Broken cassette cog!?

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alpinestar
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by alpinestar

So Yesterday I was out on a short but fast ride. Near my house I stopped at a red light, and when starting... crunch sound, and I was on the deck. Bit surprised as to what had happened. I saw the chain lodged between 2 cogs and thought that the cassette had just come loose. At home I notice a cog missing, and went back to where it had happened and found the cog in several pieces! Cassette has done 800km with a fresh record chain! The cassette is a 12-27 chorus. I have been in contact with Mantle where I bought it and reported it to their service department.
Pisses me off that my campag levers got scratched Image
Anyone seen this before?
Image


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Sin2000
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by Sin2000

Yeah - I had this happen to a 14 tooth sprocket once after a couple of 000 miles on the cassette. Replaced under warranty. Most of the sprocket remained in situ - only 2 or 3 teeth missing so I rode on aware only that there was a very strange noise in the 14 sprocket.

I believe the most common cause is damaged freehub splines, but could of course be a faulty sprocket. I would check your freehub.

I should add that I have been riding Campag groupsets for 20 years and have done about 100,000 miles in that time - so it’s unusual.

by Weenie


alpinestar
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by alpinestar

Good to hear it was replaced under warranty! hoping for the same! It was a bit tricky getting the casette back on after, like it was binding in a few places, but with a bit of back/forth with the large cogs, it came free again. But will probably order a new body, just to be safe!

tarmackev
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by tarmackev

Impossible, its Campag. Campag never never breaks.

XCProMD
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by XCProMD

Looks like a fatigue crack. There is no yield and that material has a pretty ample plastic field apart from at least 30J at - 20 degrees C Charpy V toughness last time we tested it.

Was the lockring tight? Is the body worn/dented?

joeyb1000
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by joeyb1000

Was this on a campagnolo hub?


https://www.velonews.com/2014/08/bikes- ... ion_342663

The break point in the article look identical to yours.

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Calnago
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by Calnago

I have never actually seen a cog break like that, but I have learned something from this thread, so it’s a good morning. I was thinking along the same lines as XCProMD with the tight lockring etc, as I just assumed the OP is using a Campy freehub. And maybe he is, in which case I’d be baffled and probably spend way too much time trying to figure out the actual cause. And of course there is only one way you can install the cogs on a campy hub, and the splines are thick and beefy. But the article that Joey linked to was informative in that I have come across freehubs like that where it was possible to install the cogs incorrectly. I knew what I was doing and installed them correctly but the thought did cross my mind as to just how easy it would be for someone to install them incorrectly at this point. What I didn’t realize was the possible consequences of incorrect installation so this is good to know should I be dealing with any such hub in the future.
I’m a better mechanic now than I was five minutes ago because of something I read on WW. Yay!
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Butcher
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by Butcher

That sure does look the same. Bicycles are a pretty simple machine and it's always interesting how people cans screw up something so simple. I only thought it was possible to install the cassette one way. I look/align the timing mark and the cassette slides right in.

mattr
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by mattr

I've had a couple of (cheap) shimano pattern splined hubs which when combined with the loose, stamped sprockets, it's possible to get them on (with finger pressure) in the wrong orientation.

Pretty obvious tho, as they aren't concentric!

Sin2000
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by Sin2000

My issue (some years ago on an 11 speed set up) was on a Campag hub (Fulcrum to be precise). The hub splines were too soft I think and were scored, making it difficult to slide sprockets on and off easily. I think that was the most likely cause of my problem but I can’t be sure

alpinestar
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by alpinestar

joeyb1000 wrote:
Mon Jul 15, 2019 3:07 pm
000
Very interesting article! This is on a novatec hub for campag. I have had this wheel set for 4 years, this is my 3rd casette on it. I have set the casette to the shop where I bought it, so cant check if its possible to mount them in several posistions. Defenetly something to be aware of, if that is possible! I seems to remember that there is only one way to mount them, but will check once I get a new casette.

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Calnago
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by Calnago

Definitely pay super close attention to how the splines are engaging with the cogs, even if there is only one way to mount them, and if you can see any gaps between one or more of the four cog tabs and the relevant spline, well then that could very well be the root cause. It’s unfortunate this happened to you, but it’s something I’ll certainly look at closely if I come across any non-Campy hub install in the future. I’d find it interesting if you’d be so kind as to follow up in this thread with what you find out along these lines. Because now they we know it wasn’t a Campy hub, it would be good to know if there is less than ideal engagement with the Novatec hub.
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bikeboy1tr
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by bikeboy1tr

Whenever I install Campy Cass. I always look for the stepped splined portion of the freewheel and then find the matching stepped portion of the cog to align the two together. For some reason ever since the first one I ever did this is how I always installed the cogs no matter what manufacturer of freewheel.
I guess thats just the way I see it.
I have installed the Shimano cog (one) flipped over and it went right on np. Took the bike out for a test run and the chain was jumping over the tooth profile on that particular cog and at first I thought the chain was toast but after I realized it was working fine with the rest of the cogs on that cass. headed home and reversed the cog back to the proper position. Now when I do the Shimano cogs I look for the stamped number side of the cog and make sure it is facing out.
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alpinestar
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by alpinestar

Ok first step is done, Mantle replaced the cassette, so a new one is one the way. I am in Spain for the moment so won’t be able to check if it’s possible to mount it wrong for another few weeks.


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bm0p700f
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by bm0p700f

I think the novatec body is just like the ones zone. Wrote about. I am always careful when installing the cadette to get the the stepped alone in the right place. If a warranty is granted it should be taken as goodwill. Personally I think the op should check how he I stalled the cassette and suck it up if installed incorrectly. Blaming the cassette for an installation error caused by a weight saving freehub design is a bit of a stretch.

by Weenie


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