Rear derailleurs explained - article comments

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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.

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Rear derailleurs explained

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  1. Tim B.
    15/01/2020 at 14:04
    Hi there Relja
    I’m thinking about to upgrade my bike from Claris R2000 8s system to Tiagra 4700 10s starting from the RD and keep the rest.
    But i’m concerned about if the Tiagra 4700 pull ratio will work nice with Claris R2000 shifters and the 8s chain.
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      15/01/2020 at 14:09
      Tiagra 4700 derailleurs will not work nicely with Claris shifters. Goes for both front and the rear.
      What is the current system lacking in order to require “an upgrade”?
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    Tim B.
    15/01/2020 at 14:23
    The whole system still Claris, my thought is to change 8s to 10s in small steps, because here in Brazil buy the complete system is a little expensive.
    I didn’t bought any Tiagra part yet, i would start to do it if you said that Claris shifters and chain could work nice with Tiagra RD.
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      15/01/2020 at 18:04
      Claris is a very good budget groupset. It’s worked for me flawlessly. With dirt-cheap chains and cassettes compared to 10 speed stuff (at least with prices in Serbia).
      Unless really lacking a gear combination in between the existing gears, I wouldn’t consider Tiagra much of an upgrade. Sure – slightly lighter, slightly faster rear shifting, but since I’m not racing – don’t really care.
      Claris works nicely and shifting is very precise. With nicely shaped levers (at least for my hands and taste).
      It is budget, but gets the job done.
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    26/05/2021 at 06:13
    you will see alot of bicycle part makers including specs on most parts,these specs are a guide only but they may still not work on your bike setup,i have even came across incorrect specs on major bike parts,most specs are correct but some are total missprints,if you are doing custom bike building you basically just have to buy and try like we all do,some stuff works out and some does not.dont be worried to try different setups on bikes as home made custom setups often work better than than the factory spec only fail if you dont try.
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    17/07/2021 at 09:39
    Good afternoon!
    I am using a 1X set up. My crank is 34T and my cogs 11T-50T. My chain is 116 links.
    Is this good or bad? Thank you so much.
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    16/11/2021 at 11:31
    Hello Relja,
    Your site is honestly more like a (bicycle) bible! Very nice work (is it too much to say you’re the next Sheldon Brown? haha
    I was wondering if the tech specs of (Shimano) RD’s were set in stone, or more to be considered as guidelines? I have a 6/7 RD-TY300, of which I know will also work on a 9 to 10 speed cassette, yet the tech sheet ( states that max teeth count for the TY-300 is 34T, with a max difference of 20 between low and high.
    The cassette I can get right now (without having to wait eons) is a 11-36T, ie two teeth above max, and a difference of 25T instead of 20T. Will it totally not work, or will it just be a bit more “clunky”. I will be using a friction shifter BTW.
    Thanks in advance!
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      16/11/2021 at 12:02
      Hi Andy,
      A short answer is: it will work, but be careful.
      A longer answer (with a proper explanation):
      There are three things to consider here:
      1) RD compatibility with the cassette and shifter combo
      – that’s fine in this case.
      2) Max. rear sprocket size
      – Shimano is conservative when it comes to this and, in my experience, on a vast majority of bicycles, RDs handle 2 extra teeth with no problems (though this depends on the RD hanger position and design). In other words: I’d give it a shot, but wouldn’t bet my life on it (only up to one beer bets 🙂 ).
      3) Max. chain wrap capacity
      This is usually a correct specification (not a pessimistic/conservative one). There are two paths to choose here:
      a) Leaving the chain long enough to cover the big-big combination – resulting in a chain that’s too long for the RD to wrap the excess in the small-small combination.
      b) Cutting the chain to be short enough for the RD to wrap the excess in the small-small combo, but that means leaving it too short to handle the big-big combo.
      Both options have their pros and cons. I prefer a), and think it’s safer. A detailed explanation of the scenarios with the pros and cons (and pictures) is given in the article:
      Chain length sizing for bicycles with derailleurs
      (Note to self: edit this article to include this link)
      Comparison with Sheldon Brown is very flattering, thank you. 🙂 He’s a role model and an inspiration, I wrote an article on Sheldon Brown’s legacy. Still, without any false modesty, cycling and mechanics was Sheldon’s life. For me, it’s still a hobby, I’m making a living by working with computers and I don’t think I’ll live long enough to get that much knowledge and practical experience as Sheldon had. But yes – this site was envisioned from the start as a cycling encyclopedia (with an idea to make it mobile/smartphone friendly), offering all the info in one place. I regularly use it as a reference and reminder (prefer writing things down to memorizing it all). 🙂
  1. James
    31/01/2022 at 07:37
    Hi Relja,
    What kind of lubrication do you generally use for pulley wheels with steel bearings?
    Thank you for all of the content on your website!
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      31/01/2022 at 08:58
      Hi James,
      You’re welcome. 🙂
      Grease or oil can do the job.
      They both have their downsides.
      Grease offers longer-lasting lubrication (doesn’t have to be re-applied nearly as often), but it attracts a bit more dust and dirt.
      Oil is the opposite – requiring a more frequent re-application but accumulating less dirt.
      For greasing you have to disassemble the cage (freeing one jockey wheel at a time is fine – I’ll make a video on that), clean, lubricate, assemble.
      For applying oil, spray from the sides is good.
      If using grease, the “regular,” “general-purpose” grease is usually of NLGI2 hardness, and I haven’t had any problems with that, though for the application, a softer grease would be a better match (NLGI 1, or even NLGI 0 hardness).
      What I’ve been doing over the past decades has worked fine for me, though I’m sure some (many?) would not recommend it – still, it’s worked fine for me and that’s what I do with my bike(s):
      I disassemble, clean and put some grease, about twice a year.
      In between those “major overhauls,” I wipe off any dirt and dust from the outside (as best as I can) and spray some fine oil lubricant (MOTIP PTFE spray is my lube of choice – but any fine oil should do the job).
      The properties and “quality” of lubricant are of little importance. Regular cleaning and re-application is what makes the difference. Those systems aren’t sealed too well from dirt intrusion and it’s dirt that creates problems, not the lubricant imperfection.
      Having said that, spare jockey wheels (with the bushings) aren’t too expensive, and they are quite durable, even when not maintained properly. So I don’t sweat it too much – the bike(s) should serve me, not the other way round.
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    31/01/2022 at 10:05
    Thanks Relja!
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    12/05/2022 at 12:35
    Which type of mounting is better? Im trying to buy a new bike and im looking for better details
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    19/12/2022 at 10:58
    Hi Relja,just got myself a new rear mech shimano claris 8 speed rd-2000 series short cage,this one has one jockey wheel that has the shimano centeron G-pulley on it just wondering does the G-pully thing make any difference as i cant tell the difference,shimano also says this short cage will run on a 32 rear cog but when i fitted it to the bike i had to turn the B-screw all the way in,i do think this rear mech is at its limit on a rear 28 cog,on a 32 rear cog there is not enough clearance really,have you played with this one at all cheers
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      Relja Novović
      19/12/2022 at 13:11
      Hi Mike,
      I’ve run mid-cage Claris for years with a 34 T sprocket (RD-R-2000 GS cage).
      With an optimal chain length, I’d be surprised to see the short cage version (SS) not work with a 32 T rear sprocket.
      Regarding the clearance: in my experience, for as long as the upper pulley with a chain over it is not contacting the largest sprocket, the clearance is fine. In fact, I find the shifting to be better when the clearance is as small as possible (without causing interference).
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    18/01/2023 at 04:51
    Hello Relja, I have a friend that changed his 3×9 to a 1×10 setup in his 2010 Specialized Enduro bike, used to be an 11-36 cassette, and now he set it up with an 11-50, Shimano m-773 rear derailleur, and 10speed Shimano shifters, not sure which. model, sorry.. he is having shifting issues, he can upshift or downshift precisely but not both… I told him to check the alignment for the derailleur cogs and the cassette cogs but he claims they are all new…cables are new too. He did have to put in some cheap @ss hanger extender that came with the oversize cassette kit and we suspect this might be the culprit… do you have in mind any extender or hanger link like the “goat-link” from Wolf Tooth that may work with this RD and a 50T large cog? I am doing the research for him but have found nothing.
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      18/01/2023 at 10:14
      Hi Sergio,
      Depending on the RD model and its mounting system – that could be the problem. For details on the mounting standards, see my article Rear derailleurs explained. Briefly put:
      • Standard mount RDs can’t be fitted on a direct mount hanger.Direct mount RDs can be fitted on a standard mount hanger if a b-link is used.Direct mount RDs are fitted to direct mount hangers without a b-link (i.e. directly).
      That aside, RD hanger alignment could also be the culprit. Price doesn’t really matter – even an expensive hanger can be bent, and even a cheap one can be straightened at least once (wouldn’t recommend doing it for several times as the risk of it breaking increases). If straightening a RD hanger, do keep a close eye for cracks emerging over the following few months – and replace it if any cracks appear (before it breaks and causes more damage to the RD, wheel or the frame).
      Finally, for Shimano 10-speed MTB shifters, one needs a Shimano 10-speed MTB rear derailleur. If those two don’t match, shifting will not be good. Do check the exact shifter and RD models (it’s either printed or stambed somewhere) to confirm they are both 10-speed MTB models (10-speed road won’t cut it).
      P.S. I think that 1x systems create problems and consider them to be a fad – unless one is a competing, has problems using one hand, or rides in mud so bad that it frequently piles up against their front derailleur causing problems. The simplest solution I would suggest is to just go back to the 3×9 – it’s cheap, reliable and has a great gearing range. If that equipment is still in your friend’s possession that is.
06/10/2023 at 04:59
I am currently running with 3×9 setup. Planning to go 1×11 with shimano m5100. Is it okay if I use slx11 speed shifter? And also
2) shimano m5120 description is that 1×10 or 2×11. Is it okay if If I run it 1×11?
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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).

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