Jsendin

I have an alu frame where the right-hand rear drop-out is slightly bent inwards (to the left). It is the style that has a derailleur pad with two screws that connects to the frame. The bike was unable to make it onto the lowest gear at the back - if I adjusted the L screw then the derailleur would go it the wheel.

So I did a bit of a hack, whereby I put 2 very small washers between the pad and the rear drop-out. This had the effect of minimising the tilt of the derailleur pad inwards. This way I am able to get all the gears... but the indexing (predictably) is a bit off.

So a couple of options:

• Keep the hack job
• returning to the default and just never using the lowest gear (it has a granny gear anyhow)
• More radical option could be to bend the dropout straight, knowing full well that alu does not bend well... but it doesn't seem very bent does it?

Pics below show the misaligned derailleur pad before the hack job which straightened it somewhat

So my question is, is trying to bend it back a no-go?

Jsendin

Koyote

Take it to a shop, where they will use the proper tool to realign it with the least stress to the material.

Jsendin

Hey Koyote would that be something like this? Reckon, I may buy one myself as they are not excessively expensive

https://hollandbikeshop.com/fietsger...xoCySEQAvD_BwE

https://www.googleadservices.com/pag...BAgEEBI&adurl=

Hondo6

Pretty sure those are dropout alignment tools. They're used to make sure the dropout ends are parallel to one another.

To align a derailleur hanger, you'll need a hanger alignment tool like the Park Tool DAG-1, DAG-2.2, or DAG-3. I'm sure Cyclus makes one too, but I have no idea of its designation.

smd4

Yes, those are dropout alignment tools (and they are great quality, BTW). Cyclus makes this tool for aligning the hanger:

Cyclus Tools Rear Derailleur Hanger Alignment Tool | BIKE24

veganbikes

The dropout alignment tool is typically used on steel frames where things can sometimes be bent if things are out of alignment in the dropouts. You would need a hanger alignment gauge/tool but you would also want the knowledge on how to use it and to get a quality one. Just yanking on it could make things worse.

Here are the tools I would recommend for the job either one of these works and yes they cost money. I am not of the mindset of buying cheap tools because I am not a rich person so I don't have time for poor tools I want something that works and works well:
Abbey HAG
Shimano TL-RD11
Park Tool DAG-3
Park Tool DAG-2.2
EVT Ultra Tru Arc
Unior Hanger Genie

If you do not wish to own one of these tools and learn how to use it properly just go down to your local shop and see if they can align it or consider a new derailleur hanger. I would rather pay someone with the tools, time and knowledge on how to use them if I wasn't confident in my work or didn't want to buy the correct tool. That way I can get back to my life and let someone else do it. Time is money and cheap tools are a lot of money!

79pmooney

It looks to me like the dropout itself is bent also so that needs to be addressed also (and first since whatever you do to it will change the hanger alignment). Not straightening the dropout will have the effect of trying to bend and break the hub axle.

Getting both tools will put you in a good place for future bike repairs but we are talking quite a bit of money for tools you might need every 5 or 10 years. A shop's got then and will charge you maybe $50 bucks.

Another issue - this is aluminum. Aluminum doesn't like being bent and is prone to stress cracking and breaking in two at a random time later. You would be smart to have the dropout straightened by a good mechanic with a good touch (and still keep in the back of your mind that dropout has been compromised, The hanger should be a lot simpler. Ride this one only for as long as it take to find a replacement. A shop that carries your bike brand is your friend here. (And your micky-mouse hanger fix is probably superior to bending the hanger back in terms of the aluminum's remaining lifespan although a tough way to dial in an alignment that should be close to perfect for happy derailleurs and shifting.)

smd4

I'd have no qualms whatsoever about straightening the dropout (if it is indeed bent), and straightening that hanger.

dedhed

I'd align the dropouts with the old hanger, then replace the hanger and align that

Kontact 

Dropouts are somewhat hard, but you don't have a choice but to bend it back into shape. If it fails, then it was already smoked.

Hangers are soft aluminum and are designed to bend a bit more than once. If it doesn't crack, it's good until something bends or breaks it. Shifting doesn't stress the hanger much.


Having a soft touch and using those tools often are the best guarantees of success. Shops do not charge much for aligning hangers and dropouts.

Andrew R Stewart 

And I have no qualms about viewing a bent Al frame as a write off. Being such and knowing that a rear dropout "failure" is rarely a riding/control crisis I would also try bending things straight. I just wouldn't represent the repair as being a long term solution. Andy

Koyote

Post #3 is as good an answer as you're going to get:

Jsendin

Thanks all for the quick response and info

It seems I have conflated hangars and drop-outs ...probably cos I've worked almost exclusively on steel frames where this is often one thing

veganbikes thank you for the extensive list of recommended tools. I agree that cheap tools are expensive

Just watched Calvin Jones demo the Dag 2.2 - complete with him smashing a rear derailleur with a rock haha.

I am keen to own as many tools as possible but can see why folks are directing to bikeshop

Kontact 

Regardless of material or having a separate hanger, the two always need to be treated separately. Dropouts are straightened with tools that replace the hub. Hangars must be straightened with a hub rigidly holding the straight dropouts in place, or you'll just be tweaking the dropout when trying to straighten the hanger, and then the hanger will move with the wheel is put back in.

Generally speaking, if the dropout was flexible enough to bend in the first place, it will bend back. Old Klein aluminum dropouts were too heavy to bend.

pdlamb

It looks to me like the bend is in the rear of the dropout, not the derailer hanger itself. And that part of the frame looks pretty stout, even for being aluminum. Ergo, you're going to have to re-bend the aluminum dropout (behind the axle mount) to fix it, and deal with the possibility of the aluminum cracking as a result.

I think O.P.'s washer solution is elegant, and I'd be tempted to use it as is and to leave well enough alone. If you really want to, as recommended, get somebody else with tools and experience (your LBS) to fix it for you -- and keep your fingers crossed!

smd4

Why the thought that slightly bent aluminum will crack just by looking at it funny? Breaking news: Aluminum can be bent.

oldbobcat

Look at it this way. If you don't straighten it, it will just go on destroying rear hubs.

pdlamb

Depending on alloy and heat treatment ("tempering"), sure, aluminum can be bent. But thin, lightweight tubing the thickness of a beer can would not be a good idea to make a bike frame, unless it were tempered to be rigid. Problem is, that heat treatment also makes it brittle, so repeatedly bending it can make it break. And before you say "the dropout is thicker than a beer can" remember the heat treatment is normally done after welding on the frame is complete, thus the dropout has been heat treated to make it more rigid.

Ironfish653

because this is BeikForumz. Any Aluminum bike that has more than a blemish in the paint has been compromised and is an unrepairable accident waiting to happen.

Steel is Real!
How dare you question the Keepers of the Isoterica?

Kontact 

Aluminum frames aren't heat treated for increased hardness. Sometimes the tubes are from the manufacturer, like 7075.

dedhed

​​​​​​https://www.pinkbike.com/news/To-the...um-Frames.html

Kontact 

Congratulations on finding the newsworthy exception. The OP's frame was not hardened via heat treating. It was probably stress relieved - something Cannondale famously did not do in the '80s.

You are incorrect in saying that thin walled aluminum frames must be hardened. I rode an unhardened and probably not stress relieved Cannondale for 20 years.

Camilo

Back to the derailleur hanger - I think it's a good idea to have a spare on hand, just because. First, you might not be able to get one quickly when you need it. Second, although derailleur hangers can often be gently bent back into alignment, it's also pretty common for them to break during alignment. So get a new one for a spare or to replace the one that's bent. If you can't get one directly from the frame manufacturer, Wheels Manufacturing has a bunch of them, some for specific frames, some that are more generic and you have to match what you need with what they have (shape, number of attachments, etc.).

Mr. 66

I think it may be time to put that one out to pasture