Tiagra 4700 STI Rear Mech options

mr_eddy Posts: 830
edited August 2019 in Workshop
Hi All

So I have Tiagra 4700 shifters (the new under the bar routing version) and I am running a single ring 40t chainring with a 11-32 rear cassette (also Tiagra). My rear 4700 mech is really noisy, Its got steadily worse over time.

I am pretty good with the spanners so I have checked all the usual suspects - Firstly I checked that everything was aligned correctly, I even put in a new mech hanger (frame came with a spare), I have checked the indexing, changed the cable, put on a new spare chain (brand new 10 speed Shimano chain), Removed and cleaned/greased the jockey wheels and also removed and re-seated the cassette. I have also tried adjusting the B screw to get the chain closer to the cassette cogs.

As a final test I put I removed the chain, took of the mech and put the chain back on so it was running as a single speed with the chain in the middle of the rear cassette , Took this for a spin and no noise at all (so think its fair to say its not the chain/cassette/hub or chainset).

I also have another bike that is 1x10 so I swapped the cassettes and chains and the noisy mech is still a problem so as far as I can ascertain the issue is the Tiagra rear mech. The noise is different to the noise you would get if your indexing was out its more a general persistent chain noise.

Anyway when riding along when you look down the rear mech seems to vibrate near the lower jockey wheel and when stationary you can feel a fair bit of play in the lower mech assembly (the rear mech is screwed on tight just the lower portion seems 'loose')

Given I ride a lot of gravel I suspect its taken a hit and done some damage so I am looking to replace, My question is what options other than another 4700 rear mech do I have? If I am commited to a new rear mech then it would be good to get one that can handle a 11-36 or maybe something that has a clutch?

I know the 4700 has different pull ratios to other 10 speed stuff so I think 10 speed XT is out any other ideas or am I going to have to go 4700 again - I am slightly dubious as my current 4700 rear mech does seem quite flimsy


  • mr_eddy
    mr_eddy Posts: 830
    Think I have just found the answer - Shimano GRX the new gravel specific stuff, The 10 speed rear mech is listed on Shimano website as 'compatible with current 10 speed dual control lever', Comes with clutch and can take up to 40t out back so just need to see how much one of these is.
  • keef66
    keef66 Posts: 13,123
    You could try an 11 speed RD because they use the same cable pull. So 5800 / 6800, or newer R7000 / R8000 if you want the Shadow geometry etc. I suppose the cage plates might be marginally closer together so you may need to run an 11 speed chain.

    The new Ultegra RX800 has a clutch and the medium cage takes a 34t officially so probably a 36t in practice.
  • mr_eddy
    mr_eddy Posts: 830
    Update - Went with a GRX RX400 (10 speed specific) and its designed to work with 'current 10 speed road systems' (read Tiagra 4700). Anyway bolted on and after a bit of adjustment works well. A bit more friction from the chain but I put that down to the clutch (which I can turn off on road sections).

    It was not that cheap at £45 but I reckon its worth it - I also have the added advantage of now being able to go up to 36t - The box says the RX400 officially supports 36t (May even work with 38t).
  • rk.mail
    rk.mail Posts: 6
    edited November 2019
    A few days ago, I also installed 11-32 Cassette and fitted a new 10-speed chain. It’s a Tiagra 4700 equipped bike, although the Chainset is 105 R7000. I started to have noise and vibration in the drivetrain. This issue occurs on the 4th and 5th largest sprockets primarily, but not on the outward sprockets of the cassette. Looking closely, when guided to the cassette by the RD the chain moves 'in place' twice every revelation. The Cassette has some bold teeth, which catch the chain, but 1/8 of a turn later, the chain moves into place so that it is seated perfectly between teeth. This tiny bit of movement of the chain to the bottom between teeth makes a knocking noise - and you can feel it through the Chainset. The bold teeth I was talking about that seem to cause the chain to be catched midair, are the last teeth before the longest spikey teeth. Anyway.

    My assumption is, that this is caused by the RD-4700 and the following fact regarding the 11-32 cassettes. The Teeth in the middle segment of the 11-32 cassette are one tooth larger than on the standard 12-28. This specific sprocket size, primarily 4th and 5th largest sprockets, results in an imperfect distance between RD and Cassette sprockets. I think the RD cannot handle the cog sizes in the middle segment of the 11-32 cassette. Maybe it is only occurring at the exact chain length I got right now. Maybe it’s an issue with the spring tension of the RD-4700 more specific its movement behavior.

    I am looking for some opinions. I am relatively new to road bikes, so I can't judge how good my theory regarding this issue is. And maybe someone else experienced problems with 11-32 and 4700 Groupset.
  • Update - Under load this issue is probably no issue. I made my assumption while the wheel was free. But when I apply some load via brakes or by gently holding the wheel while pedaling, the noise seems to not appear.

    Strangely though, on my first test ride I felt the vibration in my feet through the Chainset. I was looking for the reason. Meanwhile I also adjusted my derailleur hanger.
  • rk.mail
    rk.mail Posts: 6
    edited November 2019
    Upped the same post twice. Deleted.
  • Update - Still didn't test ride regarding the issue above. But another problem appeared. The derailleur positions don't line up with all the cogs of this cassette. When I look at how the chain is positioned on the sprockets, I see that the chain is moving further and further towards the rear wheel when shifting to bigger sprockets. When I compare the 11-32 cassette to the 12-28 cassette I was using before, there are more 'spider type' spacers used in the 11-32 cassette. Where the 12-28 has only one 'spider type' spacer, the 11-32 has tree.

    Again, making an assumption here, maybe the 'spider type' spacers are thinner compared to the spacers used in the mid-section of the cassette.

    I can't get the shifting on the smallest cogs right without causing some rattling at the biggest cogs. This seems like an cable pull issue but 4700 shifters and 4700 derailleur are used. What is wrong about pairing 4700 with HG500 11-32 cassette. It seems to not work quite right. I don't get it.
  • Update - When I am not cross-chaining the shifting seems okay. Anyway, I have to adjust the barrel adjuster exactly to a fraction of a turn to get the shifting to a normal level. This clearly changed after installing the 11-32 cassette.
  • Update - Drives and shifts like a dream. Actually nice that it requires some work but you get rewarded at the end. Hopefully the Rear Derailleur doesn't need to be adjusted frequently.