Campagnolo Rear Derailleur Issue

[Calnago]

So after all that it was the hanger alignment after all? Aargh!
Especially when you open with "Aside from hanger alignment what could cause..." Kind of implies you've checked the hanger alignment and it was good. Oh well, thanks for reporting back and glad you got it resolved.
UNLESS... They bent the hanger to match a problematic bend in your derailleur. Hope not.

[timmbo]

Well, I'd hope not too. Unfortunately, I don't have an alignment checker so can't check their work (and relied on the LBS first time around) - they're a very reputable shop, so I'd assume they know what they're doing!

[Calnago]

I came awfully close to doing exactly that (bending the hanger to match the derailleur) even though I knew it would be putting the hanger "out of alignment" in the horizontal plane. I even had a couple spare hangers on hand just in case It broke while adjusting. In the end I never resorted to that, but it certainly crossed my mind. If you get a chance it might be good to have it checked again somewhere to make sure the hanger is aligned as it should be and not aligned to match a faulty derailleur. I would just ask them to check it at this point but NOT to adjust it if it's off, especially if it's working fine now. However if you do find that it's been thrown out of alignment to compensate for the derailleur, that is not a good solution in the long term.

[timmbo]

I came awfully close to doing exactly that (bending the hanger to match the derailleur) even though I knew it would be putting the hanger "out of alignment" in the horizontal plane. I even had a couple spare hangers on hand just in case It broke while adjusting. In the end I never resorted to that, but it certainly crossed my mind. If you get a chance it might be good to have it checked again somewhere to make sure the hanger is aligned as it should be and not aligned to match a faulty derailleur. I would just ask them to check it at this point but NOT to adjust it if it's off, especially if it's working fine now. However if you do find that it's been thrown out of alignment to compensate for the derailleur, that is not a good solution in the long term.

...I finally got hold of a Park Tools DAG2.2 - the hanger is straight!

Slightly off-topic, but how is one meant to remove the RD? I've just been putting a T25 key in and turning it counterclockwise - this is exceptionally difficult, and it doesn't come off easily. It eventually came free, but there was a bizarre smell of burning rubber/plastic (!) when it came undone. There seems to be a hex bolt on the reverse side of the mounting bolt (inside of the hanger), but none of my hex keys fit it!

[davidw]

Any body figure a resolution to this? I have the same exact symptoms as the OP. Small ring and 4 smallest cogs the chain derails to the inside of the lower pulley wheel and, albeit subtly, on the big ring smallest cog there's skipping at the pulley wheel. It's been stated that the twist in the cage is intentional but it seems awfully drastic on my RD. When looking from the rear of the bike, the back of the cage points diagonally to the spokes as if the pulley wheel is facing outward of where the chain enters. Frustrating for sure, but mostly discouraging considering the cost of such components.

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[Calnago]

Davidw... your post is very timely. And you are one of the very few whose issue seems to be what I started this thread about. I am currently testing a few things and I have a theory. Here's what I've found out. To fix my problem (over a year ago now), which could be reproduced on two bikes which were both working flawlessly and the derailleur hanger was perfectly aligned, all I had to do was to replace the cage. I replaced it with a Chorus cage and it was fine. But was the original cage really at fault? I do not know, yet, as my theory is that it may be due to nothing more than an assembly error at the factory. But I'll know if that's correct soon enough. Last year, when I removed the "problem" cage, I placed the cage on a perfectly flat surface along with another cage that I knew was good on the same surface and I just could not tell if one was in fact different than the other. They appeared to be the same. I still have the cage that did not seem to work.

So fast forward to now. I'm currently doing a build and am going to test this out at the expense of a new Record chain. I have just installed a brand new Super Record derailleur onto a Colnago C60. Prior to installing it I made sure the hanger was perfectly aligned along every axis... vertical, horizontal, and in between... went round the whole wheel and it is bang on.

Next I installed the chain at the correct length, on small/small. In this case it is a 11/36 combo. You don't need to attach cables to see if this problem exists. It is apparent immediately. Closed up the chain and gave it some good turns. If the problem exists then the chain will derail from the lower pulley (or want to), on the inside. If it runs smoothly, it's good. Pretty simple test. I even made sure the high limit screw was adjusted so as to not give the situation any "help" in keeping the chain running smoothly on the lower pulley.

Ok... just finished that part of the test. All good. Chain runs perfectly in small/small with no indication that it wants to jump. Here's the video...

https://vimeo.com/186350367

Ok... so now I'm going to remove that derailleur, remove the existing cage and replace it with the cage that did not seem to work from last year. If it runs perfectly, then I am going to assume the problem lies in the initial assembly and will bet that if you simply disassemble and reassemble the cage onto your derailleur the problem will be solved. If, when I do this swap, the problem that I experienced last year is present, then I can be sure it is the cage and will send the cage to Graeme in the UK at Velotech as I trust he will examine it, maybe try it out to reproduce the problem, and make sure the issue gets brought up with Campagnolo. Stay tuned.

[davidw]

Interesting. I'll stay tuned for more info. It seems to me that there may have just been a goofed batch that got sent out because of how few people this has affected. Even my mechanic made note of how twisted up the cage looked on my bike. Thanks for the info and for putting this stuff to the test!

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[Calnago]

The trouble is when anyone says something like "that cage is twisted", then a lot of folks with a shifting issue tend to jump and down and say "My cage must be twisted too". When in fact a slight "twist" is totally normal. Like I said, I've had the issue on two derailleurs, one was sent back to Campagnolo, the other I took upon examining myself. And when removed and taken apart, I really couldn't ascertain a definitive difference between any of the parts of the good one versus the one that seemed to be causing the problem. The only way I could tell something was wrong was to install it and run the chain like I did in that short video. It would actually derail off the inside like I tried to show in some of the still photos at the beginning of this thread. So now I'm finally getting around to testing that cage that on a known good derailleur. Out of curiosity, could you pm me to let me know where you purchased the derailleur from. Thanks.

[davidw]

Pm sent.

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[Calnago]

Ok, I just replaced the cage shown working perfectly in the video above with a cage I replaced last year which was not working at all. Keep in mind that last year I simply replaced the cage/pulley assembly and all was good. So the problem had to lie in either 1) the cage/pulley assembly itself or 2) an improper assembly at the factory.
Well, i just did my little test with the "old cage" on this brand new derailleur and it works perfectly. My only conclusion is it must have been an assembly error. Here's the video I just took with the cage I removed from a unit giving me problems last year, but installed on this brand new derailleur...
https://vimeo.com/186490496
So, @davidw, my recommendation to you is to completely remove and disassemble the cage and pulleys, taking care to make sure the lower pulley is oriented in the right direction (arrows on the pulley), and reassemble the entire thing. If you're not comfortable doing that then take it so someone who is. I suspect this will solve your problem. Also, take extra special care to see what may be amiss in the initial assembly. That was impossible for me to do since when I took it apart I wasn't even thinking about looking for something wrong in the assembly phase. Good luck.
As far as I'm concerned, at this point the issue I was describing in this thread is resolved and closed.


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[Nefarious86]

Could it have been something as silly as a back to front lower pulley wheel? For me it would be satisfying that the problem is fixed but also rather annoying not knowing the root cause haha.

[Calnago]

Yes, me too. That's the whole reason I went through this exercise... to figure out the underlying problem. But I really did check the directional arrows on the lower pulley before pulling it apart. Pulling it apart was my last resort to see if a new cage would work. And it did, so I left it at that but kept the "faulty" cage till now so I could reassemble it on a good derailleur and see if the problem occurred, in which case it would have clearly been a cage/pulley issue. But it worked fine on the new derailleur so my only other explanation is somehow it got a bit cockeyed at the factory.


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[Calnago]

Yikes! I think I spoke too soon above. I am still doing a bit of testing with that cage which I thought was maybe faulty, then later attributed it to an assembly error. But doing some further testing I was able to reproduce the issue again, so at this point I'm putting the original cage back on, and if it works... I'll be sending the cage that doesn't seem to work back to Campy for closer inspection.

[davidw]

I left my bike with my local mechanic. He's been talking with Campy about the issue. They want to make sure all the measurements are up to spec and if they are, then they're gonna take the derailleur back and try and get the issue solved.

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[bm0p700f]

I had a bike in the shop with a skipping chain, using chorus parts, over the jockey wheels. Changed the jockey wheels, aligned the hanger, set the gears up more than once. After a a while scratching my head i changed the front ring and bingo issue resolved. The old ring did not look that worn but it was holding onto the chain then releading it causing the skip.

The moral of the story assume nothing.