• Achtung, achtung!  :)

    During July 27th 2024 (or 28th, depending on your time zone), hosting server maintenance is planned and the forum will not work normally (we'll set it to read-only mode at best, though it will be completely offline for a while). Hopefully, it will all go well and we will be back on line within less than 8 hours.

    Thank you in advance for your patience.

    Note, this has nothing to do with the planned forum upgrade to version 2.3, which will most probably happen at a later date (probably in Autumn).


Front derailleurs explained - article comments

Not open for further replies.


Wheel Wizard
Staff member
To prevent article pages from being miles long, but preserve all the useful questions and answers provided over time, I've decided to copy/paste the website comments to the forum - and "move" further discussions here.

These are the comments from the article:
Front derailleurs explained

This topic is closed for further replies.

If you can't find the answer to your question in this thread, please open a separate thread with your question/problem, in an appropriate forum section (this is the Drivetrain section).

Last edited:
  1. spook
    27/06/2019 at 16:31
    Good Stuff for a newb like me attempting to work a sram xx grip shifter (2×10) with a deore FD. There appears to be a lot of fuzz around this topic. Appreciate the straight line intel, the mud is clearing.
  2. 504f2dc6badf1813b1c1b06655ebd312.jpg

    02/07/2019 at 23:35
    will shimano cx70 front derailer work on triple, running 44/34/24 front and12/34 rear
  3. dea31a43b2f405be5547e2de6beb5ba9.jpg

    Reinhold James Weick
    29/05/2020 at 14:21
    thanks for explaining top and bottom pull … I’m working on setting up a derailleur now that can be configured as both … and it was mystery as to why there were cable grooves on the damn thing that were not being used …
  4. d9449e5202cc4c261162eeef83e28f8c.jpg

    Leandro G
    08/05/2021 at 18:07
    Hi Relja,
    I want to change my 36/22 crankset (i don´t like the big 14t jump) to a 36/24 or even 36/26, my derrailleur has 14t capacity (Shimano FD-M4020).
    Do you think the new setup could work well? Or probably i should couple a 36/26 Fc-M4100 with a FD-M4100-M derailleur (10t capacity)
    • 3fd0d771d754ced79ca6b702635900b5.jpg

      09/05/2021 at 06:39
      Hi Leandro,
      I don’t think that the FD would mind if the tooth difference is reduced.
      Problems could occur if you did the vice-versa thing: using a 10T capacity FD for a 14T chainring size difference.
      But using a 14T capacity FD with a 10T chainring size difference should be fine.
      I’m doing almost the exact thing on my road bike (using 53-42 cranks, with a FD designed to work with 53-39 cranks).
  5. 54fcfc6b5f0df4a6507a844a672cdd18.jpg

    03/09/2021 at 00:42
    Hi Relja,
    I have come across your page while looking for info to rebuild the drivetrain of my bike. It is impresive the amount of material you have uploaded. It will take some weeks to review all the contents. Thanks a lot!
    My issue now 🙂
    Due to my mtb frame characteristics I have been looking for a FD with top pull and low clamp. The dual pull options I have tried were high clamp (Shimano SLX FD-M7025-11 2-/11-speed) and the guiding towards the FD was akward and mechanically poor due to the cable stop orientation. No trace of top pull, low clamp available out there. Result: I gave up the 2×11 idea
    Next target is 2×10 so I have scanned the whole Internet looking for a low clamp, top pull FD. I managed to find a model that it is still in stock (Shimano SLX FD-M675). “Problem”: Vendor information states that the FD largest chainring is 40/38 teeth, while I was planning a 36/26. I contacted Shimano but they stick to the official speech, of course! 😀
    What’s your opinion on using this FD Shimano SLX FD-M675 with a largest chainring of 36 teeth? Will shifting be compromised?
    I have read the info in your site regarding FD and I am aware that the FD-M675 will have a larger curvature than the 36T chainring which could cause some chain rubbing. What are the chances this will occur taking into account the teeth discrepancy is only 2 teeth (38 vs 36).
    Thanks a lot for your help,
    • 3fd0d771d754ced79ca6b702635900b5.jpg

      04/09/2021 at 22:57
      Hi Joaquín,
      You are welcome. 🙂 Yes, I’ve practically written several books online on my websites over the years. Primarily for my own reminder and reference, but it’s great to see they are also helping the others. 🙂
      FD chainring sizes basically affect the curve of the cage. There are two possible mismatches here:
      1. FD is designed for fewer teeth than the chainrings actually have (not the case in your situation)
      In order for the rear part of the FD cage to not hit the largest chainring, FD cage needs to be placed too high, sometimes almost 1 cm above the largest chainring.
      This results in slow and poor shifting.
      2. FD is designed for more teeth than the chainrings have (the case in your situation)
      Depending on the frame’s design, the rear side of the cage could be hitting the chainstays, hence, again, forcing the mounting point to be pushed higher, resulting in poor shifting.
      If that’s not the case, the problem is less severe. You might experience some more chain rub even when not severely cross-chaining. And shifting will still not be perfect, but if the cage can be set to the optimal height (i.e. the bike frame not getting in the way), shifting can be acceptably good.
      Hope this helps.
  1. Joaquín
    05/09/2021 at 14:29
    Thanks for your reply Relja!
    Well, I am coming from a 3x setup with a big 44teeth chainring so I don’t expect the FD hitting the chainring. I am more concerned about rubbing issue and shifting.
    Obviously is try and error but with a cost. The last option would be moving to a 1x setup…. Not my cup of tea but at least I will get rid of the FD burden. Other issues will pop in with 1x (Chainline mainly) but for that I will ask you in the correct thread 😉
    Thanks a lot and congrats for your site!
    Joaquín from Belgium
  2. 8c2fc7c4197cb5e463cfbd365ce11353.jpg

    Allan Morgan
    23/09/2021 at 11:39
    Hi Relja,
    I am trying to work out the difference between the following Shimano front derailleur part numbers. The code extension is either a “3” or a “6”. For example the following codes are from the current Shimano product range but three us no explanation as to the meaning of the extension number. The 3 and 6 extension numbers appear throughout their interchangeability tables.
    Can you help?
    Kind regards
  3. 8d1d5fab801474da7ae1e81d69b2f15d.jpg

    Jim Metcalf
    07/02/2022 at 23:19
    I have a ICE recumbent trike, on which I’ve mounted a mid-drive motor. It has a double chainring that extends outward from the frame more than the prior crankset. The old 3×9 down pull FD is unable to extend out enough to reach the large chainring.
    The normal solution is using a direct mount adapter that extends out the derailleur beyond a standard clamp mount, as typically used used on MTB with fat tires. My problem is finding a compatible front derailleur. I’ve searched the web for hours and can’t seem to find the right one. My lack of knowledge doesn’t help.
    It needs to be down pull. I believe either a double or triple will work with my friction Microshift bar end shifter. My largest chainring is 42, smallest 34.
    Further problem – the 42 doesn’t give me a very high top speed. I’d like to sift to a larger chainring in the 48-52 size if that is possible. I would increase the small chainring accordingly.
    Can you suggest a compatible FD for my situation?
    • 3fd0d771d754ced79ca6b702635900b5.jpg

      08/02/2022 at 20:22
      Hi Jim,
      Several things to consider here for the FD (please correct me if I got something wrong):
      It should preferably be mounted without a clamp, so you can mount it on an adapter and make it “sit” far out enough to reach all the chainrings.
      Since it will require a custom-made mount, I suppose it doesn’t matter if the FD is a direct mount, or the older standard that is fitted onto a brazed-on clamp equivalent.
      I also suppose that swing direction is not important (top swing, bottom swing or side swing should all work).
      The cable should be coming from the bottom (bottom pull).
      Shape should match a chainring of about 50 teeth.
      It should work with double chainring cranks
      Considering all that, I’d go with:
      Shimano Sora FD-R3000-F (Shimano website link)
      That FD is of decent quality yet it doesn’t cost too much. It should easily handle the largest chainring of a size going from 46 to 52 teeth.
      It will also work fine with the smaller chainring being up to 16 teeth smaller (like 48-32, 50-34, 52-36 etc.).
  4. b9f45b2bc805a154f6eb3911a50fd4fc.jpg

    Sean Evill
    20/03/2023 at 09:19
    Hi Ralja
    I am currently running an FD-M618 with a 38/24 and want to run a 40T for a better flat speed. From reading your compatibilty, I cant seem to stop the chain rub in the lower ring on the back of the FD as I need to go high on the frame for it to clear the 40T which lifts the FD to rub on the chain. My question is, what FD should I run to be able to run the 40T and what lower chain ring should i ideally have or will the 24 be okay as its a 16 tooth difference? It also a 2 x 10 speed on a voodoo MTB. Thanks Sean
    • d693f26dcd2fedd28dfc1ad7a66e01a2.jpg

      20/03/2023 at 13:34
      Hi Sean,
      16 T difference generally works fine (allowing you to easily shift from one chainring to the other).
      As for the rubbing – with smaller sized chainrings, and relatively short chainstays of modern bikes, it’s more pronounced.
      Unfortunately, I don’t know which model would work. It boils down to trial and error. The most likely candidate would be a FD designed for ~40 T largest chainring (most modern double MTB FDs are designed for 36 or similar tooth counts).
      Another note: 2 T is not much of a difference for the front chainring (at the rear, 2T makes a lot more difference) in terms of gear ratios. With high-tooth count cassettes available (especially for 9+ speeds), it might make sense to look for 46-30 T cranks (often sold as trekking, or gravel or similar), paired with a matching FD (I saw some Acera class FDs designed for 48 ~ 46 T chainrings).
      42 T FDs were readily available for triple cranks, but I don’t think they would play nicely with modern compact cranks.
      If the chain rub occurs only when severely cross-chained (i.e. using the smallest 3 chainrings of the 10-speed cassette while on the small front chainring), I’d not worry about it, as it isn’t a combination one should generally be riding in.
This topic is closed for further replies.

If you can't find the answer to your question in this thread, please open a separate thread with your question/problem, in an appropriate forum section (this is the Drivetrain section).

Not open for further replies.


Support BikeGremlin

Help BikeGremlin stay online with a Patreon donation:

Top Bottom