Campagnolo EPS, it works for 10 speed cassette. But why.....

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Birdman
Posts: 283
Joined: Mon Aug 17, 2015 4:03 pm
Location: Chicago, IL, USA

by Birdman

Seems like both Di2 and eTap only requires the fine adjustment set up on ONE sprocket. However, EPS requires the fine adjustment set up (a.k.a. Zero Setting) to be done on TWO sprockets, 2nd smallest and 2nd largest.

Does this mean: EPS relies on the two-sprocket Zero Setting set up system to define the sprocket to sprocket spacing?

If yes, does this mean: I can trick EPS, and set it up for a 10 speed cassette? Achieve this by doing the Zero Setting on the 2nd smallest sprocket and 1st largest sprocket? Or even a 9 speed cassette.

The answer... YES. I just tried it, and yes, it worked for 10 speed Ultegra 6700 cassette. It shifted well. However, since the limiting screw is limiting the travel to the largest cog, it isn't that seamless since it WILL try to go to the 11th cog thinking it is still there.

But why... With that 10 speed trial completed, that means Campagnolo's EPS system does not have pre-define sprocket to sprocket spacing, instead, Campagnolo allows the mechanic to define that themselves. That seems weird to me. Sprocket to sprocket spacing doesn't sound like something that people should mess with. Does anyone know why Campy does it this way?


Image

Referencing the instructions below, which I gathered from PDF manuals or official Youtube videos.

Campagnolo EPS rear derailleur set up
1. Shift to largest rear sprocket, or 2nd largest.
2. Hold both "mode" buttons for 6 seconds until blue LED turns on.
3. Shift to 2nd smallest sprocket. Center derailleur on sprocket.
4. Press right "mode" button to save the sprocket position.
5. Shift to 2nd largest sprocket. Center derailleur on sprocket.
6. Press right "mode" button to save the sprocket position.
7. Set limit screw.

Shimano Di2 rear derailleur set up
1. Shift rear derailleur to the 5th largest sprocket
1. Press button on front junction box
2. Fine tune derailleur position with rear shifter shift paddles
3. Press button on front junction box
4. Set limit screws.

SRAM eTap rear derailleur set up
1. Shift rear derailleur to the largest sprocket.
2. Fine tune derailleur position with left and right shift buttons or derailleur buttons.
3. Set limit screws.
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graeme_f_k
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by graeme_f_k

Its more complicated than that.

The system has quite deep resilience to being abused like this (and it is abuse - it's not designed or consumer-tested to be used in this way) because in applications on the teams, they sometimes need to be able to do things that Campagnolo would never recommend that an end-user should do, be it for testing or for some other purpose ...

In loose terms, the two-sprocket set up actually applies a compensation algorithm to a lookup table. In the case of fooling the system with a 10s system, the system will still look for the 11th sprocket because it's still in the lookup table. Only the limit screw will prevent the RD from seeking the 11th sprocket.

The problem then is that the RD "thinks" it's there, so will try to move to it if commanded to do so. Restrained by the limiting screw, the motor can, if this happens repeatedly, end up damaged. So don't do it, unless you want to pay for a new motor - needless to say, this would not be an issue covered by warranty.

You'll also find that the indexing is close, not perfect - and rear shifts under load are sometimes not correctly completed. The reason is that the "stretched" lookup table does not correctly interpret the spacing from 2nd to bottom to second to top as far as the top 3 sprockets (which in 11s have differential spacing according to the size of the starting sprocket) are concerned and the proportionality of the shift intervals is not perfectly matched to 10s, it's perfectly matched, unsurprisingly, to 11s ...
A Tech-Reps work is never done ...
Head Tech, Campagnolo main UK ASC
Pls contact via velotechcycling"at"aim"dot"com, not PM, for a quicker answer. Thanks!

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Calnago
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by Calnago

Graeme, great info, as always. You touch on a point that I've often wondered about, not in relation to the rear derailleur however, but the front...

graeme_f_k wrote:...The problem then is that the RD "thinks" it's there, so will try to move to it if commanded to do so. Restrained by the limiting screw, the motor can, if this happens repeatedly, end up damaged. So don't do it, unless you want to pay for a new motor - needless to say, this would not be an issue covered by warranty.

So, here's my question.... The force that the electric powered front derailleur exerts is substantial. What happens in the case where perhaps someone inadvertently tries to shift from small to big chainring in a completely inappropriate situation, like if they start a hill climb completely crosschained (small chainring, smallest cog) and then, looking for an easier gear, erroneously presses the button to shift from the small chainring to the big. Now I know no one on this forum would ever do such a thing, but in the case of some beginner just trying to figure things out (or just a simple brain fart or accidental button touch by someone who knows better), does the derailleur go ahead and try to muscle that chain onto the big ring regardless of whether there's a cadence of about 10rpm and a lot of force being applied to the pedals, or does it somehow recognize that a "force limit" has been reached, it's not a good time to shift, and back off. Seems to me that shifting under these kinds of conditions would cause a lot of undue stress and premature wear (possibly even break it) on the front derailleur motor in the same way as if the rear derailleur was hitting up against a limit screw when it thinks there's another cog to reach.

Thanks,
Cal
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mike
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by mike

if you bought eps, you should use 11 speed cassette. otherwise, look for older di2 10 speed only. the cost of spending EPS is already great, so i would spend the extra money and convert to 11 speed cassette.

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