I have recently acquired a steel framed bike and on assembling all the bits I realise that the mech hanger is bent. I should add that the mech hanger is integral to the frame (i.e. not replaceable).
If I want to try to straighten the mech hanger, does it help to warm up the metal first or should I just gently lever it back into as close to true as I can? Obviously I want to try to avoid work hardening/cracking the mech mount where it meets the drop out.
Any tips?
Thanks
There's a really good tool for doing it. If you have a decent LBS then it would be worth a few quid to have it done for you.
You can use a big adjustable wrench to bend it, but aligning it properly by eye is very hard. Find a shop that has one of these, and alignment should be perfect.
[url= http://www.parktool.com/product/derailleur-hanger-alignment-gauge-dag-2-2 ]http://www.parktool.com/product/derailleur-hanger-alignment-gauge-dag-2-2[/url]
[img] 
[/img]
Ive never bothered heating steel drop outs and yet to crack one ,
The above tool takes the guess work out of it but if your useing 5-8 speed Id be tempted to give it a bend by eye.
I prefer to do it with a bolt screwed into the frame rather than just an empty hole to distort
After years of bending them by eye and struggling with one particular bike I bought the Wiggle OB version of that tool. It's one of those things I wish I had bought years ago and not expensive. It's also surprising how little you need to bend the hanger and having the tool will mean you get it right without putting undue stress on it.
If you have an old wheel with qr hubs, the axle will actually screw into the hanger. Great for seeing how straight the hanger is and to bend it back into shape.
i.e. take your front wheel off, remove the skewer, remove derraileur, screw in wheel/hub/axle into hanger, check against back wheel.
Front wheel is 9mm, rear is 10mm. Front might clamp into the hanger.
I can straighten by spanner and eye but it's not for everyone.
Give it a go though, be careful, what's to lose.
Whoops ,that is correct, a Google suggests that a rear wheel will fit. I have done it before but it was a while back.
Thanks for all your suggestions.
I gave the "gentle persuasion with an adjustable & judge it by eye" method a go and can now get the back wheel in & out with only slight restriction.
Once I have ridden it a bit I will ask the lbs to check/adjust it with the tool you linked to.
STW forum help when you need it - thank you all.
I've always used an adjustable spanner works perfectly everytime.
Once the mech is on you can see how straight it is pretty well
It's yet another topic that some people think requires high precision and fancy tools.
It just takes skill.
Swoons..
