Bent derailleur cage?

Discuss light weight issues concerning road bikes & parts.
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cyclochard
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Joined: Wed Jul 06, 2016 11:34 am

by cyclochard

A few weeks ago I had a crash with my Canyon Aeroad, unfortunately landed on the drive side so the majority of the impact was taken by the rear derailleur and the right brifter both got as bit scuffed but nothing major the only part i replaced was the derailleur hanger which cracked. I did get the new derailleur hanger aligned at the local repair shop so I am 100% sure that the hanger is perfectly straight.

http://imgur.com/a/Oqxst

Upon further inspection the lower jockey wheel seem to be bent outwards, what makes this a mystery to me is that there are obvious scuff marks on the parallelogram of the RD while the cage has no signs of impact, but then again if the whole derailleur is somehow bent and not just the cage then both the TOP and the bottom jockey wheels would have been out of alignment and the top jockey wheel isn't misaligned which I've visually checked (not sure if it's visible in the photos).

My question is: would it be smart to remove the derailleur and take the cage off to try and bend it back? I'm asking this because there are no signs of shifting problems, what I am worried about though is that somehow the chain will slip off the lower jockey and get stuck which can can cause all sorts of problems.

Cheers!

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wheelsONfire
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by wheelsONfire

If the shifting is working good, with no signs of missing shifts or hick ups i would leave it as it is.
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kgt
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by kgt

+1

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nycebo
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Location: New York, NY

by nycebo

Resurrecting this slightly older thread because I noticed the same thing with my new Shimano Ultegra Di2 6800 series rear derailleur. Unlike the OP, it has never been down. But it looks a little tilted, bent or twisted outwards from the wheel. Is this by design, read normal for the rear mech?

Here's a photo:
Image

NiFTY
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by NiFTY

Is the derailleur hanger straight? A lot of these aren't straight out of the box.
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nycebo
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Location: New York, NY

by nycebo

@NiFTY, I can confirm that the derailleur hanger is straight. Using the Park Tool, I straightened the new hanger before installing the new RD. It really is the craziest thing. Considering that the top chain guide wheel on the RD is directly under the cassette gear, the bottom chain guide wheel, and thus cage, looks looks twisted. I wondered if it was because Shimano want it tilted well away from the spokes. I should admit that shifting is reasonably fine.

NiFTY
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by NiFTY

Thats weird. I would leave it rather than try and bend the cage straight if its shifting fine.
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Kaboom
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Joined: Wed Mar 22, 2017 3:53 pm

by Kaboom

That cage definately looks bent to me...
If you look at the outer plate, it looks bowed out, which would make the lower pulley wheel stick outwards just like it does.
You don't need to have gone down to bend the cage. If the chain has ever gotten caught or wrapped around the casette or you have backpedaled before completing a shift it's possible that you have pulled the cage all the way forwards and bent it.

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