Chain jammed between chainrings

[TheMarlow]

I have a mountain bike I've owned for several years which I relied on for traveling to and from university. In the past few months a problem has developed with the front chainset where, whenever I try to change between the middle chainring and the largest chainring, the chain becomes jammed in between the two chainrings.

I have tried several times to adjust the adjuster screws, which has had some success- however, after two or three successful attempts at changing gear the problem returns.

I don't know what to do- please help!

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I should add that the bicycle in question uses a shimano derailleur gear system.

[dave_sd]

The adjuster screws set the high and low stops so you don't overshift. They don't have anything to do with the middle gears. You probably need to adjust cable tension because the cables will stretch after a while, and you can usually do that by unscrewing the barrel adjuster that's exiting the shifter itself

[AndrewB]

In addition to what dave_sd said, your chain may be wearing and stretching too.

If you don't have a chain measurement tool, any bike store should have one. Takes about 3 seconds to check. But my guess is that if you haven't replaced the chain in several years, you are probably due!

[trevgbb]

You may find 1 or both the chainrings are bent, creating a gap big enough for the chain to fall into, straighten if possible.