KMC X12 Chain on Campagnolo 12 speed 50 34

Discuss light weight issues concerning road bikes & parts.
mag
Posts: 436
Joined: Thu Mar 16, 2017 12:23 pm

by mag

At least Campy UT-CN300, Rohloff Revolver 3, Abbey Decade and also Park Tool CN-4.3 work with 12s.
Most current Pedro's tools are usable as well, see their compatibility table: https://pedros.com/wp-content/uploads/C ... 24x613.jpg
This is one from the usually cheaper ones, but no price yet as it's a new model: https://uniortools.com/eng/product/1647 ... ool#946257
And there are definitely others that I missed.

graeme_f_k
Shop Owner / Manufacturer
Posts: 396
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Location: UK
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by graeme_f_k

kdviner70 wrote:
Mon Apr 15, 2019 3:35 am
graeme_f_k wrote:
Mon Apr 15, 2019 3:21 am
kdviner70 wrote:
Sat Apr 13, 2019 7:11 pm
wilwil wrote:
Sat Apr 13, 2019 3:48 pm


I have just bought these missing links and notice it doesn't say Campagnolo on the packet but does on their website. There isnt a specific Campag version. I bought them to carry for emergencies because as Calnago said, theres no reason to use them with 12 speed. I have heard and I really dont know if its true that the Campag 12 speed chain is noisy and some people are using the new Sram 12 speed chains.

Ive used KMC links on Campag 11 speed with out problems but I dont reuse them like some do. KMC chains were never an improvement over Campag with 11 speed.
Let us know if they do fit. That will prove I did something wrong.
The dimension figures quoted neglect tolerances.

Campagnolo don't reveal their maxima / minima for any component dimension - so KMC are just guessing in their manufacture - if you had a Campag chain near the max of it's over-link-plate tolerance and a KMC joining link at the minimum of their pin length / joint step tolerance, it's entirely possible that you might find it difficult or impossiblle to close. 0.05mm doesn't sound like a lot in terms of pin length difference but it's still the difference between a light interference fit and a clearance fit ... as a material example, the difference required to secure an old-school headset into a frame is only 0,075 - 0.1mm and they are tight enough to need a press to insert ...

If it did close, it could fail. I have about 20 joining links of various formats I have collected over the years with various failure modes. When customers ask me why I only ever recommend them as an emergency get-you-home, I just pour out my little container of failed links.

A properly rivetted chain is exceedingly unlikely to fail but it does have to be done correctly - it's not about being in the 21st century or otherwise - it's just good engineering and correct tool use.

Please remember, if you fit a third party chain or a joining link and you suffer a failure of any sort in the transmission, Campagnolo are not bound to honour any element of the warranty on your shiny new groupset, any more than Shimano or SRAM are if you mix and match their components ... your chances of needing to avail yourself of that warrnty are very, very small, admittedly - but users do need to be made aware of that fact.
I think I under stand what you are saying. So when the Campy website states that the new 12 speed chain is 5.15 mm is that an average?
Up to a point, yes, it "can be" an average but it's more complicated than that.

This is really basic engineering.

In a production situation (as distinct from making extremely high precisionone-offs, where accuracy is limited by the inherent accuracy of the tooling), a level of inaccuracy has to be tolerated because of issues such as tool wear, human error and so on - also, consider effects such as heating and cooling is some parts subject to high friction or to significant heat transfer.

So, where a nominal dimension is given, there will be an associated set of maxima and minima. The overall width doesn't necessarily have to be an average, though - a sizing could be, say, 10mm +0.05 / - 0.00mm for instance - so a system in this case would tolerate an oversize of 0.05mm but wouldn't tolerate an undersize.

Even commonplace things that we all take for granted, such as threads or cartridge bearings have tolerances attached, generally (but not always) governed by regularly applied standards (ISO, JIS, BA, SAE etc). Sometimes (threads are a good example) there are a range of standards that might be applied, according to the manufacturing requirement, including cost - so, all threads need to have a degree of movement in fit - the smaller that movement is, the less liable to "backlash" the thread is - but the harder the parts will be to mate and the higher the cost of maintaining that standard of fit. The question is then, how much (for example) backlash is tolerable in the system?

Most manufacturers will publish some data - and some data can be derived if enough accurate measurements are taken of enough production parts - but it is extremely rare for manufacturers to make proprietary dimensins including tolerances public. On the rare occasions that I have needed full schematics from Campagnolo or any of the other manufacturers we work with, including tolerance data, the information has fallen under the non-disclosure agreements that we have signed.

This is part of the reason that third-party "compatible" parts will always void warranty.

There are two unknowns at work - the third party in virtually every case will either only have derived data to work from (or may be relying on stolen IP ... yes, industrial espionage is alive and thriving in every industry) and they may vary their manufacturing with no reference to the company with whose parts they are seeking compatibility and in the same way, the company making the parts that the third party has supposed compatibility with, may vary some aspect of their manufacture in a way that renders a "compatible" part not compatible.

This is very relevant in the context of chain tooling (discussed elsewhere in this thread) - it's noted that third party makers are "silent" on the subject of 12s compatibility in their 11s chain tools, where Campagnolo made clear from day one that UT-CN200 (the 10s tool) can't be used with 11s chains (and vice versa) but UT-CN300 is compatible with 11 and 12s. They've done the dimensioning and tolerance work and designed it that way from a position of knowledge.

In 12s, even more than 11s, the pin has to be driven in an extremely straight line (very little lack of concentricity can be tolerated) and the fit has to controlled to extremely tight tolerances. Other chain tools may and may not hold the chain accurately enough, may and may not drive the rivet concentrically enough - but from personal experience and looking at chains with failed joins, we have found that the risks of failure are far higher with third-party tools and - important note - worn or damaged "correct" tools.
A Tech-Reps work is never done ...
Head Tech, Campagnolo main UK ASC

by Weenie


graeme_f_k
Shop Owner / Manufacturer
Posts: 396
Joined: Mon May 26, 2008 12:21 pm
Location: UK
Contact:

by graeme_f_k

DaveS wrote:
Sun Dec 01, 2019 10:20 pm
The sram eagle 12 quick link works great. It fits better than the KMC.
How many data points is that assertion based on?
A Tech-Reps work is never done ...
Head Tech, Campagnolo main UK ASC

DaveS
Posts: 2715
Joined: Fri Mar 24, 2006 1:26 pm

by DaveS

graeme_f_k wrote:
Thu Jan 02, 2020 1:07 pm
DaveS wrote:
Sun Dec 01, 2019 10:20 pm
The sram eagle 12 quick link works great. It fits better than the KMC.
How many data points is that assertion based on?
It's based on the fact that the side clearance between the inner and outer plates is very close to the same as all other links on the chain. The fit of a KMC 12 link is sloppy and an AXS link too tight. It's the best choice until campy starts making a quick link.

I started working in a machine shop in 1971 and worked as a machining process engineer at a nuclear weapons plant from 1981-2003. I know how and what to measure.

carbonazza
Posts: 39
Joined: Wed Apr 10, 2019 9:14 am

by carbonazza

DaveS wrote:
Thu Jan 02, 2020 4:21 pm
It's the best choice until campy starts making a quick link.
Thanks to a previous DaveS comment. Going the Campagnolo way is the only advice I skipped from Graeme when building my EPS 12s bike.

Because I like waxing my chains, had spare Eagle quick links around, didn't have the required chain tool and wanted to ride it immediately !

After 1000+km, no regrets, the shifting is flawless, and the quick links looks indeed to fit well. Not tight, not loose.

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