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Broken Derailleur hanger twice

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Broken Derailleur hanger twice

Old 09-04-21, 06:42 PM
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skloon
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Broken Derailleur hanger twice

This is on a KMX Cobra trike- the previous Sram X5 was bent and the hanger cracked- I replaced both and noticed that I was getting some skipping on 3-6 on an 8 speed- then it went and snapped the mount again, at $90 per mount I don't want to be doing this weekly- any ideas why this might be happening
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Old 09-04-21, 07:47 PM
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$90.00 for a hanger?!? That's crazy. It shouldn't 'snap' all by itself, there is zero tension on it when you're pedaling. You're gonna need to provide some photos if we're going to have any idea what's happening.
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Old 09-04-21, 08:19 PM
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Are you shifting under load (like up a hill or putting a lot of pressure on the pedals)? Are you hitting rocks or other obstacles? All of that can cause issues. Also not adjusting things properly from the derailleur to aligning the hanger will cause issues. Generally poor shifting or crashes tend to be the biggest issue in broken hangers or derailleurs but improperly adjusted derailleurs and hangers will also cause issues.

I can't imagine the hanger is $90 as the trike is hi-ten steel and cheaper components. Utah Trikes which is the website that KMX sent me to, when I clicked home, has a derailleur hanger for the KMX trikes for $19.95. Generally most decent hangers from Wheels MFG are going to be around $30-40 in a shop which is not terrible.

You might be a good candidate for a proper hanger adjustment tool and watching plenty of videos to learn how to use it properly. Park Tool makes the DAG.3, Abbey makes the HAG, Wolf Tooth makes the portable Pack Hanger Alignment Tool and there are others out there like Shimano or EVT (both quite similar as EVT helped design the Shimano tool) but get something of good quality as cheap tools are for rich folks who can buy new tools all the time or can just attempt to use the tool fail and bring it to a shop. A good tool is always worth it if it keeps you riding and makes sure everything is properly adjusted not stripped or damaged...
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Old 09-04-21, 08:43 PM
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Perfectly flat ground low speed wife was riding and this bracket has 10km on in and it broke in exactly the same place a s the previous They are $30 plus $30 shipping to Canada and then the exchange- I did find them locally for$32 though but something is wrong here


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Old 09-04-21, 08:51 PM
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You shouldn't be breaking hanger s that often. Is the derailleur properly adjusted? Is the hanger properly aligned (even new hangers need to have alignment checked)?
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Old 09-04-21, 09:27 PM
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In addition to alignment I would make sure that the chain isn't locking up the derailleur or a bad derailleur jockey wheel. It takes quite a bit of force to tear the hanger apart like that.
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Old 09-04-21, 10:30 PM
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The jockey wheels are fine- I will check the chain- as it is on a tadpole trike the derailleur alignment tools won't fit it
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Old 09-04-21, 10:36 PM
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Have you paid any mind to the derailleurs capacity?
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Old 09-05-21, 01:23 AM
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How low does it sit to the ground? Any chance she is hitting it on a curb or parking stanchion ? Is there a "B" screw adjustment on the derailleur?
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Old 09-05-21, 07:03 AM
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Is the chain long enough?
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Old 09-05-21, 08:17 AM
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Originally Posted by skloon View Post
This is on a KMX Cobra trike- the previous Sram X5 was bent and the hanger cracked- I replaced both and noticed that I was getting some skipping on 3-6 on an 8 speed- then it went and snapped the mount again, at $90 per mount I don't want to be doing this weekly- any ideas why this might be happening
Iím thinking too short chain. The only reason the RD hasnít failed is that the hanger has a lousy design (screw hole in the middle of the extension) and failed first (sacrificial RD hanger). Barring direct impact, the only significant force an RD will encounter is the forward pull of a too-short chain, which can pull the RD right off the frame
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Old 09-05-21, 11:14 AM
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Originally Posted by Litespud View Post
Iím thinking too short chain. The only reason the RD hasnít failed is that the hanger has a lousy design (screw hole in the middle of the extension) and failed first (sacrificial RD hanger). Barring direct impact, the only significant force an RD will encounter is the forward pull of a too-short chain, which can pull the RD right off the frame
I did have to shorten the chain as I shortened the boom but only 4 links and that was just enough to stop the chain from slapping the boom in the front granny ring

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Old 09-05-21, 12:37 PM
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That is a poor design for a hanger... With the bolt through the highest stress point. That being said. What is up with your chain? Two different chains? What is the width on them and is it catching in the cage or jockey and ripping the RD during a shift?
I would place it in stand and run through the gears and shift it around (after a new cage is installed), rough, nice, fast, slow, (Try and shift the worst way you have on the road) to see if it is catching something and pulling the derailleur away. Measure the chain and the cage to make sure it is within spec and replace the chain if it isn't.
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Old 09-05-21, 02:04 PM
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I will try that- it is the original chain but is made up of two or three to get the length needed
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