Bent derailleur hanger, steel frame

[palinurus]

I was asked to have a look at a bike the other day, see if I could fix it. All I knew was the derailleur was touching the wheel, figured it was going ping-ping on the spokes in bottom gear- a quick tweak. It wasn't; it was stuck through the spokes and bent right around. Right mess.

Old Dawes bike (Dawes Countryman- a sort of proto-MTB, odd thing), Suntour rear mech, five speed freewheel. Oddly the wheel doesn't look damaged but the mech hanger is bent inwards and the mech itself is donald ducked.

Two questions: I was thinking the mech hanger could be bent back with a big adjustable spanner- how critical is the alignment? Is this an LBS job or suitable for the general home bodger?

What sort of new rear mech could replace the old Suntour job? I expect one of the low-end Shimano mechs of the type that are attached to BSOs would do it. Period parts not required, just need to get functioning transmission.

Make that three questions: how did the wheel get off so (apparently) lightly when the mech hanger and mech were so bent? I don't get it.

 

[PpPete]

It can certainly be bent back. Can take quite a bit of tweaking to get the alignment right, although there is a tool for it that LBS will have to do it quickly & accurately.
Might have a suitable mech in the depths of the garage, save you the embarrassment of buying a low end one!

No idea on your third Q

 

[LizardEye]

I've bashed a few hangers back into shape without too much trouble. Big hammer and concrete floor is all you need. But take your time - it's easy to go too far the other way

 

[palinurus]

Ta.

Possibly something I can do then, although if the LBS will do it reasonably cheaply it could be a good option- since it'll be easier for them than me.

PorkyPete: depending on what we decide to do I might take you up on that offer.

LizardEye: I do enjoy hammering. Perhaps too much.

 

[MacB]

I did one a few weeks ago with instructions from LBS, just get a bit of threaded rod, they gave me some. Screw this into mech hanger and then I used a longer metal tube over the top. Manipulated until the rod was poking straight out at rightangle to bike. It was very easy.

 

[palinurus]

Useful, thanks.

 

[PpPete]

You will need Metric fine thread rod if you want to try that. Force regular M10 threaded bar in there and it will be fubar.

 

[Dave5N]

You will need Metric fine thread rod if you want to try that. Force regular M10 threaded bar in there and it will be fubar.

I have a tool that does just what you want it to do. You can borrow it if you want, but you'll have to come and get it.

Which probably means that your nearest bike shop - which has the same tool - is your best bet.

 

[Granville Kuosonsavath]

Make that three questions: how did the wheel get off so (apparently) lightly when the mech hanger and mech were so bent? I don't get it.

the mech's vulnerable because it's sticking out.
One of the reasons postman's bikes, boris bikes, other 'public' bikes etc have hub gears.
I bought one of the alignment tools because it is probably the single most annoying thing to go wrong on a bike becasue it screws up the gear changing completely if it is bent. Just the one tool for checking how bent it is and curing the bend, pretty easy to use.

 

[palinurus]

I guess I was assuming the bending happened after the mech ended up in the wheel. It may have been bent beforehand and that's why it ended up in the wheel.

 

[palinurus]

And it looks like someone I know has a suitable mech.