Replaceable Rear Derailleur Hanger

**Batbike** · 03-02-2007, 05:52 AM

I have a carbon frame with an aluminum replaceable rear derailleur hanger. The hanger seems to easily get out of alignment because of the softer aluminum -- especially if I cross chain alot. Yep, I am really bad about using my 53 chainring with my last 3 cogs!

Anyway, use to have a steel and all aluminum frames, so hadn't had this problem before. Anyone else experience this issue? What do you do to keep from always needed to realign your rear derailleur hanger?!

**MontyBiker** · 03-13-2007, 05:28 AM

Originally Posted by Batbike

I have a carbon frame with an aluminum replaceable rear derailleur hanger. The hanger seems to easily get out of alignment because of the softer aluminum -- especially if I cross chain alot. Yep, I am really bad about using my 53 chainring with my last 3 cogs!

Anyway, use to have a steel and all aluminum frames, so hadn't had this problem before. Anyone else experience this issue? What do you do to keep from always needed to realign your rear derailleur hanger?!

Stop using bad gear combinations LOL

**DebW** · 03-13-2007, 07:39 AM

Just noticed a new Shimano rear derailleur, the Saint, with a new mounting system that supposedly attaches to the hub axle. Maybe it's a response to your problem.

**ridebikeme** · 03-15-2007, 05:09 AM

Ummmm... my suggestion is also to stop crosschaining... if you find that that is the gear combination that you are most comfortable with than perhaps you should change your cassette to accomodate that choice...or perhaps even change to a compact crank.

You didn't mention whether your bike is a double or triple, however the Saint hub would be quite a bit of work for a shop to set up. First, it's a mountain bike hub that is spaced differently than a road bike(mtn bike spacing is 135 and road is 130) . A shop could change this to accomodate your bike, but it's also a long cage derailleur...is that what you have on your bike now? If not, then the shifting will be quite a bit slower with more chain slap when you shift. The long cage derailleurs are setup for cassettes that are 27 tooth and up.. is yours in that range?

You mentioned that your derailleur hanger keeps bending ... have you replaced it each time that has happened? You can generally bend these back, but obviously they are not as strong as they once were...

Good luck with this!!

Kitsune06 · 03-15-2007, 12:01 PM

oh, but the Saint is so hot...

**Batbike** · 03-16-2007, 06:13 AM

Originally Posted by ridebikeme

Ummmm... my suggestion is also to stop crosschaining... or perhaps even change to a compact crank.

You didn't mention whether your bike is a double or triple, however the Saint hub would be quite a bit of work for a shop to set up. The long cage derailleurs are setup for cassettes that are 27 tooth and up.. is yours in that range?

You mentioned that your derailleur hanger keeps bending ... have you replaced it each time that has happened? You can generally bend these back, but obviously they are not as strong as they once were...

Good luck with this!!

To address above important points:

YES! I need to stop crosschaining -- however, VERY surprised that a 53-21 or 53-23 combo would cause this problem (thought it would happen only at extreme level of 53-26). I don't crosschain at extreme level, but at the other gears. I have been working on dropping to lower 39-15 or 39-16 to compensate. I have a traditional double 53/39 crank with a 13-26 cassette. I may eventually change to compact 50/34 and 12-25 cassette. I would not use the Saint hub.

As for derailleur hanger bending, yes, I have had LBS realign it -- which I guess is bending it back. I am thinking about getting a speciality/welding shop to weld me a new hanger made of stronger material such as steel or ti. Not sure if this can be done, but I think it could be ...

Bottom-line, thinking the problem is with the derailleur hanger, so that is what needs to be strenghtened. After that it would be a gear combo issue and the need for a compact crank. Any one have thoughts on my thoughts?

**KnottedYet** · 03-17-2007, 02:57 PM

Mechanical engineering question:

Is the hanger on a carbon fiber bike made made of aluminum so that the aluminum will fail rather than sending the stress into the delicate carbon fiber?

Sort of a 'sacrifice the hanger to save the frame" situation?

My cheap-o aluminum frame bike has a steel hanger. (magnet sticks to it, so I assume it's steel)

**ridebikeme** · 03-17-2007, 04:20 PM

Very wise thoughts on replacing the hanger... you definitely have to be concerned with the material of the frame vs the hanger. If the hanger is stronger than the material of the frame, you could potentially damage the frame... which is a much bigger expense. I would generally NOT think about bending the hanger back unless I didn't have a choice ...if I had to order one or needed to get myself back home. Even though your LBS can bend it back very accurrately, it still is NOt the same strnegth that it once was. The other issue could be that the bike may have some sort of chain line problem... other than the obvious of cross chaining... you might have them check that as well.

The idea of the compact crank will definitely give you lower gearing, and might just fill that need!

Good luck!!

**Batbike** · 03-19-2007, 05:49 AM

Originally Posted by KnottedYet

Mechanical engineering question:

Is the hanger on a carbon fiber bike made made of aluminum so that the aluminum will fail rather than sending the stress into the delicate carbon fiber?

Sort of a 'sacrifice the hanger to save the frame" situation?

My cheap-o aluminum frame bike has a steel hanger. (magnet sticks to it, so I assume it's steel)

I believe that is true ... instead of having to replace the entire frame, you end-up saving frame and replacing hanger.

**Batbike** · 03-19-2007, 05:52 AM

Originally Posted by ridebikeme

Very wise thoughts on replacing the hanger... you definitely have to be concerned with the material of the frame vs the hanger. If the hanger is stronger than the material of the frame, you could potentially damage the frame... which is a much bigger expense. I would generally NOT think about bending the hanger back unless I didn't have a choice ...if I had to order one or needed to get myself back home. Even though your LBS can bend it back very accurrately, it still is NOt the same strnegth that it once was. The other issue could be that the bike may have some sort of chain line problem... other than the obvious of cross chaining... you might have them check that as well.

The idea of the compact crank will definitely give you lower gearing, and might just fill that need!

Good luck!!

Two questions based on above:

1. Are you saying it is NOT a good idea to get a new hanger in a stronger material because it would be too heavy?
2. What sort of "chain line problem" ... I don't understand what this could mean?

Thanks!

**ridebikeme** · 03-20-2007, 07:39 AM

To answer your questions.... first chainline can be determined by putting the chain on your small chainring and the middle cog on your rear cassette. At that point, it should be in a perfect straight line, if you were standing behond the bike looking at it. If there is any deviation, then I would recommend you taking it to your LBS and have them look at it.. sometimes you can make it a bit better.

Secondly, by having a derailleur hanger stronger than ithe orginal will definitely put more stress on the frame.. exactly where you don't want it. I would also recomend NOT straightening it out .. when that happens the integrity of the aluminium is compromised by bending and then again when we s straighten it.

Have you put more thought into the compact crank?

**Batbike** · 03-20-2007, 01:19 PM

Originally Posted by ridebikeme

To answer your questions.... first chainline can be determined by putting the chain on your small chainring and the middle cog on your rear cassette. At that point, it should be in a perfect straight line, if you were standing behond the bike looking at it. If there is any deviation, then I would recommend you taking it to your LBS and have them look at it.. sometimes you can make it a bit better.

Secondly, by having a derailleur hanger stronger than ithe orginal will definitely put more stress on the frame.. exactly where you don't want it. I would also recomend NOT straightening it out .. when that happens the integrity of the aluminium is compromised by bending and then again when we s straighten it.

Have you put more thought into the compact crank?

first, to answer your question about the compact crank -- if changing the derailleur hanger is a bad idea, then that would be my next plan of action.

now, a quetion for you ... if the chainline is "off", what would cause that and how would the LBS fix it?

Thanks!

**ridebikeme** · 03-20-2007, 01:36 PM

Let me see if I can answer your questions...

First, as I mentioned earlier, if you are indeed bending your hangers, you should replace them and NOT straighten them. Obviously there is some sort of problem, so taking it to your LBS is something that I would definitely recommend. Perhaps changing your crank would give you the gearing that would be more beneficial for you and your bike... but it's still something that should be checked just in case.

Secondly, if your chain line is off there are a few options. It can be off because the frame itself is off(and happens more than one would believe). It can also be something very minor... perhaps a spacer behind your cassette.But regardless of what the problem is, it sounds like this is something that should be investigated. You obviously have a nice bike, and it's worth the extra time to figure out what the problem might be.

Good luck!!

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