How To Straighten A Bent Rear Mech Hanger | Maintenance Monday
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- เผยแพร่เมื่อ 23 ก.ค. 2024
- Your rear mech is one of the most vulnerable parts of your bike. Crashing your bike or knocking it while moving can cause your rear derailleur to hang at an angle and wreak havoc on your gearing. Don’t worry though if this has happened to you as it's easy to fix, and Manon will show you how!
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What other maintenance tips would you like us to cover next?
At the very end Manon says 'you might want to index your gears'. How about a tutorial on that? Everything's better with Manon.
Getting headset bearings under the perfect load settings, it's always a tricky one and often ends in pitted bearings a few months later (quite often).
Any tips would be great, as the issues it can cause can affect the whole balance of the bike.
I was under the impression that for a carbon frame, you’re supposed to remove the bent hanger and straighten it in a vise. The reason is supposedly to reduce the stress on the dropout from bending a metal hanger. The tool is only for fine tuning and checking. For a steel frame the hanger is part of the dropout so you just bend it and it is strong enough for that.
Is this the method recommended by CF frame manufacturers now?
Awesome. How to fix a wheel spoke that is rubbing against the disk brake caliper ? Just one pair of spokes. The other ones are good.
#askgcntech hi chaps and Mannon. Thanks for all the advice so far really enjoy the show. I have recently bought a road bike with aero handlebars. I now need to look for a suitable front light to fit… there are many “bodged” solutions , what would you suggest to securely fit a front light to aero handle bars? Thanks, Ed
The measurement should be taken using the valve stem as a referernce point at all check points (ie. 12 oclock, 6 oclock). Doing this takes wheel truness and dishing out of the equation.
Incredibly useful advice, specially for bikes where the wheel will most likely be out of alignment like MTB, BMX or cargo bikes
You should turn the wheel so that you're measuring against the same part of it at each quadrant. This eliminates any errors introduced by a out of true wheel.
Yup. Park Tool recommends using the valve stem as a reference spot.
Valve following is really important. Also easier to get derailleur back in with a slack chain - small chain ring etc. I've found that even brand new mech hangers need checking.
If your wheel is out by more than 0.5 mm, fix that first. If the hanger is within a millimetre or two, it's fine.
Pro tip from a Cyclocross racer: buy a spare hanger (or two, or 3 depending on your discipline) and just replace it when bent. Then use your spare time on a rainy day to fix your bent hangers so you have one at the ready just in case. The adjustable wrench method can work great in combo with a bench vice and straight edge to straighten a hanger off the bike too.
Buy a new hanger and replace NOW with your multitool, keep the old one in your saddlebag. If you need to change it in the field you know the spare fits and your multitool will do the job.
Agreed. They are inexpensive relative to everything else on your bike.
Not all hangers are planar, or even designed flat enough to get a straight edge off, and not all hanger pockets are perfectly in line with the plane of the wheel. You should always adjust the hanger to the frame, not rely on a theoretical alignment.
@@zygmuntthecacaokakistocrat6589 In most cases, new hangers that were never realigned can still have the rear derailleurs shifting OK, not misaligned enough to make indexing impossible.
Although it's most ideal to realign it, which isn't possible when you're out riding with a spare replacing the other hanger.
Estaría buena tú idea, si no fuera por que las campanas no coinciden bien.
I finally got my head round a lot of bike repairs in lockdown with the help of GCN. Another great vid.
Likewise
About 25 years ago I had a bent rear mech hanger on my beautiful Eddy Merckx frame. I took it to the local frame builders and they used a blowtorch on it to soften up the hanger and then bent it the same way as in this video. But I did need to respray the frame, and I had it an amazing banana yellow with black writing that bike looked really cool after that.
It can work in a pinch, personally, specially if it was bent pretty bad, I would just replace it. Those hangers are cheap, and a derailleur in the spokes because the hanger had metal fatigue/cracking from bending and then shearing off due to vibrations over time tends to be more expensive. To get home, or to get to work the next days it's a good solution, but considering the price of the part, and usually the price of the parts around it that it could mess up I wouldn't risk it long term, specially as you might bend it again at some point, and bend it back again making metal fatigue an even bigger risk.
My friend was having poor shifting, hanger looked bent. So we tried to bend it back but it instantly snapped.
And his screws were stripped and we couldn't remove it lol.
Crazy night. Lucky we were already back at school, I learnt a long time ago, that if it's not the brakes or a puncture don't try and fix it until you're where all the tools are.
Easy to make your own tool. I use a bolt that fits the hangar, through an old office table leg 1" box section steel. With a spacer and just Measure.
This!!! Things that fit the thread: threaded rear axles, rear wheels with cup&cone bearings. Another DIY method: screw an M10x1 threaded rod into the hanger, clamp another rod into the dropouts. Eyeball and bend until rods are parallel.
Every time I watch these repair vids, I learn about a new tool from Park Tools!
Great video! Some wheels have a threaded part just as the same as the hanger. So thread that in and you can use a measuring tape to adjust a bit more precise and not want to buy the special tool
Excellent vid and couldn't have come at a better time because out riding this morning, I fell and bent my rear mec. So, cheers for the info.
Thanks, Manon, for sharing the knowhow. The explanation was clear and to-the-point.
Glad you found it helpful
Well explained! Thanks for the tips with different and no tools.
I think the adjustable spanner is horrible advice. It's impossible to get it right by eyeballing. It's easy to jury rig a much more precise hanger alignment tool.
This is the most adorable repair video I have watched so far
"if you have bent your mech hanger you'll
be able to see just by looking at it"
Yes, if it's severely bent, it'll be visible to the naked eye. But 11 and 12 speed derailleurs require very precise hanger alignment, and can shift inaccurately even though the bend is so slight as to not be noticeable.
This was super helpful, thanks so much! I had to use the poor man’s method but it ended up working great 😎
Thanks, Mannon! While not perfect I was able to follow along and bend it back in place until I can get into the shop.
Thank you so much for this fantastic video. I hope it helps many people. I had a bike accident a few weeks ago and initially thought I was fine. However, the derailleur hanger snapped while riding, and I had to replace it, which cost $1,200.
Thank you so much Manon, I tried it and fixed it.
Really clear and helpful video. Thanks.
You're welcome!
I'm going to attempt this tomorrow so I'm studying up on TH-cam. I found your vid very helpful.
Helped me! Thanks.
I just love to see Manon
Before attempting to correct anything I would suggest taking the first measurment and rotate the wheel to ensure its true. You could be trying to fix something that's not broken.
Thanks Manon!!👍
Good explanation Manon
@ 1:15 Dearest (other) GCN presenters, that's how you present stuff.
so stoked to be the first! i love all your videos and input GCN! I would love someday to get my own road or gravel bike. I'm keeping watching your vids to learn! Thank you for all your knowledge!
Thank you: I thought I would have to throw my new bike in the dump, but now I know it can be fixed. Very useful.
Nice tips..! GCN
Tankx Manon, I had my first crash of the year , I was at a stop light ready to make a left on a green light when all of a sudden I fell over on the drive side. I mean I never even tried to take my foot outta the pedal I just fell over, the car behind me asked if I was Ok . I was more embarrassed then hurt so then the light changed I was happy to cross the road without farther incident. On the bright side I didn't bend the rear mech hanger.
Great job Manon!💯👏🏼👏🏼👏🏼
I just use your vid to realign my mech hanger. 🥰
Oh and,, Alex you really should be more careful with such a beautiful bike. 😉
Thanks Manon
Manon so cute🥰
With some supply shortages, I make sure I've got a spare hanger for my bikes. Having said that, I've used a shifting spanner to straighten a few hangers too. Thanks GCN.
#askgcntech hi chaps and Mannon. Thanks for all the advice so far really enjoy the show. I have recently bought a road bike with aero handlebars. I now need to look for a suitable front light to fit… there are many “bodged” solutions , what would you suggest to securely fit a front light to aero handle bars? Thanks, Ed
As a mountain biker always took a longish 5mm allen key to bend it back on the trail. Put key in the hanger bolt and bend away.
Great video, a derailleur alignment tool is priceless. Two more tips: first, when reinstalling the rear derailleur, be careful the b-screw clears the stop on the hanger; second, if you're stuck in the wilderness w/a bent derailleur, with the rear derailleur in place, use an allen key in the mounting bolt as a lever to gently torque the whole assembly back to roughly where it should be. Fantastic content GCN.
Well, it's about 100 quid but who's counting?
@@zygmuntthecacaokakistocrat6589 True, it's not an inexpensive tool - good ones are not cheap; but I've got 5 bikes and accounting for the amount of time it saves in sorting out bad shifting, it has paid for itself 10X over.
@@edwardsjohnpaul or spend 5 pound on a new hanger and the problem goes away I got 95 pound for beer.
Another hack: if you have someone with you who has a conventional M10 x 1 axled rear wheel hub you can thread the stub of their QR axle into the derailleur hanger (same thread) & use the whole wheel as a hanger aligner! Easy to see errors with the wheel as the gauge!
I always tell people I do this for (with a proper hanger aligner) that there's a 30% chance that the hanger will crack in the process of straightening, especially if it's been badly bent. The feeling of the hanger cracking and separating when this happens is very dispiriting. & why are there so many different types of hanger that take ages to source and order?
I know this is an advert for that Park alignment tool although I can say first hand that it's a pretty amazing alignment tool
Manon's method assumes that the wheel is perfectly true, which rear wheels rarely are, especially after a shunt. The better technique is to rotate the wheel with the alignment tool, so that you are measuring against the same spot on the wheel. The valve makes a consistent marker. Put the valve at 6:00, take your measurement, rotate the wheel so that the valve is at 12:00, take the 12:00 measurement, etc., etc..
i watched this clip twice coz i was mesmerized by the dragon queen of wales when i first watched this. manon is so beautiful.
1:19 The "The Price Is Right" look is price-less!
Always a good idea to have a correct spare hanger for the specific bike added in with the puncture / toolkit. A lot cheaper than being stuck having to take a taxi home or burning up brownie points with the other half by using them as a recovery service.
Depends on the size of the toolkit you always carry. I'd have the spare hanger at home to save those few days it takes for a replacement to arrive.
Thanks
Is it advisable to do this straightening on a carbon frame? I'd be afraid of cracking the frame insead of bending the hanger as intended. Is there any alternative?
I see Manon, I immediately click and like.
Thanks Manon...mmm , ok . I am someone that has snapped and bent hangers , how many adjustments are the hangers rated for . ?? I would change the hanger ASAP , to be confident ? I have been stranded in the woods after it broke , and it wasn't good
There are a lot of variables: No. of blows taken, force of the blow taken, type of metal used, etc. So there's no definite answer. Some are as soft as tofu (Pinarello), while others are pretty beefy (one BMC Teammachine ALR Disc I worked on).
Even if you use a new hanger, it's not always 100% aligned. Just because a hanger is straight on its own, doesn't mean it'll be aligned when installed.
I do not have an alignment tool, but I do have a spanner and allen key. I also have a bike stand which my bike has been clamped into for some time using the frame 😬
So sweet, Manon thinking I have Di2. ❤
In a future, maybe, as I just got new wheels with the groupset of the people.
Edit: about the being on the road thing. Bring a spare mech hanger in your kit. This is the first thing I got with the new bike, 2 in fact. One is kept in my bits box at home, the other one in my saddle bag with my spare tubes which I also hope I never have to use.
the thread of the hanger is the same M10 as the regular rear M10 qr axle, so if you don't have the alignment tool, but have one at hand and, it can show you how bent it is,. if you have a cone and a locknut on it, you can securely place the axle in the hanger, then use an old seatpost as leverage to straighten it.
My drive train is clicking my crank and BB are new could this be the cause?
So I cross threaded putting my derailleur back in because the inserting part of the derailleurs thread was bad. Will that come loose after a short while? What problem did I create for my self? Hope I can just keep it like that.
does it also work with a carbon frame?
The best bike hack ever: old school front wheel hubs have the same thread as rear mech. Pull off your derailleur but leave rear wheel installed and screw in front wheel (the whole wheel) into derailleur hanger. Then use front wheel to bend hanger until the front wheel and rear wheel are absolutely parallel. No special tools needed!
It's a M10 x 1mm thread, so it's a rear wheel QR axle thread.
If your gears are not shifting then checking alignment should be the first thing you do. If it is misaligned then adjusting the limit screw and the barrel adjuster will only make it worse. I found when I had to do this that you should bend the hanger by about half the measured gap. If instead, you bend enough to fully close the gap, then you will simply alternate between the hanger being misaligned in one direction or the other, but never get it straight.
Don’t forget to measure at the valve each time you turn the wheel each quarter in case the wheel isn’t perfectly straight.
Meh, unless your wheel is badly out of true, the discrepancy that the wheel contributes to the measurement is negligible. The hanger needs to be aligned to within 3 mm or so.
finally im early
love from philippines
Not all hangers are created equal. Some of the Chinese hangers are more of a cast aluminum and will snap in half when you try to bend them. Best to have a spare hanger on hand so if you have an issue just replace the hanger.
All quick-release rear wheel axles have the same thread as the derailleur hangers. After a fall, you can use a other rear wheel to check and adjust the rear derailleur hangers.
It is important that you always use the same points on the wheels to measure the distance, preferably the distance between the valves on both wheels: If there is an imbalance in the wheels, this can affect the measurement less.
MANNON!
What is the small wheel with the pink thing around it that part of mien is bent not the actual hangar
How many times can you bend it before it snaps off ? ! Mine is part of the drop out casting (steel frame), if it snaps, the frame is history !
It depends on the number of blows the hanger took, the force of the blow it took and the type of metal used.
I've realigned the integrated hanger of two steel bikes before (much like yours) and they do indeed require maximum hand sensitivity to be realigned carefully, bending bit by bit until it's OK.
For my realignment tolerances, I usually aim for
I honestly would used some direct heat on the derailleur hanger as that hanger is brittle and after a bend is introduced it will stretch the molecules on one side and shrink them on the other if u just bend back ur actually causing the molecules to become stretched and compressed which will have little tears in it the great thing about aluminum is that you can annheal it many times unlike steel which hardens when heat is applied but the application of heat will aline the molecules and stops the metal from breaking due to the bending back and forth
I have 2 spare hangers. Never managed to straighten the mild aluminium
I align it perfectly at 3 and 9 but it is off at 12 and 6. I correct the 12 and 6 and it becomes off at 3 and 9. Been playing this game for a very long time. What am I missing?
You should have turned the wheel along with the tool.
I'm pretty sure I won't need the Di2 shift tool 😂
I never attempt to straighten hangers or mechs any more. With 12 speed long cage MTB mechs they are very difficult to straighten so that they shift precisely again. Last year, I had a bent hanger, and we carefully measured a 0.6mm bend in it which was nearly impossible to see by eye. It wouldn't shift for toffee on my MTB no matter how many adjustments we made. I replaced it with a new one for £12 and it was perfect straight out of the box.
Is it a SRAM UDH hanger or something specific to your brand & model (and probably a few others)?
I view the hanger as a sacrificial part that protects the derailleur and the frame. If I bend one, I replace it. As most hangers are made of relatively soft aluminum, they recycle easily, with very little energy cost.
Was reconfiguring my RD and realised my hanger wasn't straight-tried bending it from the RD but no luck, will try the wrench next. Did think about replacing but can't be bothered yet. The misalignment causes jumps on certain sprockets while pedaling, if anyone was wondering
No bike shop around you has a hanger alignment gauge?
@@yonglingng5640 Nobody close enough I think, it's all good. Thanks for asking!
Another tip: the bike should be horizontal, I.e. as if it were on level ground. Otherwise you’ll be adjusting the hanger in the wrong planes even if you are following the clock dial approach
That's what my colleagues don't do (and they're in the industry longer than I am!).
❤️❤️❤️
I have a frame which has less stiffness of its rear end. So then, my aligning tool is easily wobbled by its own weight. The value of accurate alignment is less than just using DI2.
I’d say the derailleur hanger is there to protect the frame, not the derailleur. The last thing you want is for the frame to be trashed. Derailleurs are expendable !
And for that, I insist on not running direct-mount hangers. Let the hanger fail so my rear derailleur and frame don't have to.
I screw an axle into the hanger then place the other wheel onto the axle. Then I bend the hanger until the two wheels are parallel to each other.
Unfortunately, this procedure is not correct. The error Manon is measuring could be a wheel out of true. To check derailleur hanger alignment, you must measure a fixed point on the wheel at different orientations. It is easiest to measure at the valve stem for reference, rotating the wheel to see where it deviates from the center line.
Came for the tips, stayed for the b-role
It is generally recommended to adjust lateral first, then vertical. And to take measurements against the same point on the wheel every time (usually by the valve stem).
And, given that aluminum is not ductile, better to make as few adjustments as possible - not overshooting in one direction then moving in another direction.
Now I feel like an ogre for eyeballing it and bending it by gripping the derailleur itself with my bare hands :) worked though !
More importantly it protect the frame , once destroyed a frame by ripping a derailleur of the frame
Love the video. Hate the lighting.
Well that was a missed opportunity for a ring close-up. OH, the hanger thing, right.
How hard is it to just replace a mech hanger? Aren't they just around $10-$15?
The price point is one thing, finding a matching one is another, especially if your bike is old or relatively unknown (or worse, both).
You can use your front wheel instead of a alignment tool. It should use the same thread. Shows you all you need to know about where the mech is bent to. Saving you money in equip.
I used a rear axle from an old shimano cup and cone hub. I mounted that axle to surface of a blank of wood with 3 screws. Because wood screws had countersink heads and I placed them close to axle in angle too. I could get any play removed and also the axle to right angle with the edge of wood. One screw is middle of axle in one side of axle and other 2 other side. So with single screw I can remove play and then with other 2 to get the angle right. Just measure the distance between wheel and blank and then rotate the blank 180 degree and measure it again. If distance is same, then the axle is 90 degree angle with blank. It's not super critical to have it 90 degree, but it's better. To bend the hanger you need to hold from axle not blank, because it's not strong and firm enough.. Although it was flimsy and took more time. I got my derailleur hanger straight very cheaply.. And the screws, blank and axle are still reusable for intended purpose too. And if I had to bring my bike to shop, or go to buy tools. It would have taken much longer.
Buy a park alignment tool 40+ plus pound new rear hanger 5-10pound 🤔
This is assuming your wheel is super straight! You should take the measurements to a reference point, as the valve, and turn the wheel to always have the same reference point (the valve).
Prettiest bike tech ever. Thanks
First thing I thought: Damn, I don't even have Di2. 😁
If you don't have one of those Di2 cable-unplugger tools, it may be that you don't don't even need one, especially if you don't have Di2.
Probably replacing the hanger is more economical than getting the tool and time to muck around.
👏👏👏🚴
Ok but my hangers snap if I land to hard off a drop, then the derailleur ends up on my spokes………….
If Manon is All-in-Black, means something went wrong . . . DEAD wrong!
Unless this is an old video, Manon is still wearing the engagement ring. Guys, we still have fantasizing mileage. 🤣🤣🤣🤣
How to straighten a bent rear mech hanger?
Install brand new rear mech hanger.
Toss old bent rear mech hanger in the trash bin.
Ta da!!!
Those eyes at 1:10… 😍🥵
🤣
Step 3, replace the hanger if you can get one. It's not as strong as it used to be. Everything is easier with top flite tools. For most it's not worth owning them. Riding fixed you'll never encounter this problem.
"first of here's the tools you're gonna need..."
Oh, we're in a different tax bracket