chain stuck

[streetsmarts]

so while riding home through Shaw last night in the dark my chain came off / got stuck. i got all greasy trying to unstick it and finally got a bus home.

this ..or something similar....has happened several times. my LBS has adjusted the derailleurs recently.

1. should I attempt to fix (meaning undo this mess and put the chain back on) or take to LBS? I do think this time the chain in partly twisted near hangar

2. is it me...or is something wrong with the derailleur, limit screws, hangar, etc?

thanks

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[drevil]

That's called chainsuck. Among other things, it could happen from worn and/or gunky parts.

[streetsmarts]

That's called chainsuck. Among other things, it could happen from worn and/or gunky parts.

Thanks Drevil! I was reading about that this morning and not sure.

I feel like I don't ride nearly as much as some of y'all. and come to think of it, I got a new chain and cassette ... a month ago? strange.

[PeteD]

Dropped your chain, and then kept pedaling.

First solution is to try to not keep pedaling, and shift back into the big ring to see if you can get the chain to jump back onto the chainring. Takes a bit of effort and experience to know if it'll work or you're making the problem worse.

There are several chain drop catchters available out there... I've run the K-Edge on my road bike, but they're not always reliable, and can easily be defeated by worn chains and chainrings, as drdevil pointed out. Usually it's a trailing indicator that you:

1) Need to clean your chain.
2) You might need to replace your chainrings.
3) You might need to replace your chain.
4) You might need to replace your chainrings+chain+cassette.

From the look from your picture, I'd expect at a minimum #1, and #4 being highly probable: Your chainrings look well worn.

[streetsmarts]

More info:
New chain and cassette 9/13/17 (at about 2200 miles of riding)
Maybe 300 miles since then.
Huh.
Wouldn't the shop look at the chain ring at that time to see if it needed to be changed?

Also, riding in the city - and shifting properly, and dropping the chain - I think I need some lessons re this . I do think part of it is operator error. Will google that later!

[Judd]

It's probably from all the wattage you're always putting out.

[EasyRider]

Did it just fall off while you were riding in the smaller chainring -- like the chain climbed up the chainring and fell off? If that happened, I'd say uneven wear on parts.

If it happened when you shifted from the large to small chainring, I'd check the limit screw and see if the derailleur cage is on an angle to the centerline of the bike. Sometimes it's necessary to position it like that to aid shifting, but doing so can also defeat the purpose of the limit screw, especially when shifting from a large chainring (50t) to the small chainring (34t) at speed.

When this happens to me it's usually after I replace a front derailleur cable. Everything is fine in the workstand, but there's usually some on-the-road fine-tuning on the first ride.

[Judd]

The other thing that I can think of is how you're shifting. If you're holding the shifter down for a long time when shifting, this can cause an overshift and a chain drop.

[hozn]

Just switch to 1x and you'll never have this happen again.

I have run K-Edge chain catchers (and various other chain catchers). What is really terrible is when the chain drops off despite the chain catcher and then you have to loosen the FD bolt just to get the damn chain back on. Yeah, I was serious about 1x; front derailleurs really suck (pun unintended, but I'll take it).

[mstone]

That looks more like chain drop than chain suck--lower chain looks like it got hooked while loose, rather than having the top surface of the lower chain stuck to the ring. It's usually not impossible to drop a chain shifting from the big ring to the little ring while the chain is on the big cog. The best fix is to avoid that (among other things, it implies cross-chaining before the shift). To make it completely impossible for the chain to come off doing that, the front derailleur cage needs to be far enough outboard that it'll rub sometimes. If it falls off a lot, or while making less dramatic shifts, then I'd check the limit screws, see if the FD is straight, etc. Messed up RD could also affect this, but you should have issues shifting in the rear or at least some nasty noise in that case.