AMoney

I'm not going to change the names. We're talking about bikes, not children! I took two pictures of the derailleur hanger on the bike:



My bike is the Giant TCR Advanced Pro. I'm running the Wheels Manufacturing 290 derailleur. Right now, the bike is shifting very well. Here's a link to the derailleur hanger: https://wheelsmfg.com/derailleur-hanger-290.html

The bike I had significant issues with the derailleur hanger was a Cannonade CAADX. It had significant issues even when I used the Wheels Manufacturing hanger, which was a 199. Here's a link: https://wheelsmfg.com/derailleur-hanger-199.html

FBinNY 

I respectfully disagree with those who bring up "weak" hangers.

First of all, I remind you that these are designed to break to protect the frame, in the same way a fuse protects a circuit. And I agree that some are weaker than others and may break too easily, analogous to a 15amp fuse in a circuit that could handle 20amps.

But bending is a different story. No hanger, regardless of its lack of strength bends without provocation. Normal shifting simply doesn't produce enough force. Also more force is needed to downshift, and that would bend the hanger out, rather than in.

So, I come back to my earlier suggestion that the OP needs to explore how and why he keeps bending hangers before doing anything elsre.

Kontact 

Except the replacement hangers don't shear off, they bend. They are generally all made of un-heat treated aluminum and can be bent a fair amount more than once before they will actually crack.

Kontact 

Those both look reasonably stout. It is interesting that the one you had the most problems with is mounted on the outside of the dropout. Inside is a more typical design as it allows the hanger to bend away from the dropout after a side impact to the derailleur.

But that doesn't explain why you've had so many problems.

Koyote

Your problem is almost certainly user error -- which means that a new bike won't solve it.

Crankycrank

I'm looking at the photos and could just be a distorted image but it looks like the left dropout is tweaked quite a bit which could cause some problems. Just asking.

Kimmo

Haven't read the thread, just replying to the OP -

Rim brake Di2 is a great way to minimise your maintenance. For extra points, a frame with a threaded BB. But if your frame has a sketchy hanger (some are just soft), it'll keep messing up your shifting. Another advantage of Di2 is that you can adjust it on the fly...

There's a good chance the Wheels Manufacturing replacement for your hanger is stiffer; I'd try that.

Kontact 

Why does it look like you are missing the rear hanger mounting screw?

phughes

Yes, it looks to be missing, and looking through the hole, it looks as if the holes do not line up as a result, so the hanger has turned on the existing screw. The missing screw would certainly explain the necessity of frequent adjustments, since the hangar would move.

AMoney

The bolt wasn't in as far in as the other one, but it wasn't missing. I took a picture from the other side. It's hard to see in the photo, but the one on the left sits further out, so it didn't go as far in:


Nevertheless, I was able to tighten it somewhat, see the before and after.




It seemed very tight (about as the tight as the one that goes further in) I don't want to tighten it any further at the moment. I tried to find the torque recommendations but didn't have any luck. Are torque specs specific to each derailleur hanger? Or, do they apply to derailleur hangers in general?

choddo

Is it just me or does there seem to be a lot of paint missing from around your dropout?

Kontact 

It is a little strange that the forward screw is more countersunk than the rear. It could be that the edge of the rear screw is hanging up on the edge of the hole instead of allowing the head to settle in. So I'd take that bolt out and look at whether the hole is actually shallower than the rear. If it isn't, you might have some wiggle that would explain why this hanger isn't behaving.

These don't have to be torqued. Probably 3nM is way more than enough. This is more a "just past snug" situation, and shouldn't require a torque wrench at all. If they get loose, that's where you would use low strength. loctite to prevent moving.

AMoney

When I took the pictures this morning, I was wondering if the left dropout was bent. After your post, I took a better picture of it. If it is in fact bent, I imagine it would be at least partially responsible for some of my shifting problems, but how specifically? Also, how easy would it be to unbend the dropout?

Crankycrank

Dropouts need to be parallel and there is a special tool to make it easy but you can improvise or just take it to a shop. If the dropouts are bent and non-parallel it can put stress and even slightly bow the axle in some situations making an unstable drivetrain sometimes. I say "sometimes" as it's usually a minute difference but with 10+ speed setups that can make a big enough difference as they have to be very precise.

AMoney

I took off the derailleur hanger, took a picture of the right dropout, and put the derailleur hanger back on. It was the same as before. The bolt was going all the way through. I think that that the front hole is countersunk.

Kimmo

You know what would be nice?

If Wheels Mfg would make direct mount versions of their hangers for more recent bikes... The double hanger with two mounting bolts situation is just awful.

Probably not part of the problem here, since it's so widespread and isn't known for causing these dramas, but it certainly wouldn't help.

Anyway, I'd look closely at how the hanger connects to the dropout, as FB suggested. From your pics, I can't see any reason why one bolt should sit further out; maybe start there.

FBinNY 

Bend or break there has to be some outside force involved. Which is the point I've been trying to get across since way back in post #12. In post #35 I posited that----

Instead, I suspect that the hanger is not secure and rigid where it's attached. All too often, the mating surfaces either aren't flat, or something is preventing the hanger from pocketing correctly. That allows for it to move slightly throwing the RD off.

It's nice to see that folks are FINALLY considering this. Hopefully the OP can get the hanger properly and rigidly secured to the frame.

Kontact 

I believe I made the same point in my first post in this thread. But the OPs Giant hanger does seem secure, and the Cannondale is not available.

There are definitely some hangers which bend surprisingly easily, and some people that seem blissfully unaware of how much they bang their bikes into things. So far their is no one cause for the OP's problems - mainly because we have no way of testing the previous bike.

FBinNY 

Agreed that.some hangers are mire flexy than others, but bending wants an explanation. Also agree that some people are unaware of their n rough handling, so that MAY be the explanation.

But the OP has reported multiple bent hangers on this bike, which is much more than a fluke.

IMO blaming the hanger is a distraction keeping people from a serious search for the actual cause.

Kontact 

If the hanger wasn't bent, then straightening it wouldn't have corrected the problem (at least temporarily).

@AMoney, do you have your QRs nice and tight? I have run into a lot of people who's quick release I could open with my fingers. Hangers like on your bikes rely on the QR for structural strength.

FBinNY 

Never said there wasn't either bending or other movement/deflection. That's a given. However the question remains whether it's movement or bending, and in either case HOW and WHY that's happening.

AMoney

I have repeatedly checked the rear QR since this thread. It is about as tight as it can be while still allowing it to be fully locked.

When you say pocketing, what do you mean? IF the dropout on the left side is bent (which is hard to tell if it is, I'll get another set of eyes or two in real life), would this be a possible culprit? If so, how easy would it be to unbend the dropout (which is carbon)?

choddo

Not very but that doesn’t look like carbon under the missing paint. Metal dropouts bonded to carbon stays perhaps? How did that paint get damaged so much?

FBinNY 

The left dropout may or may not be bent, but that's not the problem here. (In any case, CF assemblies cannot be bent. Any movement beyond yield fractures the matrix and compromises the structure)

Your issue is all about the hanger and right dropout.

By pocketing properly, I mean fitting together perfectly flat, with no wiggle room. The bolts should be holding it in place, but only that.

Test by assembling the hanger onto the frame holding it in place with thumb and forefinger. It should feel rock solid and unable to wiggle.

If this seems to be the issue, I'd assemble it with a bit of autobody filler, bolt it together tight squeezing excess out, and letting it cure. Then finish by mounting the wheel and using a hanger tool to align.

grumpus

I'm wondering if that raised screw head under the skewer nut is affecting the axle clamping force in some way that is causing problems with the hanger.