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A Bit Flummoxed By My Campy Chorus 12spd RD
I've never had any issues adjusting an RD before, but I have to admit that my Chorus 12 speed RD has presented a bit of challenge. I can't quite get low gears to shift right while keeping excess noise down. Everything is groovy on the higher end, in fact the top 8 gears sound found and shift fine. The lowest 4 though....not so much. The RD' top pulley certainly looks like it's positioned well.
For reference I'm running an 11-34 cassette with a 50-34 crank. My chain stays are 405mm long center-to-center. Would fiddling with the RD positioning screw again be a possible solution? I think my upper pulley is pretty close to the 11T cog (where I setup the RD position). I don't get any real noise at the end of the cassette. |
#2
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Another small 'gotcha' is ensuring the wee brass washers that the der housing(Cut VERY clean and long enough..si?) pushes against are there and flat. Another thought..internal der inner wire routing?
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Chisholm's Custom Wheels Qui Si Parla Campagnolo |
#3
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RD hanger alignment is the first thing I do with any bike, even a new one.
Campy now has specific chain length requirements for each pair of chain rings and various ranges of chain stay length. Yours should be 55 inches. When I had chorus 12, I probably didn't pay enough attention to the screw that adjusts the clearance between the upper jockey pulley and largest sprocket. Obviously, there can't be any contact in any gear combination. I had some issues with the 11-12 shift that may have been due to cable friction with my frame's internal cable routing. https://www.campagnolo.com/US/en/Sup...al_drivetrains |
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Thanks, all.
The RD hanger is newish, and I checked it for flatness. The bike is a Look 595. I do wonder if the RD hanger is not stiff enough? I don't know what forces or moments the Chorus 12 speed RD exerts on the RD hanger compared to the Record 10 speed RD that used to be there. I wish I could source a Steel or Ti RD hanger to see if that makes a difference. The cables seem to run freely. The 595 does have some internal routing, but it doesn't doesn't really force any tight bends, especially between the right brighter and the RD. Cables are exterior before entering the down tube just aft of the head tube on either side. As for flatness, I made double sure to cut my cable housings and dress them so that the cuts were perpendicular to the housing axis and not, uhm, manky. I am 98% sure that I cut the chain the right length. Is it measure twice and cut once or measure once and cut twice............... I did make sure that I cut the chain the right length as one of the first things I noticed when I did the install was that Campy had a new chain length spec. Maybe I can convince the wife that flying me and the bike to Vincenza is justified...... I'll bet the folks at Campy HQ could sort things out. I love everything else about this group: ergos, shift feel...... This RD issues is driving me a bit batty, though. I'm almost to the point of investing in Tune's laser RD alignment tool. Last edited by PsiSquared; 04-21-2021 at 04:42 PM. |
#5
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Flatness is not what you needed to check. A hanger alignment tool is needed to be sure the hanger is parallel to the rear wheel. See the park tool website. Get the shifts to larger sprockets working first, then evaluate the shifts to smaller sprockets. If those hesitate, cable friction could be a problem.
Last edited by Dave; 04-21-2021 at 06:06 PM. |
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#7
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From the sounds of things - if you haven't already aligned it and it sounds like you haven't aligned it - I'd bet considerable amounts that its the hanger. A Park DAG tool or similar is your friend here.
All my bikes have alloy hangers and I've bent them back with the appropriate tool. If its scary just take it to a shop and they'll have it sorted in a few minutes. But if you're wrenching your own bikes you should have a DAG and be comfortable using it. |
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Replaceable hanger:
https://wheelsmfg.com/derailleur-han...anger-134.html Also, ensure that the RD “joint”, which attaches to hanger, engages the tooth on the hanger. Easy to miss this. |
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I had the same issue with 12 spd Record on m other bike which I just took to a bike shop and they got it right away. I'm an okay mechanic on most bike components but derailleurs always give me a hassle. |
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#12
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It is funny but with Campy even if you just have the cable into the exit of the RD a little off (meaning not straight) it will cause symptoms like your having Which is basically a cable friction prob I also had a similar prob & thought it might be hanger alignment which it wasn't |
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It is also possible to anchor the cable at the wrong place. The "washer" that has 2 legs and a slot for the cable can be turned to the wrong position under the 5mm cable anchor bolt. I did this due to my poor vision and poor lighting conditions. It was OK across 7 or 8 gears and then the error added up to too much for the last 4-5 gears. This caused the wrong amount of derailleur travel for each shift.
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#14
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I believe I somehow did the same & had the same problem |
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Thanks, all.
The DAG-3 revealed the RD hanger needed some tweaking. Some tweaking was done, and gaps are down to less than 2mm at the worst, which means that the RD is aligned to within less than 0.4° all the way around. The RD is much happier now. I should have bought derailleur hanger alignment tool a long time ago. |
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