Bent mech or rear derailleur?
03-21-24, 01:26 AM
#1
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Bent mech or rear derailleur?
I had a little accident on my bike last night.
The rear Derailleur and small cogs seem to be pushed into the spokes.
I Have a hybrid 21 speed bike.
I'm not sure what is bent. Is it the Mac or is it depart where the small cog attaches to. At the top it seems bent away from the structure it is attached to.
Does everything have to be straight and can anyone identify where the real problem is here?
Please let me know if you require any more photos.
Thanks
The rear Derailleur and small cogs seem to be pushed into the spokes.
I Have a hybrid 21 speed bike.
I'm not sure what is bent. Is it the Mac or is it depart where the small cog attaches to. At the top it seems bent away from the structure it is attached to.
Does everything have to be straight and can anyone identify where the real problem is here?
Please let me know if you require any more photos.
Thanks
03-21-24, 02:15 AM
#2
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It appears that the pulley assembly got caught in the spokes, and is now bent. These are rarely sold as spare parts, so it's likely that the derailleur (mech for Brits) needs replacing.
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03-21-24, 02:26 AM
#3
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I'm assuming that upper pulley is supposed to sit flush with the metal bracket holding it? Is that right?
03-21-24, 02:41 AM
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hanger also looks bent to me. Angle isn’t parallel with the small cog.
Last edited by choddo; 03-21-24 at 02:45 AM.
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03-21-24, 04:43 AM
#5
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yes. You could try. If it’s weakened it might fail in future and cause a pretty impressive accident. It’s also very likely you won’t get decent shifting back. Mechs like that are cheap. I would replace it.
hanger also looks bent to me. Angle isn’t parallel with the small cog.
hanger also looks bent to me. Angle isn’t parallel with the small cog.
The cog should be parallel to the bracket it's. mounted on.
That's the hanger you said? I'll look that up
03-21-24, 06:43 AM
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Where rear derailleur mechanism attaches to the bike is called the derailleur hanger.
I can think of three types of hanger.
1 permanent/integral to the frame. These are not replaceable.
2 A separate part attached to the frame. Usually soft aluminum and designed as a sacrificial weak link. These are replaceable.
3 The hanger is built into the rear derailleur. Obviously replaceable by replacing the entire assembly.
There is a tool to align a hanger so that the rear derailleur is held parallel to the wheel and rear gears.
After a problem like yours the alignment must be checked, else gear changes can be erratic.
Barry
BTW your rear derailleur (RD-TY500 if I read it correctly in the photo) Appears to be about $15, but does come in different fitments (hanger styles) and cage lengths.
Do be sure to get the correct one for your bike.
I can think of three types of hanger.
1 permanent/integral to the frame. These are not replaceable.
2 A separate part attached to the frame. Usually soft aluminum and designed as a sacrificial weak link. These are replaceable.
3 The hanger is built into the rear derailleur. Obviously replaceable by replacing the entire assembly.
There is a tool to align a hanger so that the rear derailleur is held parallel to the wheel and rear gears.
After a problem like yours the alignment must be checked, else gear changes can be erratic.
Barry
BTW your rear derailleur (RD-TY500 if I read it correctly in the photo) Appears to be about $15, but does come in different fitments (hanger styles) and cage lengths.
Do be sure to get the correct one for your bike.
Last edited by Barry2; 03-21-24 at 10:44 AM. Reason: Typo’ed 500
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03-21-24, 08:44 AM
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Hanger looks straight to me (at least in relation to the rest of the dropout). I'd try bending the cage back. Looks like the cage is made of steel--I wouldn't worry about it failing any time soon, even after straightening it.
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03-21-24, 08:54 AM
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The “TY500” on the derailer gives the whole ball game away. That is a Tourney rear derailer and they are made of the softest metal on the planet. The derailer arm is bent and, while you could try to straighten it, it will only bend again. Paper clips are less prone to bending than the Tourney. Just replace it with a Alivio or Acera. Slight more expensive but vastly superior.
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03-21-24, 10:04 AM
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It's a $10 unit - replace it. Better yet, upgrade to a $15-20 Altus or Acera derailleur
https://cambriabike.com/products/shi...BoCrH4QAvD_BwE
https://cambriabike.com/products/shi...BoCrH4QAvD_BwE
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03-21-24, 07:02 PM
#11
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Since the OP's profile gives a location of "down under" - e.g., Australia - this link might be of a bit more use to him/her (shipping US/AUS and vice versa as I recall is pretty steep):
https://www.amazon.com.au/s?k=Bike+D...%3A24522872051
OP: if your setup is 3x7, this one might get you back on the road without breaking the bank, assuming it's the correct mounting type for your bike:
https://www.amazon.com.au/SHIMANO-Cy...dp/B005CMUQU0/
If this one isn't compatible or to your liking, the first link lists many others.
After procuring any replacement, aligning (or having someone align) the derailleur hanger would be a great idea.
Best of luck. And if no one has said it yet: welcome to Bike Forums.
https://www.amazon.com.au/s?k=Bike+D...%3A24522872051
OP: if your setup is 3x7, this one might get you back on the road without breaking the bank, assuming it's the correct mounting type for your bike:
https://www.amazon.com.au/SHIMANO-Cy...dp/B005CMUQU0/
If this one isn't compatible or to your liking, the first link lists many others.
After procuring any replacement, aligning (or having someone align) the derailleur hanger would be a great idea.
Best of luck. And if no one has said it yet: welcome to Bike Forums.
Last edited by Hondo6; 03-21-24 at 07:07 PM.
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03-21-24, 07:06 PM
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Given the circumstances, checking/straightening the hanger would be SOP before mounting the replacement RD.
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
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03-21-24, 07:11 PM
#13
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There are 3 pics of the "tree" How about from a bit further back & side so we can see some "forest"?
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03-21-24, 08:21 PM
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It's not an expensive derailleur...buy a new derailleur and make sure the hanger is properly aligned...it is likely bent as well
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03-22-24, 08:21 AM
#15
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Thanks for all the help!
I appreciate all the responses it's been very useful.
I'm also amazed that you've been able to identify my derailleur just from a picture.
I will look into all those things and probably replace the Derailleur at some point.
Just so you all know I am in Australia. Some of the links are US but I am sure I could find some of those things in Australia
I'm also amazed that you've been able to identify my derailleur just from a picture.
I will look into all those things and probably replace the Derailleur at some point.
Just so you all know I am in Australia. Some of the links are US but I am sure I could find some of those things in Australia
03-22-24, 08:26 AM
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03-22-24, 08:58 AM
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It looks like it is steel, so bending it back is possible but you want to look at the metal after it's bent. If the surface of the metal is crazed (or worse, cracked) then you need a new derailleur. But if the metal shows no surface changes, you are PROBABLY OK to bend it. If the cage is aluminum there is no way it would be safe to bend it back. The upper and lower pulleys need to be in a vertical plane, parallel with the plane of the cogs on the cassette/freewheel.
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03-22-24, 09:45 AM
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Besides all the other damage already mentioned. In the first picture, the two lower teeth on the 11 tooth sprocket look bent outward!
Probably just the camera angle and the normal individual shaping done on some sprocket teeth. But I can't seem to make my 11 cog look like that. Though I don't have the same cassette and series components.
Probably just the camera angle and the normal individual shaping done on some sprocket teeth. But I can't seem to make my 11 cog look like that. Though I don't have the same cassette and series components.
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03-22-24, 09:45 AM
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Even if it was aluminum, you’d probably have no problem bending it back. Aluminum isn’t pot metal. How many times can you bend the pop-top tab of an aluminum soda can back and forth before it breaks?
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03-22-24, 10:38 AM
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