Snapped derailleur hanger

[joelectric]

Hi,

Looking for some help in sourcing a replacement derailleur hanger as my old one has snapped off. Unfortunately, the top half of the hanger that fits into the frame is missing along with the fixings.
I am sure the derailleur model is a Shimano Rd-Ty21. (7speed)
The bike is a generic Chinese electric MTB I think its a rebadged CNE bikes mr275a. I contacted CNE a few days ago but have heard nothing back.

I have attached on some pictures of the frame, derailleur and broken hanger that might help.

 

[wheeliepete]

The other half of the hanger is behind the axle nut in your 3rd photo. Remove the nut and the allen key bolt and you will be able to match yours to the many for sale on ebay.

 

[Andy-Mat]

Hi,

Looking for some help in sourcing a replacement derailleur hanger as my old one has snapped off. Unfortunately, the top half of the hanger that fits into the frame is missing along with the fixings.
I am sure the derailleur model is a Shimano Rd-Ty21. (7speed)
The bike is a generic Chinese electric MTB I think its a rebadged CNE bikes mr275a. I contacted CNE a few days ago but have heard nothing back.

I have attached on some pictures of the frame, derailleur and broken hanger that might help.

You have docuented the problem well I feel, and really got me interested in "why"?
I have never seen one break like this! I have even bent one back into proper shape many years ago, with no further problems. The bike fell over I believe, but its maybe 30 years ago!
Does anyone on Pedelec know of similar happenings?
Is there anything one can do to avoid such happenings?
Or is it a fault of the design maybe?
Bike falling over maybe?
regards to all and thanks in advance for any input!
Andy

 

[joelectric]

The other half of the hanger is behind the axle nut in your 3rd photo. Remove the nut and the allen key bolt and you will be able to match yours to the many for sale on ebay.

Ooft, so it is. I don't know how i missed that, i just assumed it had fell off from the gap section on the frame next to it.
I will remove it later and piece it back together and post another picture, thanks.

 

[joelectric]

You have docuented the problem well I feel, and really got me interested in "why"?
I have never seen one break like this! I have even bent one back into proper shape many years ago, with no further problems. The bike fell over I believe, but its maybe 30 years ago!
Does anyone on Pedelec know of similar happenings?
Is there anything one can do to avoid such happenings?
Or is it a fault of the design maybe?
Bike falling over maybe?
regards to all and thanks in advance for any input!
Andy

I had the wheel and derailleur off because i was changing the 14-28t freewheel over to a dnp 11-34t to alloW more pedaling assistance at higher speeds and for off road hills.

I have probably not got my chain line correct or something

 

[joelectric]

I had the wheel and derailleur off because i was changing the 14-28t freewheel over to a dnp 11-34t to alloW more pedaling assistance at higher speeds and for off road hills.

I have probably not got my chain line correct or something

i only got about 2 miles of testing the new freewheel before the hanger snapped

 

[JPGiant]

More likely to be wrong setting of Hi and/or Lo screws settings, or B screw setting to accommodate larger 34t gear, than chain line.
Unless the number of gears have also changed???

 

[BazP]

You have docuented the problem well I feel, and really got me interested in "why"?
I have never seen one break like this! I have even bent one back into proper shape many years ago, with no further problems. The bike fell over I believe, but its maybe 30 years ago!
Does anyone on Pedelec know of similar happenings?
Is there anything one can do to avoid such happenings?
Or is it a fault of the design maybe?
Bike falling over maybe?
regards to all and thanks in advance for any input!
Andy

I have no experience with this particular hanger but with hangers in general I've had two or three break over the years, two from getting a knock on the derailleur and one from me trying to straighten a bent hanger. Hangers are designed to snap rather than the derailleur getting damaged. I always carry a spare hanger in my kit.
I have a special tool for straightening hangers but my local bike shop recons that his success rate of them not snapping is about 50%

 

[Andy-Mat]

I have no experience with this particular hanger but with hangers in general I've had two or three break over the years, two from getting a knock on the derailleur and one from me trying to straighten a bent hanger. Hangers are designed to snap rather than the derailleur getting damaged. I always carry a spare hanger in my kit.
I have a special tool for straightening hangers but my local bike shop recons that his success rate of them not snapping is about 50%

It does need to be carefully warmed up with a torch flame first, to reduce the possibility of breaking, but not made anywhere near red hot.
Basically just far too hot to touch with your fingers!
You know when its right when when it "moves" when pulling & pushing on it with a wrench, or tapping with a hammer, as it will fairly "suddenly" start moving under such pressure.
When its the right shape again, drop it immediately into normal (cheapo) motor oil, that cools it quickly and if its a metal that will rust or is chromed (maybe not anymore today, I don't know either way what they are made of!), also makes it slightly more rust resistant.
Its a bit like the "Browning" on a gun barrel.
I always do it to the tools that I have modified over the years for fishing, for example. Some of them I "browned" 50 years ago, and they are still rust free....
The oil gets into the metal somehow I believe!
In the RN then, it was quite normal to protect tools that you owned. I still have them as well!
Salty air was/is a killer for unprotected quality steel tools.
Andy

 

[soundwave]

well it has a P on it and found this one. https://www.ebay.co.uk/itm/Various-Mech-hanger-Derailleur-hanger/133084149209?hash=item1efc6ef5d9:g:4wkAAOSw8PpdAm1v

 

[The Bear]

Tis the season for hangers snapping, mine snapped a few days ago, thankfully sondwave pointed me in the right direction of obtaining a replacement online..

 

[joelectric]

I got the other part of the deraliuer and have put the two parts together and have attached on the picture.

 

[joelectric]

Pic was missing, here it is

 

[joelectric]

Pic was missing, here it is View attachment 33690

The other side

 

[soundwave]

this is the closest i could match it to but check with the seller first to double check.

Rear gear mech derailleur hanger drop out Kona Giant GT CUBE Scott dérailleur | eBay

Find many great new & used options and get the best deals for Rear gear mech derailleur hanger drop out Kona Giant GT CUBE Scott dérailleur at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

 

[joelectric]

Thanks for the help Soundwave,
I ordered up that hanger you recommended and it fits perfectly. Just rebuilt bike there and took for a spin all gears are selecting now without any adjustment.
I think the reason the hanger snapped in the first place is I over-torqued the wheel up and this weakened the hanger.
I have since put on a larger washer to help spread the force of the wheel nut over a larger area, and hopefully not on the hanger too much.

The bike is completely transformed with an 11t gear now, would recommend this conversion.