Berone

... but I think this derailleur has a problem.

Litespud

Looks fine to me, but that scratch on the seat stay would really piss me off....

nfmisso

it is broken.

Andrew R Stewart 

We see often enough to make some assumptions, usually they are correct.

Some how the wheel/spokes and the der cage engaged each other. Both the cage and the der body look to be twisted. The most common reason is a bent inward der/hanger allowing what was a correct low gear limit setting to now overlap with the spokes. Of course if the low limit setting wasn't correct (and people/shops that only use the shift control to cycle the der through it's range, during the limit adjustments, can make this mistake) and the cable got an extra tug or the der got an extra push then the der will enter the spokes. But a previous impact on the der's outer face, which bends the der inward, is a VERY common cause. The der/spoke engagement often happens some time later so the cause and effect cycle can be days, weeks or longer. Hence most riders won't connect the two.

Sometimes a power shift (not shifting during reduced pedal pressure) can cause the chain to jam or cause a chain link(s) to become damaged/twisted. But generally this won't tear off the cage and cause such twisting in the cage/der body. Sometimes a stick can be kicked up and enter the chain loop and the spokes and result in much the same as shown. (This happened to me, off road).

So what do you think happened?

Things to look for are a spoke with a wiggle/squiggle along it's length. Scratches on the der's outer face. The cage has a flair to the inner plate, usually next to the guide pulley.

Things to look for during the repairs are a bent axle, now out of true wheel (and maybe spoke replacement too), bent der hanger, bent drop out slot, twisted chain, mangled cable, and more. Andy

I have a sad/funny story about this kind of event for the asking.

Jon T

Good thing you have the dork disk on it. At least you saved the wheel.
Jon

Andrew R Stewart 

Almost every der snagging the spokes I've seen happens beyond the spoke protector disk. The disk is to minimize chain/spoke overshifting damage, not cage/spoke issues. Andy

rumrunn6

clean bike tho

Berone

I don't have to think- I have the bruises! I'm not much of a trail rider and I was in over my head. The trail was slick and I wiped out. I didn't see how bent the rail hanger was, and I thought I could limp out of the park. I gently cycled through the gears okay, but when I put some pressure on I felt the derailleur explode under me. It's a pretty low end Scott that I bought new for not much. When I researched for a new derailleur I found a post where someone asked what would be an upgrade from a Shimano Tourney. The reply was, "literally anything on the market would be an upgrade from a Tourney!"
What's your story?

Berone

That's a custom scratch- I put it there to make the bike look trail worn!

Berone

Don't rush to judgement!

Brofessor

Yeah, pulleys are supposed to be inside the chain stay for proper chain line.

Andrew R Stewart 

I was riding home one cold February evening, from our club's off season maintenance classes that I helped out with. Rode down a badly lit street and whacked a deep pot hole and promptly skidded to a stop. Seems that the rear wheel (ad front as it happened) had indented so far that the spoke splayed out, catching the der cage and tearing the body apart apart. Like the OP's results the der ended up above the drop out impacting the rack and fender struts. I cursed my poor observational abilities and bless that both tires still held air, their tubes just beginning to herniate. I dropped air pressure, removed the half der dangling from my chain, manually setting a rideable cog/ring combo and continued my ride home with the chain slapping against the tire's side. Wouldn't you know the other class helper who had also rode there passed me by soon. I hoped he didn't recognize me Here's a poor shot of the torn apart Campy der. Andy

ddeand 

Bill Kapaun

For a 7 speed, there's really nothing wrong with a Tourney. I think the next step up is 8 speed, which may be slightly narrower and a bit more prone to chain rub.

How did it perform until........

Looks like you need a replacement hangar too.

WizardOfBoz

Some duct tape, a bit of JBWeld, and it'll buff right out.

wschruba

More damage could have happened. Those Tourneys tend to, as your picture shows, pull apart at the plastic knuckle. A more robust derailleur might twist itself into a pretzel and do more damage to the wheel, frame, or chain. I agree that the Tourney is a perfectly serviceable (if ugly looking) derailleur. It may look different, but shares quite a bit of design with the Lark, itself a cousin of the Campagnolo derailleur Andy posted.

$0.02

fietsbob

Grab your Spare Bike and Go.

rumrunn6

when this happened last spring



this is where mine broke



2 1/2 miles from my car I was able to smoosh it all back & limp in one gear





LBS fixed me up tho



& then I added quick release tabs to the fender stays

Berone

My LBS supplied an Altus. I straightened the rail hanger, installed the Altus, and replaced the chain and cable. I got everything up and running. On the stand. Riding it there's some problems that I can't identify. At this point I think I'll take it to the shop and have them take a look. I'm not an experienced enough mechanic, since I can't even find the problem. I'll see what they say, but I'd like to be able to ride the bike again!

FlMTNdude

Troul 

were you tubeless too? I hear it may cause more harm than good for a bicycle, which might suggest why you have that scratch on the chain stay?





that broken der is no good either.

rumrunn6

was going to do my own as well. was either going to buy it on-line or from my LBS. decided I'd see the man down the street cuz there were so many choices on-line. he strongly encouraged me to let him do the work & I agreed. it was fun & educational to watch an experienced expert work. he had me road test it before I left. it's been flawless ever since

Berone

I took it to my LBS. He said I had done a good job straightening the hanger, then tweaked the tuning a little and said it looked good. Then he discovered that I made the chain too short! I thought I had followed the Park Tools video pretty accurately, but turns out not. He added a couple of links back in and it runs like a dream.