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Bicycle front derailleur compatibility. Which FD can work with which shifter, crank (chainrings), frame mounts, chains...

Compatibility [05] Front derailleurs

Updated: 27/09/2019.

This post explains bicycle front derailleur compatibility of various makes and models. For a detailed explanation of front derailleur (FD in the rest of this post) mounting systems, cable routing and capacity, read this article: Front derailleur.

FDs differ in several categories (they are all explained with pictures in above linked FD article):

  1. Mounting: braze on, clamp mounted, or direct mounted
  2. Cable routing: top pull, bottom pull, or bidirectional pull (double pull)
  3. Big front chainring teeth number that FD is designed for and mounting angle
  4. Number of front chainrings: double vs triple
  5. FD cage rotation relative to the clamp position: high clamp, low clamp, or the new Shimano side-swing
  6. MTB vs Road FD
  7. Number of speeds (number of rear sprockets and chain width) FD is designed for
  8. Exceptions

1. Mounting

FDs are made for mounting on frame fixed braze on, or come with clamps for mounting on the seat tube. If FD comes with a clamp, seat tube diameter must match the clamp diameter. A newer standard, used on mountain bikes is the direct mount, it is explained at the end of this chapter.

If a frame comes with a brazed on FD mount, in order to mount a clamp on FD, the frame mount must be removed (cut off). In some (rare) cases the clamp can be put above/below the frame mount, so it can stay, as long as it doesn’t interfere with FD movement and proper mounting relative to the front chainrings.

Frame with a front derailleur braze on holder.
Frame with a front derailleur braze on holder.

Standard clamp (and seat tube) sizes are:
1 1/8″ (28.6 mm)
1 1/4″ (31.8 mm) and
1 3/8″ (34.9 mm)

If a FD is a braze on type and the frame doesn’t have a FD hanger (or the frame hanger is too low/high for the size of front chainrings used), a separate clamp can be bought so that FD can be fixed to it. This is a much more universal type of FD.

Front derailleur clamp. It is used when a braze on front derailleur needs to be mounted on a frame without derailleur holders.
Front derailleur clamp.
It is used when a braze on front derailleur needs to be mounted on a frame without derailleur holders.

Direct mount FDs can often be fitted to a frame without direct mount attachment holes using an adapter, enabling the FD to be secured by a (threaded) BB shell. There are also adapters for frames with a round seat tube cross section of a standard width, so that a direct mount FD can be attached to them.

Frames with exotic seat tubes (either by cross section that isn’t round, or by diameter that varies from the three standar sizes), often have FD mounts made on the frame. If, for any reason, those mounts can’t be used (damaged, or not fitting the FD at hand), an adapter can be used – held in place by the BB shell – for frames with a threaded BB at least.

2. Cable routing

There are FDs that have a cable attached from below, from above, or from any of the two. Frames usually have only one type of cable routing.

Double pull FD. Enables routing from either side. Here, two cables are routed, from the top and from the bottom. Of course, only one cable is mounted in real life - either from the top, or from the bottom. Never two! :)
Double pull FD.
Enables routing from either side. Here, two cables are routed, from the top and from the bottom. Of course, only one cable is mounted in real life – either from the top, or from the bottom. Never two! πŸ™‚

With double routed FDs this isn’t important, but for the other models, if the FD’s cable routing doesn’t match the frame design, there is a special adapter that can reverse the cable direction.

FD cable routing adapter. Enables reversal of cable routing to the front derailleur.
FD cable routing adapter.
Enables reversal of cable routing to the front derailleur.

In the picture above, the frame has cable routing so that FD cable comes from above. FD is designed for bottom cable routing. The adapter with a wheel onto which the cable is placed is mounted on the seat tube below the FD, so that the cable can go over it and up to the FD. Everyone is happy. πŸ™‚

Almost all the road FDs have bottom pull cable routing, while most MTB FDs have either top, or dual cable pull. 

3. Teeth number (the size) of the largest front chainring a)
and mounting angle b)

a) teeth number

FD is curved in order to align with the curve of the largest front chainring. A typical MTB chainring has 42 teeth, while road bike chainrings often come with 53 teeth. A smaller chainring requires the FD to have a much more curve in order to align (and vice versa).

Well placed FD that perfectly aligns with the chainring shape.
Well placed FD that perfectly aligns with the chainring curve.

Imagine in the picture above that the FD cage is shaped to match the middle chainring. It would have to be mounted either too high, or it’s rear part would bump into the big chainring, since it has too sharp a curve.

FDs are usually made to match chainrings with 42, 48, 50, or 53 teeth. If FD and large chainring are mismatched for a couple of teeth, there’s no problems, it’s close enough. If, however, a difference is large, the following problems occur:

  • Chainring has a lot more teeth than the FD is designed for: like explained above. FD will have to be mounted too high, which will make shifting slow, poor and might cause chain rub on the rear lowest part of the FD after shifting onto the smallest chainring.
  • Chainring has a lot less teeth than the FD is designed for: front part of FD will be correctly positioned, while the rear part of the cage will remain high up, and the chainring curves sharply down. It will not align. This will not hurt shifting, but will cause a lot of chain rub on the FD cage – as soon as some shifting gears in the rear sprockets causes minimal amount of cross chaining.

b) mounting angle

Seat tube angle (onto which FD is mounted) is usually about 70 degrees for road bikes, while MTBs usually have a bit steeper seat tubes, around 65 degrees. If a FD designed for more vertical tube is mounted on a tube that has a lot steeper angle, the effect will be similar to that of placing a smaller chainring designed FD on a lot bigger chainring. And vice versa.

A FD designed for a lot steeper tube is put on a more vertical one. The rear part of the cage is too high, even though FD is mounted at the correct height.
A FD designed for a lot steeper tube is put on a more vertical one.
The rear part of the cage is too high, even though FD is mounted at the correct height.

Similar problems can occur if the mounting position isn’t correct – happens on some special, or custom built frames.

A frame on which, because of the low rear axle, FD must be placed a bit behind the seat tube. A specific case.
A frame on which, because of the low rear axle, FD must be placed a bit behind the seat tube.
A specific case.

If a FD is a braze on mounted type, this can be corrected with made adapters:

Adapter for changing FD angle to a steeper one and for moving it to the rear.
Adapter for changing FD angle to a steeper one and for moving it to the rear.

4. Double vs triple

FDs are made in two variants: for double and for triple front chainrings.

Double vs triple FD
Double vs triple FD

Double FD will work with a triple chainring if the difference in teeth number between the smallest and the largest chainring is rather small (which defeats the purpose of a triple chainring though). For example a 34-42-48 chainring. Also, if the operation (movement) of the FD is limited to the two largest chainrings, it can work OK.

Triple FD will work on a double chainring if the difference in teeth number between the chainrings isn’t bigger than 12. One can “get away” with 14 as well, but the lower difference, the better.

Compact cranksets, with two chainrings that vastly differ in size (usually 34-50 combination) will work well only with double FDs with the curve appropriate for the big ring size (50 to 52). Even when using a double FD, it is best to keep the tooth cound difference up to 16 (like with 34-50, or 36-52 chainring combinations).

5. High clamp, low clamp, or side-swing

With older standard for FDs, the cage is below the mount, so that FD cage swings below the FD body. These are the high clamp FDs. Low clamp is a newer Shimano system meant for MTBs with rear suspension. FD cage is practically in line with the mount. This leaves more room for mounting the rear suspension to the seat tube. Previously used terms for this were bottom swing (for high clamp) and top swing (for low clamp), but with the introduction of Shimano side-swing system (explained at the end of this chapter), these terms are no longer precise enough.

If the bike has no rear suspension, or there is enough room for a standard FD below the suspension, it is irrelevant which type of FD is mounted (as long as it’s suitable in terms of other explained criteria – angle, size etc.).

The newest Shimano system is the side-swing, where the cage rotates sideways. These FDs can be clamped with a high clamp, low clamp, or using a direct mount system.

Shimano Side-Swing front derailleur
Shimano Side-Swing front derailleur

6. MTB vs road FD

Shimano road and MTB FDs have different cable pull ratio – that is the amount of FD movement for each mm of cable movement. This means that MTB FDs might not work well with indexed road shifters and vice versa.

With double chainrings, this issue can be fixed with adjusting limit screws and it could be made to work. With triple chainrings, it is harder to get it to work properly. However, FD cage is a lot wider than the chain and triple FDs have just 3 positions, so depending on particular shifter – FD combination, even that can sometimes be made to work OK.

Having said all this and in spite of officially different cable pull, all the FDs almost always work OK with all the shifters, regardless whether it is road, or MTB. Exception are the Shimano 11 speed road FDs and Shimano Tiagra 4700 10 speed FDs – they have a (vastly) different cable pull (and cable anchor arm), so they are not compatible. So, while this will not shift perfectly, especially with triples, it is worth giving a try and seeing if it’s good enough for one’s criteria – if what one has on hand are mismatched road and mtb shifters and FDs. If it doesn’t work satisfactory, the cheaper option is to find a FD that matches the shifter.

7. Number of speeds

The last AND the least important.  πŸ™‚

FDs are made for a certain number of speeds, i.e. number of rear sprockets. The more speeds, the narrower the chain. There are FDs for 6 to 8 speeds, then for 9, 10 and 11 speeds. Cage width is made to match the planned chain width.

FDs for 9 (left) and 10 speeds (right)
FDs for 9 (left)
and 10 speeds (right)

However, since the chain moves left-right on the rear sprockets, FD cage is a lot wider than the chain. That is why it is possible to mount a 10 speed FD and use it with a 6 to 8 speed chain.

FDs are very forgiving in terms of speed number (even in terms of manufacturers), so they can be mixed and matched. One of the few pieces of equipment where it is possible to change a Campagnolo 10 speed with a Shimano 8 speed and it all works.

When a FD for more speeds is put on a chain for fewer speeds, the only bad effect is more chain rub. Since the FD cage is narrower, smaller angling of the chain (when changing gears at the back) will cause it to rub the FD cage. With indexed shifters, a trimming option can help, while with friction shifters this is not an issue.

8. Exceptions

Exception to this rule are Shimano 11 speed road FDs. They will not work very well with anything but Shimano 11 speed road shifters and Shimano Tiagra 4700 10 speed road shifters. Same goes for Tiagra 4700 FDs. Newest Campagnolo 11 speed system: Revolution 11+ (older one is Revolution 11) also requires matching (Revolution 11+) shifters and derailleurs. The reason for incompatibility lies in different cable attachment and amount of needed cable pull per gear change. Why was something that had already worked “fixed” has probably more to do with the marketing, than with the engineering department of the company.

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

Related post – Front derailleur:

Bicycle front derailleur (FD). Types of front derailleurs, frame mount standards, FD compatibility...
Bicycle front derailleur (FD). Types of front derailleurs, frame mount standards, FD compatibility…

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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22 thoughts on “Compatibility [05] Front derailleurs”

  1. Hi I just broke my cx70 on my CX bike so need a new top pull front deraulier with 31.8mm clamp but as metioned above a new cx70 is hard to obtain now.

    I have 105 STI 5700 shifters

    A run an altus mtb rear mech and it works perfect, this made me think try a mtb front mech also.

    48t big ring 34t small ring double 110bcd road crank.

    Read else where online that a XTR mtb front one may work for cx but there a a multitude of models, any advice what models of FD to try?

    How about:



    • I live in a country that is war/crisis torn and impoverished. So getting proper parts is often difficult – both because they aren’t available, as well as because of the price. Hence – I would try with whatever is at hand (old spare parts, trashed donor bikes etc.). FD-s aren’t too picky, especially if handled properly, with friction shifters. πŸ™‚
      The point of this is that what I would do (and perhaps recommend) might not be the optimal choice for everyone. Now to the question at hand – what are the options?

      If in a position to order a new part, I would use what’s the most optimal choice.
      FD you linked is for 66 to 69 degrees chainstay angle (which is the angle between the seat tube and the chainstay).
      While most road FD-s are for 61 to 66 degrees chainstay angle.

      So that would be a deciding factor for me. To choose one that fits the bike best.

      As for compatibility – most Shimano road double FD-s are designed for 52 to 46 largest chainring, and can handle 34 toothed small chainring. The up-to 10 speed ones (apart from Tiagra 4700 FD-s) should work perfectly fine. There is no reason to go with an MTB FD if you already have road shifters – unless it matches your frame better.

      If the angle is over 66 degrees – the FD you linked should be OK.
      If the angle is 66 degrees, or smaller, I’d go with 10 speed 105 FD (5700 series, or older), or, if on a tighter budget, Sora 9 speed one:

  2. Hi Relja, When I looked on the map, I realized I was most likely passing by your shop during my many visits of my friends in NS. Well, next time I will stop by πŸ™‚

    I would like to ask you few questions:

    I am riding 3×9 XT set on my 2009 GIANT Reign X0 (my old reliable friend). Now, the time to change both FD and RD came again, but this time I can not find 3×9 XT in the stores here (Slovakia) anymore. BTW: My Crankset is 42-32-22.
    The only options I found here for FD is 3×11:
    XT FD-M8000 pre 3Γ—11 Side-swing. I can lead the cabe to the FD from the front, so that is fine and according to what you said 3×11 should be fine for 3×9 too. The only problem seems to be the 2 mm narrower cage. I kind of hope to find a way to make it +2mm wider…. ?

    More importantly:
    I would like to get a cassette with 40T (or max 42T). https://tinyurl.com/y6hnto85
    But the only 9sp RD I foud still available is XT M772GS. I was trying to find the SGS model, but no succes. According to the official document the 772 RD can handle max 34T. Is there any solution to this?

    I was also considering to change to 10sp instead, but than I realized, that I will probably face the same problem as with 9sp – According to the official document the 10sp RD can handle max 34T. So I thought to use 11sp RD with 10sp shifter – but from your other article I realized it wont work either.
    Full 11sp, seems to me to much and to expensive…. and I would like to keep the 3-crank in the front.

    Is there a way to make the cage of the new FDs little wider? Would it be better to keep looking for original 3×9 FD?
    What do you think about the 9×3 or 10×3 with 40T option?
    Would you please have any other suggestion?

    • Hi,

      There’s my phone number on website contact info, so even if I’m not at the shop, feel free to contact me (Viber, WhatsApp, call, SMS…) when you’re in the neighbourhood. πŸ™‚

      – Front derailleur –
      I would rather choose a lower end model (or, to be more precise, a “less top-end model”), like Deore, or Alivio, instead of buying an “11-speed” XT.
      Narrower cage will cause the chain to rub a bit sooner, when cross-chaining. So, for example, when on the big up front, now you might get away with no chain rub except when on the largest sprocket at the back. But with a narrower FD cage, you can expect to get some rubbing even when on the 2nd largest sprocket, or even the 3rd. Such cross chaining (big up front – 3rd largest at the rear) is not considered as “severe cross-chaining” by today’s standards, even though it’s not a perfect/very good combo.
      However, apart from that, I wouldn’t expect any more serious problems with the narrower chain. Though I’d still go with cheaper, quite good and durable Deore FD, preferably for 9, or 10 speeds.

      – Rear derailleur –

      Short answer:
      WolfTooth, or similar product sold by a less known (Chinese) brand can help. You can see it here:
      Video showing it installed on an 11-speed bicycle
      Video description has a link to on-line store, showing what the product looks like (though I would encourage shopping and supporting local bicycle stores).

      Longer answer:
      Shimano is often quite conservative when noting derailleur limits. So, for example, Shimano Alivio RD-M3100-SGS has the limit of 36 teeth (with a total chain-wrap capacity of 45 teeth).
      Depending on your frame’s current RD hanger design, if you screw in the B screw (almost) all the way in, you might see it nicely going over the 40 T chainring. 42 would be pushing it a bit too much, requiring the RD hanger extension (noted in the “Short answer”).

      There’s also a “trick” of screwing the B-screw the other way round, so its head is facing the RD hanger, making it push the RD even further, but I think that’s a bit more likely to bend the screw, or damage the small “lip” on the RD hanger that the screw hits into, pushing the derailleur. Similar goes for replacing the B-screw for a longer one (I think it’s an M3, or an M4 screw, would have to measure and check to be sure).

      “Philosophy” answer:
      I fail to see the point of having more than 34 teeth at the back, with a 22 T smallest front chainring. Even for muddy riding conditions, or loaded touring.
      So would advise giving a 34 teeth a try, if you haven’t already and found it not low enough gearing.

      As far as 3×10 goes, I prefer 3×7 with friction shifters: it’s super cheap, super durable, can use practically any modern multi-speed chain (tried from 6 to 10 speed chains on such setup so far, all worked fine). Good 2nd hand Shimano friction shifters, the ones made of steel/aluminium are practically indestructible, and very reliable. 7 and 8 speed chains are much cheaper. Same goes for 7-speed cassettes – cheaper, and there are 11-34 and 12-34 options available. And, with some spacers improvised from any old cassette, they fit 8-9-10-11 speed Shimano MTB freehubs (and road freehubs as well). Video explanation of 7-speed cassette on an 8-9-10-11 speed freehub.


    • THANK YOU, Relja. I am clear now: I would keep all the components in my set as they should be – 3×9. The only think now is the cassette – i will grab either Deore CS-HG400 11-36T or Sunrace CS-M980 11-40T. I also found the clamp to make the RD bit longer: https://tinyurl.com/y3lpbzgz just in case the simple RD tunning would not help…

      I am using the 11-34T XT cassette, I remember when I installed my first 34T cassette I could noticed the difference from previous 11-32Ts – most of my trips are in the forest with quite steep hills. I do not know of anyone using 40T cassette on 22T crank, so I do not know how this would work, neither I know if the 36T would bring the desired effect. So both will be a kind of blind shots…

      AND, thank you for you invitation. πŸ˜‰

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