Bent rear derailleur hanger

[niloc]

My son has fallen on ice and bent his rear hanger just enough to shift the chain to the next sprocket . Does anyone have any tips on how to bend it back? E.g. should I try to straighten it while it is still on the frame?

[landsurfer]

If a removable alloy hanger heat to 80 degrees c in the oven and hammer it flat on a steel surface. . Back of a vice is fine. If removable steel, hammer it flat. If integral steel drop out then use an adjustable spanner as a lever . . If you want a talk through drop me a pm. I've sorted this issue dozens of times.

[Valbrona]

1/ Do what lansurfer says.
2/ Buy a new hanger. But it is sometimes difficult to find a match.
3/ Take it to a bike shop where the people have a 'derailleur hanger alignment gauge', or buy one yourself.

[drossall]

I did a steel integral one this weekend. As above, use an adjustable spanner. Make sure the wheel is bolted in place, above the actual hanger (not pushed to the back of the drop-out, but most of the way forward). Then it will support the main drop-out, so that you straighten the hanger rather than twist the drop-out.

If the drop-out is removable (as many are these days), I'd probably replace it, but you need the correct one for your frame. A photo would help if you want more information, and the make and approximate year of the bike.

[Des49]

For years I have got away with a spanner on the rare times I have needed to. However one of my daughters has a 10 speed racing bike that is obviously more sensitive to my 7 speed bikes to any misalignment.

So a few weeks ago I treated myself to a Park Tool Mech Hanger Alignment Tool DAG2 - http://www.chainreactioncycles.com/uc/e ... -prod35945

This really makes the whole job so much easier and accurate I wish I had got this tool a long time ago. I found her hanger was bent out by a surprising amount and the tool allowed a high degree of accuracy in re-alignment. It showed up misalignment on a couple of other bikes too that I thought were ok and improved the gear change noticeably on one of them.

Not something that will see a lot of use (I hope!), but I am very happy to now have this tool in the shed even though it costs about £50 and won't be used frequently.

[rjb]

If its a steel hanger as part of the drop out you can use a rear wheel as an alignment tool. The rear wheel axle is the same thread size as the drop out.

[drossall]

Yes, someone pointed that out in another thread. You leave the rear wheel in place and borrow another, which you screw into the hanger thread. Then you use that as a lever to bend the hanger until the two wheels are parallel, giving a very accurate gauge of whether the hanger is straight.

Very clever.

[Des49]

If its a steel hanger as part of the drop out you can use a rear wheel as an alignment tool. The rear wheel axle is the same thread size as the drop out.

Great tip thanks. Could be very useful out on the road.

[Redvee]

I bent the hanger on my steel Kona frame and managed to KO the thread too so rode with a shortcage TY15 mech that didn't index on the 8 speed cassette atall so used a cheap friction shifter till I got hold of a hanger repair nut.

[Brucey]

If its a steel hanger as part of the drop out you can use a rear wheel as an alignment tool. The rear wheel axle is the same thread size as the drop out.

Ideally you need two wheels with solid axles to do this. The wheel (esp a rim-braked wheel) in the frame is best reversed so that the sprockets don't get in the way. This leaves enough room for the second (levering) wheel to be positioned and wielded. [For this job it is probably best if both track nuts on the gear hanger are solid ones with a built-in flange as these are stronger in bending].

A typical shimano rear hub will have an M10 x 1mm thread on the axle which is a good fit in the gear hanger. However many other rear hubs (eg many inexpensive ones with solid axles) still have a 3/8" x 26 tpi thread. IMHO it is OK to use one of these (as the 'lever') but only if you run the axle through the hanger and then tighten the track nut on the back (i.e. as if there were no thread in the hanger at all). The thread looks like it will work OK without the nut but it is actually a bad fit and will likely strip as soon as you start bending any.

If you don't have a second rear wheel at all (or only one with a solid axle) then this scheme can still work OK with a QR wheel (even a front wheel) in an aluminium gear hanger. Provided the wheel in the frame is reversed you will usually have enough room to install the QR on the levering wheel, and the force required is not so great with an aluminium gear hanger. With a steel frame/hanger, I'd use a pair of solid axles for this job; the forces required are much higher.

cheers

[darkvalley]

As mentioned by someone above, a hanger alignment tool is a good investment for modern bikes. 10 speed derailleurs don't have a lot of tolerance for misalignment and 11 speed will be worse. I got an x-tools one from chain reaction last year for €40 (about £30). Simple to use, very accurate and handy to have.