On my smallest rear gear, the chain vibrates pretty noticeably causing it to "smack around" my front derailleur. It also produces a slight clicking noise from the rear of the bike.

I've adjusted the low and high limits on both derailleurs, and I can't seem to get rid of the noise. The only thing I can think of is to bend the front derailleur wider to prevent the chain from smacking it.

  • 3
    Do you mean the chain is rubbing the cage of the front derailleur? As in, it's just rubbing as you pedal? This is normal for small rear cog + small front chainring, and you should avoid this combination.
    – Weiwen Ng
    Oct 29, 2022 at 0:58
  • 1
    Adding to @WeiwenNg’s comment: the small chainring small cog combination creates large angulation in the chainline, which accelerates wear, increases friction, and just does not smoothly pass the chain. Hence, you should avoid that combination.
    – Ted Hohl
    Oct 29, 2022 at 4:09
  • 2
    please add some photos from the RHS (right hand side, the side of the bike the chain is on) of the bike showing clearly the front mech. I suspect its just out of position a little.
    – Criggie
    Oct 29, 2022 at 4:26
  • 1
    Do you have sufficient chain tension? With these kinds of problems it’s always a good idea to put the bike in a bike stand (or hang it up with a string from the saddle) and take a really close look at the drivetrain under slow pedaling. Does the chain mesh properly with the sprocket? Is it properly aligned? Is the rear derailleur bent? Is it rubbing against the front derailleur? These kinds of things.
    – Michael
    Oct 29, 2022 at 10:08
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    @Criggie what is RHS? Oct 29, 2022 at 16:59

1 Answer 1


Something I would look into. Chain tension (or how old the chain is) and chain lubrication/cleanliness. To me, it sounds like there is an offset caused by an old or dirty chain.

  • I'll take a look and see if I can find a tensioner on the rear derailleur today, and come back to you to see if this fixes the issue Oct 29, 2022 at 17:02
  • Chain tension doesn't really have any influence on the front derailleur whilst staying in the same gear, because on the upper side the tension is dominated by pedalling force. (It can have an influence on how the front derailleur shifts, because that involves a change in used chain length, but this is not relevant otherwise.) If chain tension was the problem, you'd probably be having other problems (chain skipping on the rear sprockets or chain getting sucked up the front sprockets and jamming there). Oct 30, 2022 at 17:46
  • There isn't a tensioner for the rear derailleur other than the b screw, and my derailleur hardly engages it. If you mention leftaroundabout's comment, I'll mark it as the answer. Just "@" me when you've added it Oct 31, 2022 at 23:40
  • Here's a link to a highlight in an article you can use: Oct 31, 2022 at 23:44
  • @leftaroundabout true and there could be two separate issues here, merged as one. An offset can be caused by a few things, clicking means chain tension, sprocket alignment, dirt/wear, or rear derailleur. While grinding, especially in the front, is alignment. If all else fails, see your local bike shop.
    – Ty Long
    Nov 5, 2022 at 19:24

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