Technical Tuesday: Straightening Your Derailleur Hanger

Aug 3, 2010 at 0:07
Aug 3, 2010
by Mike Levy  
 
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Your bike can shift poorly for a lot of reasons, one of them being a bent derailleur hanger. Today's Tech Tuesday shows you how to fix this common problem and get your ride's shifting back up to par. Inside you can watch a great video guiding you through the process from start to finish.

Read on...

There are plenty of reasons why your rear shifting may have gone haywire, but one of the more common ones is that your bike is suffering from a bent derailleur hanger. I wouldn't think of this as it being "broken" per say, as the job of a replaceable derailleur hanger is to absorb abuse (bend or even snap if need be) so that your derailleur or frame are spared. The hangers are made to be weaker than the actual derailleur that attaches to them for this very reason. A bent hanger can happen quite easily, although a simple way to limit the chances of having to do this repair is to simply avoid laying your bike down or against anything on its driveside. I can't count how many times I've seen bikes bouncing up and down on their driveside as the shuttle truck makes its way up a rough road.

Before starting this repair it is important to note the differences in derailleur hanger types. The most common design is the simple bolt on hanger that is held in place by one or two bolts. If they do snap they are usually the most inexpensive type to replace. Some full suspension bikes (and a few hardtails) use a larger unit that encompasses both the dropout and derailleur hanger and bolts to the rear stays. This can make for a stiffer interface as the hanger is built into the dropout and may result in better shifting for that reason, especially when using the latest 10 speed gearing. The downside is that this piece is likely to be far more expensive than the simpler common bolt on hanger. The last type is the much less common non-replaceable hanger. While it can make for precise shifting, the consequences are high if you manage to severely damage it. This type is far less common and I'd recommend taking it to a professional shop to have it straightened if you manage to bend yours. Regardless of the type of hanger that your bike has, they all use the same technique to straighten and I can't stress enough that you need to be gentle and take your time throughout the repair. Spending an extra ten minutes doing this job may end up saving you money and downtime. Like a lot of repairs, this one requires special tools and if you don't have them, or don't feel comfortable doing the work, take the bike to your local shop to have them do the work.


Tools needed: Hanger Alignment Gauge, 5 mm allen key

Watch the video to learn how to straighten your derailleur hanger

Views: 64,883    Faves: 50    Comments: 15





Past Tech Tuesdays:

Technical Tuesday #1 - How to change a tube.
Technical Tuesday #2 - How to set up your SRAM rear derailleur
Technical Tuesday #3 - How to remove and install pedals
Technical Tuesday #4 - How To Bleed Your Avid Elixir Brakes
Technical Tuesday #5 - How To Check And Adjust Your Headset
Technical Tuesday #6 - How To Fix A Broken Chain
Technical Tuesday #7 - Tubeless Conversion
Technical Tuesday #8 - Chain Wear
Technical Tuesday #9 - SRAM Shift Cable Replacement
Technical Tuesday #10 - Removing And Installing a Headset
Technical Tuesday #11 - Chain Lube Explained
Technical Tuesday #12 - RockShox Totem and Lyric Mission Control Damper Mod
Technical Tuesday #13 - Shimano XT Crank and Bottom Bracket Installation

Have you found this tutorial helpful? Share any of your hints or tips below!

Visit Parktool.com to see their entire lineup of tools and lubes.
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75 Comments

  • + 9
 wow that was super useless advice. Only purpose it serves is to advertise "hey look park tools sells another over priced tool to adjust your $3 derailleur hanger! And don't attempt to do this unless you buy it!"

Even the video admits you can use the derailleur cage to check the alignment, therefore there is no point in having that unpractical tool to check alignment using your rim as reference.

I'm surprised he didn't mention to make sure the rim is straight, you must also buy a parktools truing stand and spoke wrench prior to using this tool
  • + 7
 the only thing i can't agree is this $3 hanger. hangers for some bikes are $20+, not to mention dropout+hanger pieces.
  • - 4
flag lafalot (Aug 3, 2010 at 2:35) (Below Threshold)
 yes you are correct many do cost more, however those ones are usually the better aftermarket ones that are CNC'ed from higher grade aluminum or steel - these rarely bend. The ones that bend the easiest are those cheap forged alloy ones found stock on low level spec bikes. Those are so soft you can bend them back by yanking on your derailleur to straighten it haha, and those are a few dollars to replace because they are also sold in bulk due to so many lower end bikes being sold, and very often with a "universal" hanger size.
  • + 3
 try $50 for a session 77 hanger!!!!
  • + 4
 @ lafalot

The reason hangers bend is to prevent the bending of your derailleur, which unless you're still running alivio is by far more costly than replacing you hanger.
  • + 7
 Lafalot,

Having straightened hundreds of hangers over the years I know that simply sighting from behind doesn't cut it 90% of the time when trying to get everything aligned correctly. My reference to looking from behind is only to see if things are out of whack, but I can't count how many times that a hanger was only out a touch, not enough to straighten with just your eyes, but enough to hinder shifting. A hanger alignment tool is the right tool for the job, no matter if its a Park model or from another less expensive brand. This is especially true now that more and more bikes are shipping with 10 speed and tolerances need to be even tighter.

Regarding mentioning if your rim is straight... If you use the same spot on the rim, I used the valve stem for reference, it does not matter if your wheel is true or in dish. Just I say in the video, rotate the rim with the tool.
  • + 7
 I don't doubt your experience as a bike mechanic, and I agree from a professional standpoint this tool does it job. However from a practical standpoint, I have a problem with the level of "advice" that is really given by such a video. You basically said we have 2 choices:

1. Get an expensive tool to fix the hanger
2. Take it to the shop

You never mentioned how cheap it would be to get a new hanger (which you install yourself easily) vs. buying the tool or paying someone to use the tool to fix it. I can tell you most people are not going to buy that tool, which only leaves #2. So then where's the real useable advice?

If this video was directed at mechanics, I can see the importance of the tool, but again they will already know this. If it was directed at road or XC racers demanding the best out of their 10/11 spd drive trains, I can also see the importance of the tool, but again, they will already know to take it to the shop.

Which leaves the average young male on pinkbike beating around on their mtb for fun with a dirty cassette, probably a chain that's too long, and mashing gears - all the while still enjoying their bike and have it work well enough to have fun! They won't find this advice helpful at all.. they will continue to use sticks or hammers to fix their hangers.

Maybe if you renamed the title to "how a shop mechanic straightens out your derailleur hanger" it would be more suitable for the majority of us.
  • + 1
 hangers arent always cheap. $50 for one for me!!
agreed on everything else though
  • + 1
 try ebay my friend. But I would vouch that many of the expensive hangers are built pretty tough, and if you manage to bend one, it wouldn't be a good idea to bend it back. In fact I more or less agree with m47h13u that mentioned bent hangers in general should just be replaced, not fixed as a metal that has been stressed past its yield strength won't likely last very long anyways. Most of us aren't going to be repairing enough hangers to make the tool worthwhile, so why pay a shop to fix your old hanger (and possibly have it break soon anyways) instead of just getting a new one and putting it on yourself?
  • + 1
 ye checked ebay, cheapest was £38 incl postage from israel - pretty much $50
  • + 2
 if its one of those one piece hanger and bolt on dropouts like on your session 77, I'd spend the $50 than risk bending it back. If the metal is badly stressed you could suffer from more serious consequences compared to a separate hanger and dropout system anyways so better safe than sorry right.
  • + 1
 good point. cheers tup
  • + 1
 You can't sight straighten a hanger for the simple fact that it has to be aligned on 2 axes, from the back looking along the length of the bike and the twist of the derailleur when looking down from above the derailleur. Furthermore to get it to shift perfectly the hanger must be dead on balls accurate. There isn't anything truly straight on most frames to visually align a hanger to, so in all likelihood what you think is straight really isn't. And what you end up doing is bending the hanger back and forth a bunch of times as you keep over correcting your bends by hand which ends up weakening it to the point that if anything touches it again it goes out of line once again.
  • + 1
 No amount of "professional" straightening is going to be as good as a new hanger, so if you want perfection, straightening isn't the solution anyways. If anyone bends their hanger, they should bend it back by hand, if that doesn't work, get a new one. It doesn't need to be so complicated. Only time a professional tool is a good idea is frames without replaceable hangers, which are few.
  • + 1
 My hanger is worth 12$, my derailleur 80$. The hanger bends easily but that's its job, it prevents the derailleur from getting wrecked. Why the hell would I buy a sturdy hanger, so it destroys the 80$ derailleur instead of the 12$ hanger? I like my hangers flimsy. Even if you change 2-3 hangers during your season you're still not even halfway to what it would cost to replace 1 rear derailleur.
  • + 1
 pretty sure if you're bending your hanger, you've already bent if not broken you derailleur clean off
  • + 1
 Actually, a lot of hangers are made of relatively weak alu so it can bend before your derailleur (or your frame) bends. It's a safety and it worked many times for me... Crazy bend in the hanger but when you change it the derailleur still works perfectly. My cousin's derailleur is mounted directly on the frame, every time he hits it somewhat hard, it's fubar.
  • + 1
 Guess I just ride too hard
  • + 2
 Or you fall too hard.
  • + 8
 another good vid. although he is basically saying, if you dont have the tool, dont do it yourself. and really, who has one of those massive tools lying around? so maybe next time give an alternative for the average rider who doesnt have the tool.
  • + 1
 that's exactly what I was thinking.
  • + 1
 Easy Way: Park Tool DAG (Derailleur Alignment Gauge)
Hard Way: Adjustable wrench

It's a pretty easy method to figure out.
  • + 1
 i already know how to do it without the tool. i was just saying that it would be helpful to others if they showed an alternative way. like they did in the measuring chain stretch episode.
  • + 0
 same here, i always used adjustable wrench.
@seraph: pretty easy just for some of us.
  • + 1
 Tech Tuesdays are now sponsored by Park Tools. Brule confirmed it last week's video. We had a discussion about it in the comments. They should probably put it in the article heading, but the t-shirt should give it away.
  • + 1
 Yeah, I want the DAG but it's like $60 for something you'd only use once every few months.
  • + 4
 too bad that for example a simple park tools metal saw costs like 6-7 times more than a typical (still doing its job) saw you can buy in a hardware store. or digital caliper - over 4 times more than in a hardware store. park has tools that you can't buy in a hardware store, but I WONDER how much overpriced they are. i'm not hating, just saying.
  • + 2
 The answer is VERY overpriced. Thats why I use non park tools for just about everything except specialty. i.e. bottom bracket tools, cassete tools, ect. Everything else, cable cutters, screwdrivers, allen's .....can often be subsituted. The Park quality is quite good, Im not saying that, but there are other quality tools on the market that come in under the price of the park stuff.
  • + 3
 I've got a better way to fix a bent hanger. Replace it, there is no use in trying to re-align a hanger as it has suffered elastic deformation. When any piece reaches this point they often don't last long to begin with so why risk losing/damaging parts more.
  • + 3
 Not that I don't appreciate "how to's" but this a ridiculous video. If you've bought this tool you'd have to be an idiot not to know how to use it. An easy and effective "ghetto" straightening can be done with a length of threaded rod M10 x 1.0 (a bicycle axle!) Thread it in to the hanger and you've got an excellent indicator and lever and you'd be hard pressed to find anyone with a bike that doesn't have an old axle kicking around.
  • + 3
 These tech tuesday vids are getting better and better. Why all the hate on Park tools? They DO have the widest selection and highest quality tools for getting specialized work done in my opinion. Spend $2,000 on a frame and allow some bike shop stoner to bend it back in a vice?? no thanks
  • + 2
 This tool is indespensible when fixing steel bikes without replacable hangers - and every good shop should have one. Not so sure it's something the home mechanic has. The video was accurate, but bending back a cheap cast aluminum hanger will fatigue it and it will eventually snap - and likely when you least desire. It's best to just replace these ones. The more substantial hangers can be bent back but it's more likely they will break before they bend so you won't have any choice. The lesson here is how to identify that your hanger is bent. Replace the cheap ones and hope for the best with the others, but let a shop do it. It's a much cheaper option than re-spoking your wheel since this is where the chain usually goes when the hanger is bent. Sometimes you can't cheap out. The other option is to go single speed.
  • + 3
 Whether you have access to a DAG, simply KNOWING that a bent derailler could be the cause of your shifting problems is worth a lot, regardless of what you do with that information.
  • + 2
 the last time my rear hanger got bent in a trail, i placed it under a flat piece of wood and jumped on it a couple of times. worked for me temporarily. lol. now i know how to get it done, with an expensive tool that I would never buy.
  • + 6
 singlespeed !
  • + 3
 yes. Smile
  • + 2
 I try to fix everything myself but i usually run into problems with the d hanger. First off i dont know where it is? So i never know if its bent. I just keep riding till something falls off then i know whats broken.
  • + 1
 not expensive to replace? I snapped my derailleur hanger 5 times and each time i had to pay around 20$. Then i converted my bike to a single speed, and month later my bike got stolen. Now i got a new single speed bike and i'm fukin happy!!! Beer
  • + 1
 Higher end Giants (say anything with SLX or 105 or higher on it) come with a free derailler hanger - if you just bought a Trance X3 and didn't get a spare derailler hanger - ask for it.
  • + 1
 Try £50 for a commencal meta sx hanger! That is a real stinger when my zee clutch mech is less at £46 where is the sense in that...and yes I have tried Ebay. They do every other model bar mine....typical.
  • + 1
 I was thinking more along the lines of putting the hanger inbetween two pieces of wood and hitting it with a mallet... Should work out fine
  • + 1
 It makes just sense to use this tool, if you've an frame WITHOUT an exchangeable drop-out. An fixed drop-out will crack much faster than an new spare one.
  • + 1
 www.outsideoutfitters.com/p-10730-park-tool-derailleur-hanger-alignment-gauge.aspx
Not a bad investment at this price, cost just 2.5 hangers.
  • + 4
 allway usefull
  • + 3
 Also if you make sure your wheel is completely true, check the alignment round the whole wheel first to see which way it's bent, it can be twisted too, you only want to bend it back as little as possible.
  • + 2
 Yery useful, Be careful after fixing your derailer hanger because the last one i bent snapped 5 mins into a ride after i'd fixed it.
  • + 12
 interesting, but beneficial???
for the price of the tool how many hanger could just go out and buy??
  • + 2
 Very true.
  • + 2
 I still think this was a nifty tech tues. This is a usefull tool if you have one. I dont, I use an adjustable and my eye to straghten things out, or I replace. But I have run into situations where the derail looks ok, but there is a shift concearn and I would like to check the alignment more carefully. Especially on a bike where replacing the hanger is more than three bucks. This is a bike shop tool, but its good to know it exists, and how it is used.
  • + 2
 nice guys...
  • + 5
 doug13 as long as your taking the reading from one place on the wheel (the valve) it does not matter if your wheel is bent or not because you are getting the same dish all the way around
  • + 2
 True, it's just a bit easier to check for twisting, and you should have true wheels anyway!
  • + 1
 lol, Hanger Alignment Gauge? i use normal old rear wheel with long axle and I screw in to hanger and easly i can do this...
  • + 1
 at the end of the tech thus you will collect whole park tool productline Big Grin
  • + 1
 Most times it's an easy fix but it's always good to carry few spare parts in case you want to hot-swap and continue riding.
  • + 1
 this episode of tech tuesday fails!
  • + 0
 you can always just stick a long 5mm wrench into the derailleur bolt and bend away.
  • + 2
 to which direction?
  • + 1
 This tool costs £70 on ChainReactionCycles.
  • + 1
 Nice Bike Mate Smile
  • + 1
 sweet
  • + 1
 Good info, thanks!
  • + 1
 or use a vice , way easy
  • - 1
 Or you could be a hack and hammer it straight. lol
  • + 0
 woah GGGAA jk sick man
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