CityCyclingEdinburgh Forum » Questions/Support/Help

Front derailleur mech rubbing chain--normal?

(9 posts)
  • Started 1 year ago by the canuck
  • Latest reply from the canuck
  • This topic is resolved

  1. the canuck
    Member

    After a very long debacle of supply chain issues, I finally got the mech replaced on my front derailleur (3 wheels), and the correct 9-wheel rear derailleur.
    A screw had fallen out of the front mech, so it wasn't properly lifting the chain from the middle gear to the larger.

    now, whenever I'm in the top gear on the front, unless i'm in the bottom 3 at the back, the chain rubs against the chain guard. Like, fairly loudly.
    The mechanic said it was normal for rubbing at the extreme gears--so, the outer most ones.
    I have no memory of ever hearing the chain rub until the screw fell out.

    Is nostalgia fooling me, or is a mechanic trying to cover for a rushed job?

    Posted 1 year ago #

  2. gembo
    Member

    Does it rub when in the small ring at front and the small rings at the back?

    Posted 1 year ago #

  3. chdot
    Admin

    Mmm

    Shouldn’t rub - generally speaking.

    Might do on ‘extremes’ - large to large or small to small, but shouldn’t use anyway.

    Very short chainstays (racing bike) might cause issues.

    But likely inappropriate front mech - designed for a double ringed chainset.

    OR badly adjusted.

    What equipment - mechs and shifters?

    Posted 1 year ago #

  4. the canuck
    Member

    It's a 27 speed.

    It only rubs when on the large ring at the front, while also on one of the numbers 4-9 on the shift lever, which, if memory serves, are the 6 smallest in the back, and the farthest the axle.

    My vote is badly adjusted because I was there when the mech was selected and it was clearly for my type of bike.
    Technically I know how to do this myself, but it takes ages of faffing and equipment I'd have to borrow. And I'd kind of assumed that the person I paid to put the new mech on would set it up properly.

    It's overall part of a trail of unhappy service experiences, which means I may need to find a new repair/service place, just because I now get irritated as soon as I go in. I used to be very happy with the work done. :(
    But first I want the chain to stop rubbing, I just put a new chain on 100 miles ago, don't want another any time soon.

    Posted 1 year ago #

  5. ejstubbs
    Member

    Technically I know how to do this myself, but it takes ... equipment I'd have to borrow.

    I can't recall front mech adjustment requiring anything more than appropriately sized screwdrivers and allen keys when I've done it in the past. Has the world moved on since I went to a 1x chainset?

    Posted 1 year ago #

  6. nobrakes
    Member

    It sounds like either there’s not enough tension in the cable to pull the front mech over or the limit screw needs adjusting to let it move further to the right.

    If you find the limit screw that controls outward movement and it’s jammed up against the derailleur, try loosening it a quarter turn at a time to let the derailleur move out further. Should just be a Phillips screwdriver or small Allen key.

    If you move the limit screw out and it creates a gap between the screw and the derailleur, the cable might need tightened. I usually just put it in the small ring, loosen the cable clamp screw and then pull it hand tight, re-tighten the cable screw to clamp it. You might then need to play with the limit screw at each side of travel but it shouldn’t take more than 10-15 minutes once you’re oriented with what screw acts as a stop at each end.

    Edit - when I say derailleur I mean the front mech.

    Posted 1 year ago #

  7. the canuck
    Member

    It's the screwdriver I'm missing, plus a rig to hold the bike up. One of my shoulders is not reliable, so I'm not up for playing balancing games with the bike.

    I finally have the bike back, and it sounds better, but I haven't ridden it much. The mechanic was of the opinion that if the arm was moved to the right to avoid rubbing, it wouldn't be properly set to lift the chain across all three gear wheels.

    If it does start sounding noisy, I'll ask around some neighbours for a repair stand and get out some youtube videos to refresh my memory.

    Posted 1 year ago #

  8. ejstubbs
    Member

    I don't know where you're based but you'd be welcome to borrow/come and use my repair stand and tools if it were at all geographically convenient - I am in Fairmilehead. I am a retired person so can usually make time for such things to fit with other people's schedules. If you know the make & model of the front mech I can probably find the relevant service docs for it online.

    Posted 1 year ago #

  9. the canuck
    Member

    Aw, thanks! You're the wrong end of town for me, but I'm pretty sure two of my neighbours have repair stands and would either lend them, or be happy for me to come around.

    The chain sounded ok today, but it was a noisy day. I'll keep listening.

    Posted 1 year ago #

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