back derail hanger broke

stevechow said:

hi, i have BH CONNECT which i bought last year. it's quite a good bike after i am used to it. then last week the hanger broke into 2 pieces while i was cycling and i fell off. i did not hit anything. so i wondered how did it break. the back derail curls up and hit the leg of the frame causes teeth marks on it. i was told by mechanic, the back derail curls up and knock down the hanger as well. i don't think so i think it is the hanger broke and causes the back derail to fail and therefore it curls up. so which is correct. anyway i suspect the hanger is fragile not built to quality. what can i do in future to prevent it from happen again.

Was the portion of the hanger which was still attached to the frame securely attached or loose?

Did you examine the edge of the break AND is there a discernable bubble in the extrusion/casting/whatever?

If the portion of the hanger that was still attached to the frame was loose, then the break is due to fatigue cause by the stresses of shifting/etc.

If there is a bubble, then it is a manufacturing flaw.

If you are concerned about the next hanger, then you can fabricate your own from some sheet steel (10x1 threading for the derailleur mounting hole) OR cannibalize a hanger from a steel framed bike whose dropout has an integrated hanger (and, file-it-to-fit in the BH frame's dropout).

stevechow said:

hi, i have BH CONNECT which i bought last year. it's quite a good bike after i am used to it. then last week the hanger broke into 2 pieces while i was cycling and i fell off. i did not hit anything. so i wondered how did it break. the back derail curls up and hit the leg of the frame causes teeth marks on it. i was told by mechanic, the back derail curls up and knock down the hanger as well. i don't think so i think it is the hanger broke and causes the back derail to fail and therefore it curls up. so which is correct. anyway i suspect the hanger is fragile not built to quality. what can i do in future to prevent it from happen again.

Cheers,
Cao

I suspect the chain got jammed into the rear derailleur somehow, busted chain link, into the spokes, something, stopped the chain which THEN curled the rear derailleur aft, breaking the der hanger. Not uncommon. I don't think the der hanger broke first.

Peter@vecchios said:

I suspect the chain got jammed into the rear derailleur somehow, busted chain link, into the spokes, something, stopped the chain which THEN curled the rear derailleur aft, breaking the der hanger. Not uncommon. I don't think the der hanger broke first.

how do i check if the chain link is busted. it looks ok the chain, i didn't see any broken links. and i don't know what to do with the scratches. what can i use to fix the scratches.

Cheers,
Cao

not sure how well this will work on a bicycle but thought it'd be worth a shot. your story sucks btw, sorry to hear that it happened.
https://www.asseenontvadvisor.com/buyfixit/index.asp?did=978&phone=&refcode=mFI3

First, OP, don't click on the link provided in the previous post: it's of questionable intent.

Who put your bike together? It's also possible that your chain is too long. With a too long chain and a bump or two of the right kind, you can experience what you did. As Peter said, it's not your derailleur hanger, unless it somehow got bent or was out of alignment. Did you check to see if there was any damage or marks on the spokes? Improper derailleur limits can put the pulleys into the spokes, pulling the derailleur off, breaking the hanger in the process.

alienator said:

First, OP, don't click on the link provided in the previous post: it's of questionable intent..

huh? not sure what you mean but i will say that i've personaly never used the stuff but it is what came to mind.

Link is safe, but looks irrelevant. Looks like something I saw advertised on TV a while ago for scratch repairs. Won't do anything for broken parts.

cyberlegend1994 said:

Link is safe, but looks irrelevant. Looks like something I saw advertised on TV a while ago for scratch repairs. Won't do anything for broken parts.

OP/(stevechow): "... and i don't know what to do with the scratches. what can i use to fix the scratches."

alfeng said:

OP/(stevechow): "... and i don't know what to do with the scratches. what can i use to fix the scratches."

I was referring to the busted derailleur, not the scratched frame.

cyberlegend1994 said:

I was referring to the busted derailleur, not the scratched frame.

Yes, you were ...

But, you stated that roadhouse's reply was "irrelevant" whereas the OP additionally wanted to know what he could possibly "use to fix the scratches" ... although I'm not sure the particular product will suffice, I would hardly say the particular reply was irrelevant.

alfeng said:

Yes, you were ...

...I would hardly say the particular reply was irrelevant.

I stand corrected... 🙄

i appreciate the good looking out, alfeng. i was wondering what in the heck was going on and for why and then realized alienator was involved again and it all made sense. cyber, go to your room. :eek: