Campagnolo Super Record EPS 12s Chain Slap Issue

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Supergooch
Posts: 11
Joined: Sat Feb 06, 2021 1:09 am

by Supergooch

Hi All,
I have purchased a new road bike with Campy SR12s WTO 60 wheels. Running a front 53/39 and rear 29/11.
What I have noticed when racing or riding at pace. When im at a high cadence and stop abruptly peadling, the chain will slap on the top of the chain stay giving me the feeling the chain has dropped .
This will happen in either small or large front Chainring and in the smallest 5 rear cassette rings.

I have returned the bike to the retailer and taken it to a specilazed campy shop both cannot pick any faults of issues with set up or equipment as its brand new.
We also simulated the issue with a diffrenent wheel set Bora one 35mm disk and got the same problem.

Can anyone shed some light on this please . Its very annoying . I don't get this problem on any of my other 4 road bikes all with Campy Group sets and wheels all 11speed.

maxim809
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by maxim809

Hi, welcome to WW Supergooch. Moving this over to the Road forum. Hopefully someone can answer your question there.

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Hexsense
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by Hexsense

sound like sticky freehub body or insufficient RD cage tension.

When you stop pedaling, the cassette still have some momentum to rotate forward. Usually, this is all eaten up by the RD cage tension.

However, if the force from your wheel also contribute into this forward rotation of the cassette (sticky freehub), then the cassette will keep rotating a bit more, creating chain slack on top of chainstay. Then once it stop, RD cage pull back the chain removing the chain slack.

please put your bike on a stand and then try to spin rear wheel very fast and release your hand from the bike. If rear wheel spinning can induce crank to keep rotating at a good speed, you have sticky freehub.

Otherwise, check if you size the chain too long so that RD cage doesn't give sufficient tension to stop chain slap. Especially if you use oversized pulley cage. Those can significantly reduce chain tension by a lot.

Supergooch
Posts: 11
Joined: Sat Feb 06, 2021 1:09 am

by Supergooch

Hi Hexsense , tried rear wheel spin test and no stickiness or movement of the crank at all.
Reluctant to shorten chain as its within the Campagnolo specifications.
On close observation it's as if the cassette keeps rolling forward with the inertia of the spin and then gets pulled back by the RD.

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micky
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by micky

Sounds like "super sticky" freehub with perhaps too much grease in it.

Valbrona
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by Valbrona

Could also be the jockey wheels. You will not know how freely they spin until the chain is removed. Grease can dry out if bike is stored in a warm environent, especially if it is of the non-petroleum type.

Chain could be too long.

Supergooch
Posts: 11
Joined: Sat Feb 06, 2021 1:09 am

by Supergooch

As indicated prior had a Campag approved workshop investigate could not find anything wrong with set up or equipment . And all equipment is new.
Could this be normal behaviour for new 12s groupset and new WTO wheels ?
The workshop did send a request to HQ of Campag in Italy but I doubt Ill get anything menaingfull back.

Hexsense
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by Hexsense

Supergooch wrote:
Tue Feb 09, 2021 5:28 am
Hi Hexsense , tried rear wheel spin test and no stickiness or movement of the crank at all.
Reluctant to shorten chain as its within the Campagnolo specifications.
On close observation it's as if the cassette keeps rolling forward with the inertia of the spin and then gets pulled back by the RD.
hmm. Interesting.
Normally, if it's sticky freehub, the freehub spinning would induce the crank to spin as well. But that maybe not the case if the crank also has high resistance to spin.
Anyway, cassette (on freehub body) keep rolling forward with the inertia of the wheel spin is a big telling that something is not right there in that area.
Again, this can be either because of very weak RD cage tension, or sticky freehub. A very well working freehub will not rotate much with the wheel inertia. It usually overshoot just a bit when you suddenly stop the crank pedal from high cadence. But not to the level you describe. And not doing it repeatedly with just force from wheel inertia. Maybe somehow cassette bind the freehub body? Since you have many other bikes, those should show some good example of how it should work.

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micky
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by micky

Borrow a pair of wheels from any friend/shop and see if it works dirrently.

I find this kind of problems when I get bikes which have been stored for ages without any use.

Supergooch
Posts: 11
Joined: Sat Feb 06, 2021 1:09 am

by Supergooch

Hi All , So after alerting this issue to the distributor whom I purchased the bike and Groupset from. They contacted HQ Campagnolo in Italy and sent a video simulating the issue.
The response from HQ Campag was due to the extra weight of the Cassette 32/11 and 29/11 that at high speed it has iniertia to keep rolling forward and is a limitation of the product.
Suprised I have no heard other users of this product complain about the same issue if its as Campy indicates a known limitation (problem) of this product. Very dissapointed and considering returning the groupset for another brand.

Butcher
Shop Owner
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by Butcher

I'm glad you have an answer but it's not the answer you probably wanted to hear.

If you are the one in a million that has a problem, then it's hard to make a total redesign. Maybe a aftermarket cassette. Omni Racer has one out. I cannot see myself in a situation slimilar to yours.

maxim809
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by maxim809

Very interesting find, and thank you for sharing.

I'd be curious to know the length of your chainstay, as well as the number of links on your chain (probably 110 if your chainstay is within the supported range).

While WTO60's and 53/39, 11-29T may be a "popular" combo for those who choose SR12spd, I can see the complaints for this being harder to amplify and thus not as much user chatter because Campy is the less common of the big 3, let alone EPSv4.

I'll keep an eye out for this strictly out of curiosity. I imagine I'd be able to recreate it using your steps assuming the limitation is chainstay+chainlink agnostic. I also wonder if this is EPS-specific, or if it impacts mech 12spd as well. Either way, thanks for reporting back.

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MrCurrieinahurry
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by MrCurrieinahurry

Supergooch wrote:Hi All , So after alerting this issue to the distributor whom I purchased the bike and Groupset from. They contacted HQ Campagnolo in Italy and sent a video simulating the issue.
The response from HQ Campag was due to the extra weight of the Cassette 32/11 and 29/11 that at high speed it has iniertia to keep rolling forward and is a limitation of the product.
Suprised I have no heard other users of this product complain about the same issue if its as Campy indicates a known limitation (problem) of this product. Very dissapointed and considering returning the groupset for another brand.
Can we see the video please
Formerly known as Curryinahurry

Bobbyc123
Posts: 290
Joined: Mon Oct 19, 2020 10:40 am

by Bobbyc123

I've actually experienced the same thing on all my campy bikes. 11s mechanical and eps as well as 12s mechanical. Never knew what the issue was but never thought it was a big enough issue to explore further. I'd never heard someone else experiencing the same. Good to know!

Supergooch
Posts: 11
Joined: Sat Feb 06, 2021 1:09 am

by Supergooch



Video Simulating the issue and Chainstay length is 405mm

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