Campagnolo RD SR-002M Cage on Record EPS RD

Discuss light weight issues concerning road bikes & parts.
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naavt
Posts: 33
Joined: Sun Nov 25, 2018 6:58 pm

by naavt

Hi,

I'm trying to put an 11-29 cassette to wotk with my EPS RD. As it stands, all spockets work but the derailleur doens't shift from the 11 to the 12 sprocket with the lose H screw (to accomodate the 29 sprocket). I have to shift from the 11 to the 13 and back to 12.

I'm one tooth above Campagnolo specs, using 50-34 and 11-29 makes 34. Campagnolo states a maximum of 33 (which I also find odd since the mechanical ones accept a 34 difference).

I've seen a thread here at WW where someone installed a Potenza cage to an EPS RD to accomodate a larger cassette, so basically I have 3 questions:

1st - Can I install the SR mid cage to my 2016 Record EPS RD, and is Is it a direct fit?

2nd - Since the mid cage will accept a larger number of teeth, I'll assume that it will be no issues whatsoever in using my combo 50-34 + 11-29 and that all shifting will be spot on right?

3rd - If cage lenght only affects the number of teeth one can use, how come the Potenza cage/Record EPS combo mod that I've seen accepts a 32 sprocket? :shock:

Thanks

by Weenie


joeyb1000
Posts: 223
Joined: Thu Mar 03, 2016 8:37 pm

by joeyb1000

Can't answer your questions, but I've used an 11-29 with a 52/36 on EPS with no problem at all on two different bikes. I didn't touch the H screw. I regularly check my drop-out allignment.

naavt
Posts: 33
Joined: Sun Nov 25, 2018 6:58 pm

by naavt

joeyb1000 wrote:
Wed Aug 07, 2019 3:15 pm
Can't answer your questions, but I've used an 11-29 with a 52/36 on EPS with no problem at all on two different bikes. I didn't touch the H screw. I regularly check my drop-out allignment.
I'll say that's probably because the chainstay lenght of those two bikes allowed that. I'll assume that's not the chainrings since the tooth difference is the same as mine 50/34.

graeme_f_k
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by graeme_f_k

naavt wrote:
Wed Aug 07, 2019 12:14 pm
Hi,

I'm trying to put an 11-29 cassette to wotk with my EPS RD. As it stands, all spockets work but the derailleur doens't shift from the 11 to the 12 sprocket with the lose H screw (to accomodate the 29 sprocket). I have to shift from the 11 to the 13 and back to 12.

I'm one tooth above Campagnolo specs, using 50-34 and 11-29 makes 34. Campagnolo states a maximum of 33 (which I also find odd since the mechanical ones accept a 34 difference).

I've seen a thread here at WW where someone installed a Potenza cage to an EPS RD to accomodate a larger cassette, so basically I have 3 questions:

1st - Can I install the SR mid cage to my 2016 Record EPS RD, and is Is it a direct fit?

2nd - Since the mid cage will accept a larger number of teeth, I'll assume that it will be no issues whatsoever in using my combo 50-34 + 11-29 and that all shifting will be spot on right?

3rd - If cage lenght only affects the number of teeth one can use, how come the Potenza cage/Record EPS combo mod that I've seen accepts a 32 sprocket? :shock:

Thanks
This has been covered repeatedly in other posts by myself and others.

Admittedly, you might have to pull a few threads together from those posts but here it is, as succinctly as I can put it.

11-29 is specced only on 2015 and later mechanical RDs, as these use Embrace to keep the top jockey closer to the casette than the earlier 11s systems (2009-2014) on which the RD geo for EPS is based.

In early 11s system and in EPS, if the H-screw is correctly set for a 29, the chain is not controlled well enough at the 11T sprocket so you will hit the problem that you have - in a brand new system with a very careful and slightly out of spec set-up you can make 11-29 work but it's not spot on and occasional "over-throw" of the chain and jamming between the smallest sprocket and the frame can occur. This has all been extensively tested on the teams and we don't make a habit of it, even in those circumstances where we have a high level of control over frame geo, set-up and wear and tear rates ... which of course we don't in public land - so the short answer is, it doesn't work predictably and with the standard set-up, which is why it's outside of the advised spec.

The issue is nothing to do with chain wrap. Just adding a longer cage to a RD does not of itself increase it's sprocket size range, unless the placement of the upper jockey relative to the jockey pivot also changes - and that then becomes a very complex matter. Fundamentally, though, the tracking angle of the RD stays the same so the jockey to sprocket clearance for any given position of the H or B screw stays the same. All putting a longer cage on does, unless the design is fundamentally different to the short cage, is increase the amount of chain wrap so allowing a larger chainring size differential. Hence if you look at the technical manuals online, you can see that the max sprocket size of, say, the Athena 11s double system (short cage) and triple system (medium cage) is the same and that the sprocket size ranges for each RD don't change. Likewise Veloce 10s. The extended cage is about being able to run a triple with a 23 tooth max front difference alongside a 12-29 at the rear, not about being able to run a wider cassette.

On the additional downside of fitting the longer cage to an EPS RD (and this was also extensively trialled on the teams and in other field R and D, including at Velotech), when fully extended on big-to-big, the amount of leverage exerted over the top pivot asembly by the extended length of the cage (an extra 20% more-or-less), causes unwelcome side-effects in the wear and tear in the upper pivot assembly and stresses the composite of the upper pivot moulding closer to it's ultimate failure point. Additionally, the extra leverage also causes issues in accuracy of shifting because the body of the RD lacks the overall rigidity to accommodate it. In a new RD this is not a massive problem but in a more worn unit with some slop in he pivots etc, it contributes to poor shifting / lack of correct chain control.

Some rear hangers are long enough that the H screw will allow adjustment for a 32 biggest sprocket even with a short cage - the long cage then is for chain wrap- but the problems of accuracy of shifting, over-stressing of the upper pivot, lack of rigidity and less-than perfect shifting all still apply.

Hence also the reason why we don't advise the fitting of the medium cage to a non-HO mechanical RD to increase it's capacity - it looks like it "should" work but there are problems that were engineered out in the revisions of the HO series.

I've said it several times before and I'll say it again - the specs err on the cautious side and they err on the side of what is physically tested not just in one set of circumstances, with one frame design, one hanger design and a set of peculiarities in set-up as an individual final user might have - the specs are designed to work across all the frame and hanger geos that are encompassed within the technical manual, with one set of relatively simple set-up parameters. They also take into account wear and tear, small errors in set up, imperfections in chainline and hanger alignment and manufacturing tolerances, all of which affect exact function.

Finally, the specs assume a level of function - what applied torque will a shift occur at, for instance, what is the time lag from the mech moving to the chain starting to engage, partially engage and fully engage with the sprockets / chainrings, how secure is tht engagement, what are the probabilities of over-ride of the extremities on the cassette and what failure modes are risked and how high is that risk?

If you start to mess with the specs on the basis that your mate says it works on his bike ... you are binning all of that R and D for which you have indirectly paid ... and you might end up breaking something. Including yourself - or worse, from my point of view, me, if I happen to be riding behind you when you come to grief.

It's also maybe worth asking this question. Given the level of market demand for EPS to be able to handle a 32 or even a 34 sprocket over the last few years, if the solution was as easy as just adding a medium cage, why would Campag not have just done that? It would have been an easy win over the competition (I know Shimano did it but had to revise the RD in the process) ... the answer is contained in the above. That's part of the reason, at least, why 12v EPS uses totally re-designed components all the way through.
A Tech-Reps work is never done ...
Head Tech, Campagnolo main UK ASC

naavt
Posts: 33
Joined: Sun Nov 25, 2018 6:58 pm

by naavt

Thank you for your detailed explanation graeme_f_k.

I have some questions about some of the info that you wrote if you don't mind.

When you state
graeme_f_k wrote:
Fri Aug 09, 2019 6:24 am
The issue is nothing to do with chain wrap. Just adding a longer cage to a RD does not of itself increase it's sprocket size range, unless the placement of the upper jockey relative to the jockey pivot also changes...
Does this means that the placement of the upper jockey is different on the medium cages?

Bear in mind that I'm asking this (and planned to do the cage swap), after reading a post where some guys installed a Potenza cage on a 2015 EPS RD and allowed a much larger cassette to be used.

Take note that I didn’t go for a "hack" like a Potenza cage and trying to do the right thing I assumed that the SR cage fitted my Record RD since they share almost all tech specs. One thing is new for me tough, and that the part where you mention my EPS RD is based on a pre 2015 design and thus not allowing the 34 tooth difference.

I understand all you say about the stress load on non HO RDs fitted with a medium cage, and you mention the big/big combination, so crosschained. If that was the only concern, a simple software upgrade in the Campy app allowing the user to set up and deny certain chainring/sprocket combinations would do the trick.

There's even an aftermarket and ridiculously priced oversized jockey wheels cage to do the trick in Campy RDs.

On a side note (and no harms intended), I also understand when you state:
graeme_f_k wrote:
Fri Aug 09, 2019 6:24 am
if the solution was as easy as just adding a medium cage, why would Campag not have just done that?”
I’m a long Campy user. I love the heritage and the looks of it. For that I’m willing to pay a hefty premium price tag that – in reality – excluding those and making a straightforward comparison to, say, a RED eTap system, I can’t see why Campy insists in making their stuff in a “closed circuit” (dedicated tools for everything comes to mind).

What I'm trying to say is that every manufacturer has its own agenda. I love Campy bits but they do a life for themselves selling their stuff (which is right), and everything that reverses that logic by supporting mods that fulfill costumers needs without buying an entirely new system is going against sales quotas!

Anyway, bottom line. I really do preserve my health and well-being (and I have a child to care), so if you are telling me that there’s an eminent risk of failure to put this to wotk, I can still cancel the cage order I’ve just made yesterday.

And just to be clear, you think that there’s no way to put my 11-29 cassette to work on this setup, or have you any suggestion that will do the trick without the associated risk?

Thanks
Last edited by naavt on Fri Aug 09, 2019 2:03 pm, edited 1 time in total.

naavt
Posts: 33
Joined: Sun Nov 25, 2018 6:58 pm

by naavt

So here I am resurrecting this topic just to inform anyone interested that I’ve made the swap from the short EPS RD cage to the medium SR cage.

Have installed a new chain since the older one was too short for this new setup and zero set the RD.

Things look good by now but I’ve just made a few meters around my front door to make sure everything was working properly.

It now shifts from the 1st to the 2nd small cog without issues, which it didn’t with the short cage (remember that I have 1 tooth more than the specified Campag spec – 34 instead of 33).

Tomorrow I’ll make a recovery ride and this next weekend I have a 200 kms hard pace with 2700+ elevation group ride, so I’ll post my findings after that one.

Image

Boshk
Posts: 426
Joined: Wed Jul 19, 2017 2:59 am

by Boshk

Well that throws a little spanner in the build plan.
Never knew that eps 11 spd doesn't technically work with 11-29 and 50/34 but they produce all the equivalent cranks and R/SR cassettes.

I was going to switch to Record EPS upgrade kit if my Chorus mechanical 11/29 and 50/34 didn't shift well on integrated bar/stem combo.
Last edited by Boshk on Sat Oct 19, 2019 3:15 am, edited 1 time in total.

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corky
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by corky

Campy sometimes makes it difficult to love as an end user

naavt
Posts: 33
Joined: Sun Nov 25, 2018 6:58 pm

by naavt

Boshk wrote:Well that throws a little spanner in the build plan.
Never knew that eps 11 spd doesn't technically work with 11-29 and 50/34 but the produce all the equivalent cranks and R/SR cassettes.

I was going to switch to Record EPS upgrade kit if my Chorus mechanical 11/29 and 50/34 didn't shift well on integrated bar/stem combo.

Things are working flawlessly with the medium SR cage.

50/34 11-29 with plenty of clearence for the biggest sprocket.

Every change is perfect. I’ve made a change from the first time I’ve assembled the cage though. I’ve fitted the return spring on the hole that gives it the most tension.

Gear changes became snapier this way, comprared to when I first assembled the return spring on the moddle hole.


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by Weenie


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