
Jim’s Tech Talk
By Jim Langley
Part 1 – The Problem And Some Tips For On-The-Road Repair
A few of you asked me to cover repairing bent derailleur hangers so that’s the topic for this week and next. It’s a good problem to understand because it doesn’t take much to knock a derailleur hanger out of alignment. Even something as seemingly harmless as putting your bike in the back of a truck or hatchback with the bike’s drive side down could bend it. Or, having your bicycle fall over and land on its drive side.
And with our modern 11-speed drivetrains and precision electric derailleurs even minor hanger bends can cause annoying shifting problems, such as hesitation, overshifts and noise.
A Recent Example
Kind of a sad story but the most recent derailleur hanger disaster I witnessed happened to a rider I befriended while we were both riding around Lake Tahoe. Closing in on the 9-mile Spooner Summit climb on the Nevada side, a person on a construction crew stepped into our path. I swerved to miss her, crashed into my new friend and we both went down in a pile.
The bikes seemed okay and the construction site had a good first aid kit to patch up our road rash. But, as soon as we hit the first ramp, my friend went to shift and the derailleur shot straight into the rear wheel breaking several spokes, mangling the derailleur and even worse, shearing off his derailleur hanger. He called home for a ride and I continued but not before apologizing for not looking at his bike more closely.
What Is It?
In case it’s new bike lingo to you, the “derailleur hanger” is the part of the bicycle frame that the rear derailleur attaches to. It’s a smallish tab that’s either part of the right rear dropout or attached to it. In the photo here the hanger is the silver part stamped with a “W.” You can see the heads of the small screws that attach it to the dropout. Oh, the “dropouts” are the part of the frame that the wheel axle fits into to attach the wheel to the frame.

Why It’s At Risk
The rear derailleur is attached to the derailleur hanger with a bolt. Because the rear derailleur sticks out from the side of the bike, it’s one of the first things to hit the ground in falls. Since the derailleur is much larger than the derailleur hanger it acts as a long lever and can easily overpower and bend the hanger.
Adding to their vulnerability, most derailleur hangers today are made of aluminum (the one in the photo above is titanium). But even when most road bikes were made of steel, bent steel hangers were still a common problem. Luckily, most bikes today use replaceable derailleur hangers. They’re bolted on and can easily be replaced if they’re badly bent or broken. A good source is https://derailleurhanger.com/.
How To Tell If Your Hanger Is Bent
Two common signs that your hanger is bent are 1) suddenly the shifting is not working the way it was; and 2) the specific problems caused by a bent hanger are hesitation shifting into the smallest rear cog along with shifting over the largest cog and into the spokes.
Or, if it’s only bent a little, the derailleur might not throw the chain off the cog or into the spokes, but it might touch the spokes when you’re riding, making a tick, tick, tick noise as it hits each one.
If you experience these symptoms you should stop and visually check the hanger alignment. To do this, stand directly behind the bike kneeling or stooping so you can see the cassette cogs, derailleur pulleys and chain.
On a perfectly aligned hanger, an imaginary straight line will bisect the cog the chain is on and both derailleur pulleys. When a hanger is bent, that imaginary line won’t be straight. You can clearly see this in this photo from Park Tool’s page on derailleur hanger alignment.

Fixing It On The Road
Here are a few ways to fix or try to fix bent derailleur hangers on the road. I’m assuming that you didn’t shift into the spokes and break some and/or bend the derailleur itself. Or that you didn’t damage the dropout.
NOTE: Make sure the wheel is securely clamped or bolted in place before straightening derailleur hangers. The axle reinforces the frame so it’s safe from the bending forces. Before working on a bent hanger, shift the derailleur onto the smallest chainring and cog. This is best for sighting the alignment and it takes most of the tension off the chain.
Replace It
If you have a replaceable derailleur hanger, the best way to deal with a bent one when riding is to carry a spare hanger and simply replace the bent one. The part is so small and light you won’t even know you’re carrying it. Be sure to carry the right tools to remove and install the hanger.
Again, this assumes that the only thing damaged is the derailleur hanger. If you replace it and the shifting is still glitchy, then it’s likely that the derailleur also got bent, which is a different problem that’ll need to be addressed.
Straighten It By Hand
If you don’t have any tools (keep reading), you can try to straighten a bent hanger with your hand. The photo shows how to hold it. You want to pull out focusing on bending ONLY the hanger not any part of the derailleur.

Be very careful not to pull too hard at first. You might only need to move the hanger a small amount. Sight from behind, try pulling a little and look again to see if you improved the alignment. Then repeat until you’ve got the imaginary line bisecting the cogs and pulleys.
Use An Allen Wrench
In the photo I’m using a 3-way hex wrench inserted into the derailleur bolt. This gives a nice purchase and directs the straightening force exactly where it’s needed. A standard hex wrench will work too, but the longer the better for the best leverage.

Use An Adjustable Wrench
If you carry a medium adjustable wrench, they provide excellent leverage for straightening bent hangers. But you must first remove the rear derailleur.
Be careful removing rear derailleurs after bending a hanger. If the threaded part of the hanger was damaged or if the derailleur bolt was bent, it can be difficult to remove the derailleur. If you force it, you might strip the threads on the hanger or even the derailleur.

While it might be easy to replace a replaceable hanger, it might not be so easy to replace a stripped derailleur bolt, which might mean needing to buy a whole new derailleur. To avoid this, if the bolt won’t turn easily, leave the derailleur in place until you can get home and better assess what the problem is and fix it.
Use A Wheel With A Threaded Axle
If you have a rear wheel with a threaded quick release axle, it’s likely that the axle thread is a standard 10mm thread, which is the same as what’s in derailleur hangers.
This means that you can use your wheel as an alignment tool. To do it, you must remove the rear derailleur. You can then remove your wheel quick release, screw the end of the axle into the hanger and hold onto the wheel using it as a giant lever to straighten the hanger. Be sure that the axle fully threads into the hanger. If it’s only held by a couple of threads it’ll probably pull out (strip) the hanger threads – so don’t use the wheel.
Note that with this technique the wheel isn’t in the frame reinforcing it anymore. So you must be careful not to bend anything other than the hanger. If you’re riding with someone maybe they’ll let you put their wheel in your frame while you make the repair.
If You Can’t Straighten The Hanger On The Road
As long as the wheel and frame wasn’t damaged, you can usually get home with a bent derailleur hanger. Just remember not to shift into the largest cog. Since the hanger is bent the chain might make a chattering noise on the misaligned pulleys but you can usually find gears that align the chain enough that it isn’t so bad you can’t keep riding.
Next week, I’ll show you my favorite professional hanger alignment tool and how it’s used. In the meantime, please share your favorite on-the-road alignment tips and tricks. Also, here’s Park Tool’s excellent article on hanger alignment using their tool: https://www.parktool.com/en-us/blog/repair-help/rear-derailleur-hanger-alignment.
Jim Langley is RBR’s Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his “cycling aficionado” website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim’s cycling streak ended in February 2022 with a total of 10,269 consecutive daily rides (28 years, 1 month and 11 days of never missing a ride). Click to read Jim’s full bio.
The only additional info which I have to share is:
1) When trying to bend the hanger by grabbing the derailleur and pulley/jockey wheel assembly, gloves (I carry a thin rubber pair that take up no room and weigh nothing) prevent a messy/greasy hand and transfer of same to the bar tape.
2) If, in trying to straighten the DR hanger, one damages the threads in the hanger where the DR threads into it, I have been able to straighten the threads enough to reattach the DR by using the QR axle or even the bolt which attaches the DR to the hanger by threading either through the DR hanger from the backside (this may require removal of the DR hanger first). This process can also work for damaged crank arm threads (when pedals will no longer screw in properly (thread the pedals in from the back side to straighten the threads) or for many other damaged female threads.
Thanks for the great tips, Walt!
Jim
Jim is missing one very important point. Even hangers made of aluminum are not all the same. In some cases, my Pinarello for example, the aluminum is brittle and will snap off rather than bend. In other cases, my friend’s Specialized for example the hanger is pliable and can be straightened quite readily. So I would say, never try to straighten a hanger unless you are prepared for it to break. This means having a replacement on hand. And if a bike is rideable never mess with it by the roadside, again, unless you have that replacement with you
Roger
Thanks, Roger. If a piece of aluminum is bent far enough, when you try to bend it back it can break. Most hanger bends are not that severe luckily and they won’t break if it’s a slight bend you’re fixing.
But, it’s a good point that if you were to crash hard enough or shift into the spokes and bend your aluminum hanger at an extreme angle it would likely break if you tried to bend it that far back. I mention in the article that it’s smart to carry the right replacement hanger for your bike if you have a replaceable hanger.
Thanks,
Jim
Like you, I have a hanger on my road bike that cannot be straightened. Seems like even the lightest niche to straightened and it breaks.
I always carry a spare hanger. On the road or retail is much winner y to replace the hanger than to try to straighten it.
Before attempting to remove derailleur hanger small screws always clean out the screw head with a pin or sharp pointed tool.. These screws are often loctited in or slightly bent and you’ll need your Allen key to get in as deeply as possible.
This tip also applies to cleat screws particularly.
Thanks PHILIP, that’s a great tip!
Jim
Something I don’t see mentioned here relates to why the hanger bends. In the days of metal frames, if you had a heavy impact on the derailleur, you could bend the frame. A metal frame can be straightened. With many of today’s bikes being carbon, the carbon will not bend, but it will crack. By changing the hanger to aluminum, you make that the weakest part of the assembly. When the derailleur gets hit, the hanger bends to absorb the shock and save the frame.
Yes, that’s a good point, Big Ring Bob. The nice thing about the steel hangers on steel frames is that they’re much less likely to bend in the first place. Plus, even if they get bent badly you can usually bend them back and though weakened by the trauma they usually hang in there just fine. Even though they are easily replaced, you could argue that aluminum hangers are one of the liabilities of carbon bikes since they bend so easily.
Jim
The Wolf Tooth Pack Hanger Alignment Tool has been useful for me. We arrived on our first trip with our CoMotion S&S coupled tandem to find the hanger was bent in transit. I did not have the tool at the time and we were fortunate to find a bike shop that could help us after a 20 minute jog to arrive before they closed. I’ve since decided to pack the tool with the bike and to remove the derailleur and hanger when I pack the bike. Even so, the tool has been used a few times mid-tour to tweak the alignment.
I have no financial interest in Wolf Tooth; I’m just a satisfied customer.
Thanks, Peter. I reviewed the Wolf Tooth alignment tool and did a video on it, too. Here’s a link to both:
https://www.roadbikerider.com/wolf-tooth-pack-hanger-tool-review/
Good tip!
Jim
Love these “how to” articles Jim.
From my experience, you can straighten a bent Derailleur but it weakens the hanger. Best to replace it as soon as possible. Aftermarket replacements are usually readily available online. They are cheap. Order two, keep one as a spare.
Thanks, Steve! I gave a source for find and buying the right hanger for your bike in the article and also recommend carrying a spare with you.
Jim
I recorded a (now very old) YouTube video taking Jim’s tip about threading a spare wheel into the hanger a couple of steps further. I describe how you can use that wheel not just to leverage the straightening of the hanger, but also as a fairly accurate realignment gauge.
Here’s the link for anyone interested: https://youtu.be/T45tsSjyjDA
Thanks a lot for sharing your video, Kevin – very helpful!
Jim