurs can work with which number of rear sprockets (cassettes) and which rear shifters. For explanation of other rear derailleur functioning and limitations, such as chain wrap capacity, read this article: Rear derailleur.


Basic terms and what to pay attention to

Most modern bicycles have index shifters, that work with a certain number of clicks. One click per gear change. That is moving the chain from one sprocket/chainring to another with each click.

In order for this to work, these things need to be in tune:

  • Length of cable that shifter pulls/releases with each click. This is called shifter cable pull.
  • Distance that rear derailleur (RD in the remainder of this text) moves laterally per 1 mm of cable movement. This is called rear shift ratio. E.g. if RD moves for 2 mm for 1 mm cable movement (pull or release), then the rear shift ratio is 2.
  • Rear sprocket spacing.

Not directly related to shifter-derailleur compatibility, but it is also crucial to use proper cables and housing. I wrote a post explaining shifter (and brake) cable and housing standards.

When RD compatibility is mentioned, it is all about it’s tune with the shifter cable pull and rear sprocket spacing. When it is all set up correctly, one click of the indexed shifter shifts exactly and correctly one gear (i.e. one sprocket) at the rear. Compatibility will be explained per number of gears and per manufacturer. If it is not noted otherwise, it is understood that shifter make and number of gears match the RD make and the actual number of rear sprockets. There are three major RD and shifter manufacturer standards:

  1. Shimano
  2. SRAM
  3. Campagnolo
  4. Rotor’s hydraulic derailleurs


1. Shimano

6, 7, 8 and 9 speeds

Rear shift ratio is 1.7, that is for 1 mm of cable pull/release, RD is moved left/right by 1.7 mm. Shimano calls this 2:1 ratio for marketing reasons.

All these RDs are compatible and any 6 to 9 speed RD will work perfectly with either 6, 7, 8 or 9 speed shifter. Regardless whether it’s a MTB, or road shifter, or RD. They are also compatible with Shimano 10 speed road shifters, except the Tiagra 4700 series.

Shimano Dura Ace from 1984 to 1996 period (6 to 8 speeds)

Rear shift ratio is 1.9. They are compatible only with Shimano Dura Ace shifters from the same period (that is for 6, 7 and 8 speeds).

10 speed ROAD RD

Rear shift ratio is 1.7, so it’s compatible with all the 6 to 9 speed shifters, as well as road 10 speed shifters. Same rear shift ratio. MTB 10 (and 11 speed) shifters won’t work well.

Exception is Shimano Tiagra 4700 10 speed road RD – it has the same shift ratio as Shimano road 11 speed RDs, so it will work only with Tiagra 4700 shifters and Shimano 11 speed road shifters.

Another exception is the new “gravel” group (with hydraulic brakes): Shimano GRX. Caple pull wise it’s the same as Tiagra 4700.

10 speed MTB RD

Rear shift ratio of this RD is about 1.2. It is only compatible with Shimano 10 speed MTB shifters and nothing else. Shimano calls this system Dyna-Sys.

11 speed ROAD

Rear shift ratio is around 1.4.  Only compatible with Shimano 11 speed road shifters.

The same shift ratio is used for Tiagra 4700 10 speed groupset, so it’s compatible with it as well, but not with other 10 speed road groupsets.

Rear shift ratio of 1.4 matches old Campagnolo ratio, but I haven’t tested this in practice.

11 speed MTB

Rear shift ratio is around 1.1. Compatible with Shimano MTB 11 speed shifters. Shimano calls this system Dyna-Sys, same as 10 speed MTB, but they’re not compatible!

It has similar rear shift ratio to SRAM 1:1 standard (explained later in this post), so it should match it as well, but I haven’t tried it yet!

11 and 12 speed MTB – Hyperglide+ (XTR M9100)

From summer of 2018 Shimano introduces a new Hyperglide+ 11 and 12 speed MTB standard. It comes with a new XTR M9100 rear derailleur, that only works with a matching shifter (which has an integrated 11, or 12 speed operation switch!) and Hyperglide+ 11 and 12 speed cassettes.


2. SRAM

SRAM has four RD families, with 4 different amounts of RD movement per cable movement (actuation ratios). So the only thing to pay attention to is actuation ratio. As long as the RD matches shifter’s actuation ratio (and vice versa), it will work fine.

First, less popular family of SRAM RDs are the ones compatible with Shimano 2:1 standard. Rear shift ratio of 1.7 means they will work with Shimano (and SRAM 2:1) shifters for 6 to 9 speeds (both road and MTB) and road 10 speed ones, except Tiagra 4700 10 speed road shifters.
RDs made in this standard were marketed as 6, 7, 8 and 9 speed models, though this is determined by the shifter – RD doesn’t care how many rear sprockets there are.

Second, more popular SRAM standard is 1:1, with rear shifter ratio of 1.1. This shift ratio is the same as Shimano MTB 11 speed RD (and shifter), so they should be compatible, but I haven’t tested this yet.
RDs made in this standard were marketed as 7, 8 and 9 speed models.

Third, newer standard is Exact Actuation. Rear shifter ratio is 1.3.
Marketed as 10 speed road and MTB , as well as 11 speed road.

Fourth family is X-Actuation, with 1.12 ratio.
Available as 11 and 12 speed MTB RDs 

EDIT: Based on this comment (on this very article) and provided links to SRAM’s website, Exact Actuation and 1:1 are the same thing. Will have to measure, check and confirm this.


3. Campagnolo

Campagnolo has two standards of rear shift ratio. Old 1.4 and new 1.5. Also, not every shifter pulls the same amount of cable with each click. With 10 speed for example, there is more cable pull for “slower” speeds, than there is for the others.  2.5 mm pull five times (from smallest 1st to the 6th sprocket), 3 mm for 7th and 8th, then 3.5 mm for 9th and 10th. 2.83 mm average cable pull per click.  🙂

Apart from that, as of 2014 (don’t take my word for the exact year), campagnolo introduces another 11 speed standard. Previous Revolution 11 and the newest Revolution 11+. They are not compatible.

Since Campagnolo cassettes sprocket spacing differs from other manufacturers’, it is hard to combine Campagnolo RDs with anything but the appropriate Campagnolo shifters and in most cases cassettes too.

Table of rear shift ratios for various standards:

Shimano standard – 1.7SRAM 2:1 – 1.7Campagnolo old – 1.4
Shimano 10 MTB – 1.2SRAM 1:1 – 1.1Campagnolo new – 1.5
Shimano 11 road – 1.4SRAM Exact Actuation – 1.3Campagnolo Revolution 11+ – N/A
Shimano 11 MTB – 1.1SRAM X-Actuation – 1.12 
Shimano Dura Ace 6 to 8 speeds – 1.9  


4. Rotor

Rotor’s hydraulic rear derailleurs are only compatible with their hydraulic shifters.

Related post – Bicycle rear hub compatibility:

Compatibility of bicycle rear hubs - which can accept what kinds of sprockets (cassettes)
Compatibility of bicycle rear hubs – which can accept what kinds of “sprockets” (cassettes)

Compatibility posts are also available in eBook (printable and Kindle) and paperback editions on Amazon:

Bicycle Drivetrain Compatibility on Amazon
Bicycle Drivetrain Compatibility on Amazon
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96 thoughts on “Compatibility [04] Rear derailleurs”

  1. Hi ,
    I am looking to replace my Shimano 105 RD-1050 . One of the links is broken. I am told a Claris RD-2000 SS 8 speed derailleur will work . I was wondering if a Sora RD-R3000-SS 9 speed derailleur would work or even a 105 RD-5701 ?

    Reply
    • Shimano 105 10 speed RDs (5700 series) is compatible with Shimano road and MTB RDs for up to 9 speeds (among other compatibilities), so it should work fine.

      So would the Sora 9 speed RD. And the Claris RD.

    • With the combinations I’ve tried, at least 2-speads fewer on the chain than what they are on the derailleur, there have been no problems (like 7 speed chain on 9 speed derailleurs).
      Haven’t tested the extremes, like a 6, or a 7 speed chain on an 11 speed derailleur. If I had an 11 speed RD laying around, I’d mount it and test, just to know. 🙂

    • Hi,

      I just finished the upgrade on my older Peugeot steel bike bike. It already had Shimano 105 group but it was a 6 speed free hub and the rear derailleur link failed so had to be replaced. Upgraded from a 6 speed free wheel to an 8 speed cassette on a new rear wheel. I used a 10 speed RD-5701 with an 8 speed cassette / chain and had an old Sora 8 speed shifter. Works great !! I bought an extra rear 105 10 speed derailleur ( just in case) since they seem to be phased out and the 11 speed have a different ratio 1.4 instead of 1.7 .

      Thanks for you help. None of the bike shops mechanics I spoke to said it would work . Great info here and proved it does work .

    • Glad to hear it has helped. 🙂

      Sourcing (new) parts is both complicated/difficult and rather expensive compared to average local pays in my country.
      So we have to find ways to improvise with most things.

      A lot of the combinations I have tried and confirmed to be working are against manufacturers’ recommendations.
      I believe manufacturers make recommendations a bit more “strictly”, both in order to avoid any potential law suits, and to make more profit – “forcing” people to buy the new stuff.

      As far as mechanics go – it makes sense for them to recommend what manufacturers recommend – to avoid any complaints, or law suits.
      Also, it is practically impossible to keep track of all the different systems and “standards”. The word “standard” has become meaningless in the cycling industry, since even one same manufacturer keeps making new stuff to be incompatible with the old stuff.
      I write everything down, but most “normal” mechanics I know are not as inclined to do so (I’m a systems administrator, working on bikes as a hobby). So even in my city, even though colleagues know about my website, I get a call from time to time about certain combinations – “just to check with you if it would work”. 🙂

      Wouldn’t blame the mechanics – it’s the industry, the manufacturers, that is making things as difficult as possible.
      With the discontinuing of good quality older stuff, as you mentioned – practically forcing us to “shut up and buy newest stuff”.
      I find that unreasonable, not very eco-friendly, and probably not very good for the industry in the long run. As a mechanic, for bottom brackets alone, one needs about 10 different tools now. Same complications face home mechanics, in case they get a new bicycle, or have more than one bicycle, from different eras. Training staff at shops also takes a lot more time, because of a huge number of different, incompatible parts. It seems to be getting worse every year.

      Anyway – sorry for the long rant/explanation – the bottom line is, it’s normal, in my opinion, even for good and competent mechanics, to not know everything.

  2. @Relja, so based on the compatibility information you provided, my bikes that run Shimano Dura Ace 7900 10-speed and 105 5700 10-speed shifters would work with the older Dura Ace 7700 9-speed rear derailleur?

    Reply
    • That’s what think as well.
      The total number of permutations is huge (all the RD models times all the shifters times the number of rear cog combos).
      Si no way for me to test and confirm every possible combination.
      Which is why I noted all the pull ratios – so I too can easily see what matches with what (even when there is a slight mismatch, it’s often worth a try). In the combo you mentioned it is a 100% match for all I know and I’d give it a go.
      In other words, I’m yet to find a combo that should work by my charts, and doesn’t work in practice – if I do, will make sure to correct the provided info.

  3. Hi there
    I am converting a road bike to hybrid. So looking for a 9 or 10 speed twistgrip shifter that will work with a Shimano Ultegra road bike derailleur. I know something like the Shimano SL R770 thumb shifter is widely recommended but I specifically want a twist shift. Is this possible? Thanks.

    Reply
    • This should work with Shimano Ultegra rear derailleur, unless it’s an 11 speed one (so, works with 10, 9, 8…):
      Grip Shift 3×9 Shimano compatible shifters
      (Amazon affiliate link)

      Haven’t tried that particular model, but it’s what I could Google that is grip shift, and works with Shimano RDs.

      SRAM grip shifters are more widespread, but most would require a compatible (SRAM) rear derailleur.

    • If it is in fact 2:1 (the Shimano compatible), then it will work with all the Shimano rear derialleurs for 9 and fewer speeds, as well as with 10 speed Shimano road derailleurs, except Tiagra 4700.

  4. Running campy 10’s shifters with 11’s shimano der. & 9’s Shimano cassette
    Works spot on, This would make derialleur more like 1.5 ratio ??
    as I agree with pull ratio average

    Reply
    • Or the shifter cable pull is not (completely) accurately measured.
      Also, for Campagnolo 10 speed shifters, cable pull differs along the stroke – increasing as the gears are changed towards the larger sprockets.
      I’m not able to measure 100% accurately, and tell whether it is similar with Shimano as well.
      The fact that manufacturers don’t publish the data isn’t helping either.

      Might find this discussion interesting:
      Rear shifter compatibility discussion

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