Barry2 

Bike fell over on the drive side (my fault) and since then I've been having troubles with gear changes that won't adjust out..
I've measured and the hanger is out of alignment.

The RD hanger is held onto the dropout by two small screws and NOT trapped by the Wheel QR.
All of the stress of straightening the hanger would be taken by the dropout/frame.

With this kind of setup is it really OK to straighten it on the bike or will I break the dropout.

Thanks

Barry

trailangel

Standard procedure is straighten the hanger with the rear wheel on the bike.... hanger on bike.
It's hard to align hanger when off the bike.
Without seeing your situation I cannot say for certain.

leob1

What is the hanger made of? If it's aluminium, which most if not all are, it will most likely break when you try to bend it back flat. They are replaceable, it's best to just get a new one and replace it.
I've gotten lucky once or twice flattening a hanger, but most of the time they crack.

davidad

If you don't have the tool you can realign the hanger with a spare wheel if you have one. Remove the der. and thread the spare back wheel into the hanger and use it to bend and check the alignment of the two side by side wheels. It's also a good idea to buy a spare hanger to have on hand.
There are only about 450 different hangers available!

79pmooney

I have an aluminum hanger on a ti frame. Bent like yours. Took it off, put it in a vise and gently bent it straight (to a straight edge laid in it) with a large crescent wrench. Put it back on, Much better shifting. I haven't yet built the tool to accurately measure the hanger but I can see that the derailleur lines up far better. A new hanger will go on when I have a chance to go pick it up. (Gotta combine/reduce errands - this COVID thing.) The new one will be steel and I won't have to worry about multiple bends breaking it (within reason).

Ben

Barry2 

First thing I did, even before removing the RD was to order another hanger.
The one that is on the bike is out by 3/8". As measured at the rim of the wheel. Upper limit I believe is ~1/8"
So alignment would require 1/2 that... a 3/16" bend.

New and old hangers are metallic and do not stick to a magnet.

If you follow this link
Mine is the 156 type and so only partially trapped by the rear wheel
Unlike the 101 type that is completely trapped by the rear wheel.

I could just install the new one, but I was under the impression that new hangers still need aligning?

Barry

trailangel

Ya, a new hanger would still need to be checked for alignment with the wheel and hanger on the bike.
If your hanger is really bent a lot, take it off and straighten in a vise or with crescent wrench or something.
Put it back on the bike with wheel on and touch it up a little.

Barry2 

Played chicken.... went to my usual LBS.

Walked in the door and was told: "It might break when we straighten it"
I replied: "I've got a new one in my pocket"
Reply came back: "you have a spare, then there is no way this one will break!"

Total time to straighten, 10mins or less, the deed is done.

Thanks guys.

Barry

fietsbob

Your rear wheel is the plane of reference that you use to get the derailleur hanger aligned with the shop tool..

More 'speeds' in the cassette, the more having the job done accurately, matters ..

aggiegrads

Ben, PM me if you need to borrow a hangar alignment gauge.

aggiegrads

I had the same thing happen to my cross race bike (Kona Jake the Snake), I bent the hangar, pulled the RD into the spokes, and had to rebuild the wheel. Even the chain bent.

Replaced the RD, chain, a few spokes, and ordered a new Aluminum hangar. I was able to straighten the old hangar and have crashed it twice since and straightened the hangar.

If I didn't have a new one sitting in my parts bin, I'm sure that it would have cracked on my first try.

zacster

I bought the tool years ago and check mine every once in a while, maybe yearly. Of course since I have the tool I've never needed to realign any bike after the first use.

aggiegrads

You must not have kids.

Barry2 

Because kids bend alot-o-hangers ????



Barry

aggiegrads

Kids and adults that act like kids.

zacster

I have 3 adult kids, 2 at home at the moment. But even when they were little they never went near my bikes. They each have their own road bikes now, and of course I'm still the master mechanic for them.

JohnDThompson 

+1 this. A trued, properly dished wheel serves as a reference plane for the hanger alignment tool.

Retro Grouch 

1. Can you ride your bike the way that it is now? If your answer is "no" you have nothing to lose by trying to straighten your derailleur hanger. FWIW, I've bent back some pretty seriously bent aluminum hangers and have never had one break on me - yet.

2. How many rear cogs do you have? Up to 8, I can eyeball the alignment adequately. Don't try to bend the hanger without having a bolt in the derailleur mounting hole because you might ovalize the hole. I leave the derailleur in place and bend it with my hands if I can. Otherwise I clamp a big Crescent wrench over the derailleur. I don't even try that with more than 8 cogs because the cogs are so closely spaced that you have to be pretty accurate. I have the Park Tool alignment tool which works well.

3. If you don't have an alignment gauge, you are still in luck. The work around is to use your front wheel. Remove the quick release and screw your front wheel axle into the derailleur hanging hole. Make your front wheel totally parallel to your back wheel and you're good-t0-g0.

davidad

The front won't work because of the different size axle (9mm). The der. bolt is 10mm.

joeruge

It is my understanding that these aluminum RD hangers are designed to be realigned on the bike with the rear wheel in place and the QR clamped tight.

Minor 'injuries' can be corrected several times before you have to worry about replacing the hanger. Obviously, one big accident can spell the end of the hanger, but it's worth a try. If it's going to break, it will likely happen when you bend it back, and not so likely to happen while riding the bike. Putting a severely bent hanger in a vice to get it close, is not a bad idea, bit you will still have to do final adjustment when it's on the frame.

For various reasons, even putting a new hanger on the frame is no guarantee it will be aligned when tightened up. A new one will also have to be checked and possibly adjusted.

WizardOfBoz

lol.