I have an old Cannondale road bike with Suntour shifters.

When I shift from the front middle ring to the small inner-most ring, the chain falls into the gap and binds tightly between the two rings. The chain seems to be an appropriate width for the back cassette and there doesn't seem to be anything that I can tighten to close the gap between the two rings (the two are screwed together and seem tightly affixed to one another).

Aside from not using the inner-most ring, I'm at a loss for what to do. Any ideas (aside from a fixie)?

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    Where you said "cogs" I've edited it to "rings" as I think that's what you mean. Please revert if I got it wrong.
    – PeteH
    Commented Jul 15, 2014 at 6:58
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    I ran into a guy who had this problem fairly often. The bike was an old one and had a new rear cluster and narrower chain to match, so the chain would get stuck between the front rings. Easiest way to get it out, as I showed him, was to slightly loosen the top-most chainring bolt. Probably the correct fix would be to install narrower spacers. Commented Jul 15, 2014 at 11:33

4 Answers 4


As I see it, from my experience you may have any one or a combination of the following issues (from most to least likely):

  • You keep on pedalling at force while shifting down. Usually, when you switch from the middle to the smallest ring on the front you are going uphill and you have to keep pedalling just to avoind falling over. Still, you have to significantly reduce the pressure you apply to your pedals while shifting. If this happens often you should try to change gears a bit earlier in the climb when you still have enough momentum to pedal without force for one or two strokes while your chain switches.
  • Your front derailer is not properly adjusted. Over time the adjustment of your derailer may shift a bit due to al the shaking, or due to dirt lodging between parts. It may need readjustment. If you don't know how to do this I would strongly suggest you ask your LBS for help about this.
  • Your rings are old and worn. Your rings have special grooves and notches on the sides. They are not there because they look good or save material or weight. They are there to help your chain catch onto the next ring. If the rings are very old these grooves and notches might be worn away too much. Ask your friendly local LBS what they think about your rings or just compare your rings to those on a newer bike.
  • Your front derailer is old and worn. Over time the different parts of your front derailer are subject to normal wear and tear and everything becomes more loose and you get some play. You can compensate for this a bit by readjusting your derailer, but eventually replacement is the only option.
  • Your chain is incompatible with your rings. You say it looks compatible with the back cassette, but in the past someone might have changed the back cassette to a model that requires a very thin chain that is incompatible with your rings. Possibly to increase the number of cogs in the back cassette (and thus the gear range) without changing the rear wheel. Are back cassette and front rings the same brand? Can you find serial numbers? Can you find anything in the website of the manufacturer? Again, you might want to visit your LBS for help on this.
  • Your chain is old and worn. If you live in a very dry climate and are a master of bike maintenance this might be the problem. But usually a chain is rusty and squeeking years before it is worn too thin.

I had the same problem and it turned out that someone installed the small chain ring the wrong way and this increased the gap. I turned it around and it works perfectly now.


High force gear changes are sometimes the problem. Try to anticipate as you would in a car. Also, is the chain compatible?


Same thing happened to me this week however it was with a practically new KMC chain. I run a Shimano 105 10 speed triple 50/39/30t and whilst cycling up hill I shifted gears and the chain stuck in between the 39 and 30 chain rings. I took a picture as I couldn't believe this could actually happen.

KMC 10 speed chain jammed between two chainrings

Thankfully I was near a garage and asked if they could help as even though I had a multi tool it didn't have a T30 torque head so that I could release the bolts. They totally helped and after saying a huge thanks and promising to bring my car in next time it needed a service I made my way home.

Upon checking on Strava I realised that my current 5703 triple chain rings installed as a full crankset in June 2015 had grinded out well over 15,400 kms to was probably due a change and the wear in the rings probably caused the problem. I usually change my KMC chain every 5,000 kms so I guess 3 chains for every crankset is about the limit. Thankfully I found a new 170mm crankset on Chain Reaction for just over £100. I will be installing this when it arrives as a precaution as I don't want this to happen again as I almost fell off into oncoming traffic when it got jammed.

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