Impressive disaster for my Campy SR12sp EPS RD

Discuss light weight issues concerning road bikes & parts.
groover08
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Joined: Sat Feb 10, 2018 7:10 pm

by groover08

Calnago wrote:
Tue Jun 11, 2019 9:54 pm
The derailleur hanger didn’t break?
It did not. It was bent after the incident but it did not break. I know what you mean about the soft regular pinging. I had this once before on a DA Di2 bike and was able to catch it early and adjust the limit screw accordingly. That’s why this incident on the Campy SR was so odd - there was literally no warning. It had been perfect for two weeks, and for the 84 km immediately prior to the incident. Anyway, the shop has claimed a full warranty replacement from Campy USA and sent the derailleur back to them. We’ll see what Campy says.

by Weenie


Nefarious86
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by Nefarious86

I'd be wanting the frame inspected too after that.

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Calnago
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by Calnago

Well, just because it didn’t happen in the first two weeks, it’s still fairly new. With EPS, you fine tune things “before” you set the limit screw, as there is a bit of overrun in the electronics that you don’t want the limit screw interfering with while adjusting. Once it’s dialed, then you set the limit screw. It can be an easy thing to forget to do at the end, and If I were a betting man, I’d bet this is what happened. Whoopsie! If the hanger is bent, I’d get it replaced while you’re at it.
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ParisCarbon
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by ParisCarbon

Thats a strange one... how close were the spokes to the backplate of the RD jockey wheels.. I know from experience some Mavic wheels the spokes would literally brush the back of the RD and needed to be adjusted accordingly... any slight wheel flex at the wrong moment? Also any debris on the road, sounds dumb but did you pick up a twig or something.. Ive nuked a RD on CX bike from a woodchip, but the entire hangar snapped as well...
Hopefully you get thing sorted!

groover08
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by groover08

:welcome:
ParisCarbon wrote:
Tue Jun 11, 2019 10:33 pm
Thats a strange one... how close were the spokes to the backplate of the RD jockey wheels.. I know from experience some Mavic wheels the spokes would literally brush the back of the RD and needed to be adjusted accordingly... any slight wheel flex at the wrong moment? Also any debris on the road, sounds dumb but did you pick up a twig or something.. Ive nuked a RD on CX bike from a woodchip, but the entire hangar snapped as well...
Hopefully you get thing sorted!

That may be shaping into a cohesive story. I rode 2 miles on a rough back road about an hour before the incident. It was close to a gravel road, but more like a disused concrete farm road. Perhaps that knocked the RD out of alignment suffiiciently for it to explode the way it did. Anyway, I will update the thread when I hear back from the shop and Campy USA.

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Calnago
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by Calnago

Riding on a rough road should definitely not knock the derailleur out of alignment. Those hangers are not made of cheese.
Last edited by Calnago on Wed Jun 12, 2019 2:10 am, edited 1 time in total.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

Marin
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by Marin

You'd probably have to have 3 things happen at once: Power stroke - slightly looser"pushing" spoke near the derailleur - slight bump in the road. This will give you the extra 0.5mm that makes the spoke catch on the cage -> BANG.

Your rear wheel is also laced so that the pulling spokes will push the crossing towards the derailleur under power. I try to cross the other way.

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Calnago
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by Calnago

One thing you can compare when you get the bike back, hopefully all set up correctly and the limit screw set, is to compare the adjustment of the limit screw. Luckily you have a pic of it, not great, but probably good enough to be able to tell if the original adjustment was correct or not. Here’s a blowup of your limit screw, lots of blue threadlokcker. You can see that if it is turned in at all, it’s certainly not very much. You can barely see the protruding silver of the screw against the stop. So, once you get your fixed bike back, hopefully perfectly adjusted, then you can compare the two screws. If it’s obvious the screw is turned in much farther than it is shown here (hardly at all), then there’s your forensic conclusion as to what went wrong, and pretty good proof as to who is responsible.
Image
Just make sure the screw isn’t turned in too far, which would mess with the electronics as it tries to shift but runs into the stop prematurely.
Last edited by Calnago on Wed Jun 12, 2019 3:59 pm, edited 2 times in total.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

groover08
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by groover08

That’s superb advice, I highly appreciate that. In a way, how the shop responds to this will be a good guide to my future interaction with them. I will report back once this sorry episode is over.

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WinterRider
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by WinterRider

Found a high limit screw on one new RD w poor fit... loose enough to move while riding. After adjustment I de-greased and applied thread locker.. both sides.
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Calnago
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by Calnago

I always apply a little low strength Loctite (purple) to the limit screws on Campy mechanical on the front derailleur (the rear generally has quite a bit of blue Loctite on them, as shown in the pic above). But the front screws also have a very fine thread and while some years ago they used to come with preaaplied Loctite, they don’t anymore, so just a small amount to set things generally means I never have to touch it later on. It’s just good build practice.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

groover08
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Joined: Sat Feb 10, 2018 7:10 pm

by groover08

This photo of the new RD was taken today upon the bike’s return to me. The limit screw in this new RD is clearly screwed in quite a bit further than it was in the RD that disintegrated (photo above). So I think it shows what might have happened here. Thank you all for your input.
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B885E6D0-1C7B-487E-B547-2663B569AEF2.jpeg
New RD, detail.

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Alexbn921
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by Alexbn921

Improper adjustment and wheel flex with get you sometimes. I sold a set of zipp wheels to a big guy and he didn't setup his limits for the new wheel. First climb he stood up in the biggest cog and bam. Destroy wheel and derailleur.

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