Rear dérailleur hanger - how bent is too bent?

[LittleSkink]

Been offered a nice 1990's CrMo frame with a bent rear hanger - it isn't really bad but worse than any I have fixed before

Holding the hanger with an adjustable spanner it looks like about 25 to 30 deg inwards (ie horizontal toward wheel) and, maybe more concerning, 25 to 30 degree twist (ie towards front of the bike). Looks to be a welded on hanger rather than brazed

Any thoughts?

 

[jimo746]

Any amount of bent is too bent. It's true that you can adjust the mech and live with a slight bend, but 30° is not a small bend.
Being steel though you should be able to bend it back into shape, otherwise it's probably a job for a framebuilder or machine shop.
Or just run it singlespeed?

 

[greencat]

Or if the drop out isn't affected, you can saw it off and fit one which goes around the axle.

 

[mechanical_vandal]

Re:

^ Bit drastic and there'd be a load of alternatives I'd be trying first if it were a frame of mine.

To be honest though, if it were a frame I was looking at buying, I'd be walking away unless it's super rare or at a super good price etc.

 

[mattr]

Heat and slow movement. Should be able to get that back.

do the initial adjustment with an axle threaded in to the hole, then the next stage with an axle (or hub) between the drop outs.

Final stage with the proper tool.

 

[hamster]

As mattr says. Chas May sorted out a mech hanger that ended up pointing upwards afer a brach stuffed my rear mech into the wheel. His only advice was that I would probably have to get the frame heat-treated again were I to do it again. Clearly he had taken a torch to bend it back without breaking.

 

[mattr]

BTW when I say slow movement, I mean slow and steady. Try and minimise stopping and starting.
Try and work it into two or three big movements. Then a final tweak with the alignment tool

 

[datmony]

Back in the day on my MB1, I got a stick stuck in my derailleur and mangled my hanger. I was absolutely heart broken. Poor college student..... my most prized possession mangled..... the hanger at a 90 degree angle to where it should be..... the threads an oval.

I took it to my local shop where Saki, the surly old asian owner looked at it and was like bahhhh, we'll get this for you.

He proceeded to heat it and bend it, slow and steady as Mattr is noting. He also was periodically using water to flash cool the steel because he wanted to tighten up the threads and try to get them as close to a circle as possible again. I literally saw a wizard at work that day. That was 20 years and 20K+ miles ago on that frame and it still works as well as the day he repaired it. Very worst case an experienced frame builder could have cut that hanger off and brazed a new one on as well and it would still be going strong.

My take would be when it comes to good steel, it is never too bent.....

 

[legrandefromage]

Pictures tell a million billion words. I've (yes, me again) bent back a few without much fuss.

 

[integerspin]

I have had to straighten a few;-)