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Got a (heavy) plastic bag stuck in my rear derailleur of my <1 year old Salsa Journeyman Apex 1, the bag fully wrapped into the derailleur wheels while I was biking at about 10-15 mph. I had to take the whole derailleur apart to remove it.

Ever since it has not shifted well (no matter how many times I index it) and it has significant vibration in the 6th gear (no others which is odd). I've taken everything apart and cleaned it thoroughly, double checked to make sure it was put back together correctly, replaced the derailleur hanger (although it didn't really seem bent) and triple checked to make sure the chain wasn't worn (bike has around 1k miles so didn't think it was and it was not).

When I look down it looks like the derailleur is bent slightly inwards, could the derailleur itself have bent? Should I just purchase a new one as it seems to be the last possible variable in the equation and Apex 1x11s are around $70. Seems to be what a shop might charge to diagnose and fix this (plus I need to wait for at least a month to get to a shop.

Any help is appreciated.

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    When I'm repairing a bike with a wonky derailer the first thing I usually do is remove the derailer and install an axle (dunno what size -- I just rummage thru the spare parts until I find one that fits). Before placing the axle I install a nut on it so that I can tighten that down after it's in place. Then the axle gives you a very accurate view of how well aligned the hanger is, and, if not perfect, you can slip a length of pipe over the axle to bend and straighten the hanger.
    – Daniel R Hicks
    Commented Apr 7, 2020 at 0:26
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    @DanielRHicks It's M10x1. That's a good trick. The same thing could be done with a long M10 screw and nut from the hardware store.
    – Nathan Knutson
    Commented Apr 7, 2020 at 0:31

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It is entirely possible the derailleur is bent. In shops the usual order of operations when something appears tweaked back there is to address the hanger alignment first, and then if the derailleur is still misaligned to assume that it itself is tweaked. Usually you can see it when holding the bare derailleur and sighting the mounting surface versus the cage (they should be parallel), but it can be subtle.

However, the step that hasn't been done here is taking a derailleur alignment tool to the new hanger and corroborating that it actually is in perfect alignment. Some sources say or imply that a new hanger is an automatic cure-all, but that's not necessarily true, especially because 11-speed really has almost no tolerance to imperfect hanger alignment. Some correction may be needed even when it's new. That said, if it's the same misalignment as was present before, that makes this being the problem less likely.

Bending things back manually to get you by in lieu of a shop, a new derailleur, or an alignment tool can sometimes be successful.

A no-special-tools hanger alignment consists of poking a 5mm wrench (3-way wrenches work well for this) into the pivot bolt and giving it the business. Sighting the parallelism between the guide pulley and the smallest cog can be helpful. Were you to do this, I'd do it with your old hanger because it's more sacrificial. Remember that you're working in all the directions, not just up and down.

One can attempt to use the same method to compensate for a slightly bent derailleur, again just reefing until things look parallel.

Sometimes with derailleurs the bend itself is all in the cage and can be manually worked out to some extent, although on a skeletonized aluminum cage like this, that's less likely to work.

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First thing that comes to minds is: did you put the jockey wheels back in the cage in the correct positions. The upper and lower wheels are different (the top one has some lateral play) and have a correct direction of rotation.

I would not have thought the derailleur would bend before the hanger. At least not the main body and parallelogram. The cage may be more susceptible.

I'd also check the cassette has not come loose on the freehub body.

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  • Cassette was removed cleaned and wrenched down to 40nm. And i actually the pulley wheels incorrect the first time i put them back. I cleaned the derailleur again, noticed they weren't facing the right way (fixed them) and was positive that was going to be the fix but unfortunately it hasn't solved anything
    – Bobbygllh
    Commented Apr 7, 2020 at 0:32
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I had some plastic doggie bags fall from my rear pocket, land on the lower chain run, and get swept into the derailleur. For me the B stop lug bent, allowing the whole unit to rotate too far and dropped the chain tension to quite slack levels.

I suggest you contrive a way to hang your bike up, and get down close to the transmission. Slow-pedal with your right hand, and explore more, though be careful there are a lot of moving pinch hazards down here when the chain is moving.

Try pushing your rear mech and see where there is play. Any number of linkages and swivels could have minor play, that adds up to the symptoms you're seeing.

A replacement mech is your ultimate fix, that's what I had to do.

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  • Slightly fudgy here - mine was a chain tensioner for an alfine IGH, and so it has no sideways motion. However the general layout and specifically the chain route are the same as a normal multigeared bike.
    – Criggie ♦
    Commented Apr 7, 2020 at 0:17
  • i've spent at this point hours listening to it and trying to figure out whats causing the vibration but haven't been able to
    – Bobbygllh
    Commented Apr 7, 2020 at 0:34

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