SRAM Red Etap Front Derailleur Adjustment

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CHL
Posts: 18
Joined: Sat Aug 09, 2008 11:20 pm

by CHL

Hello All:

I installed SRAM Etap on my 2015 Super Six Evo HM. Took a lot of adjustment to the spindle and adding shims behind the crankset (Hollowgram SL with 109mm spindle) to obtain sufficient clearance between the crank arm and front derailleur (yeah with a stock 2.5mm spacer, the crank arm hits the front derailleur). Any case, I can't dial in the shifting of the front derailleur. Up shifting without load executes cleanly. Shifting with any load is less than ideal with the chain refusing to upshift at times.

Adjusted the derailleur to exact specification and played with the height of the derailleur to what SRAM recommends. Still not as clean as my old 10 Speed Mechanical SRAM and vastly inferior to DA7800 that I had a long time ago. I am using SRAM Red Yaw chainrings (53/39) paired with a Cannondale Hollowgram SL crankset. I am using a Shimano DA9000 chain.

Would anyone have any tips on properly adjusting the derailleur?

Thanks,
C

sungod
Posts: 1702
Joined: Fri Dec 24, 2010 9:37 pm

by sungod

getting the front/rear guide marks on the cage exactly aligned is important, the height does not seem so critical, i mounted slightly higher than the guide mark and also set the high limit to put the cage slightly further out from the chainring

shifting on mine is fine, old srm/sram red cranks with praxis works rings and red 22 chain, not had any failed shifts

is the fd mount to the seatpost flexing? the clamp on mine is really chunky, i didn't need to use one of the supplied wedges, the motor in the fd probably applies much more force than manual fd, if the mount is flexing it will throw off the shifting

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WhyZ
Posts: 15
Joined: Wed Feb 15, 2017 2:08 pm

by WhyZ

Hi C,

Did you fixed your problem??
I have same problem on my bike(storck fascenario 0.7 with campagnolo speed 11 crankset).
My case, front derailleur between crankarm clearance is 0.1~0.2. So I afraid the hitting FD when I pedallig.
If you solved problem, please let me know.
Thanks in advance.

RichTheRoadie
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Posts: 2070
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Location: Sydney, Aus.

by RichTheRoadie

eTap won't shift from the inner ring to the big ring under power uphill. It's a built-in protection thing.

Next time you're out, try the shift uphill, then try it again when it flattens out...

Clingon
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Joined: Thu Oct 13, 2016 2:54 am

by Clingon

^ Is this really so? I have not heard it elsewhere. How does the groupset 'know' that power is being applied?
I have yet to try eTap for myself, but if true this sounds like a serious problem.

RichTheRoadie
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by RichTheRoadie

Clingon wrote:^ Is this really so? I have not heard it elsewhere. How does the groupset 'know' that power is being applied?

It doesn't know power is being applied, but it does know you're going uphill and trying to execute a big ring shift when you probably shouldn't be.

Clingon wrote:if true this sounds like a serious problem.

No - it's a clever method of preventing you from wrecking your drivetrain.

Clingon
Posts: 25
Joined: Thu Oct 13, 2016 2:54 am

by Clingon

RichTheRoadie wrote:it does know you're going uphill

So there is an inclinometer?

RichTheRoadie
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Location: Sydney, Aus.

by RichTheRoadie

I would guess an accelerometer.

Clingon
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Joined: Thu Oct 13, 2016 2:54 am

by Clingon

Thanks, makes more sense now. It does indeed sound like a clever feature.

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sugarkane
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by sugarkane

its got an accelerometer.. so the guess is it can tell when your going up hill
I've had the same issue and with customers.. going up hill and shifting the big ring up just won't work.. as soon as you get on a pretty much flat road or down hill shifts up like normal.. thing is.. why would you do it.. my customer has a bad habit that we are trying to stamp out..

Clingon
Posts: 25
Joined: Thu Oct 13, 2016 2:54 am

by Clingon

sugarkane wrote:why would you do it.. my customer has a bad habit that we are trying to stamp out..

Too true. It was Rich's "under power" that had me a little concerned.

I took a peek at the FCC tear downs of the FD to see if I could spot the accelerometer. Unfortunately the images are not of sufficient quality to read all the chip numbers, but I have circled what I think may be the chip in question.
Image

If anyone else is curious to see the internals of the eTap group, the relevant links are:
Right Shifter
Left Shifter
Front Derailleur
Rear Derailleur

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Calnago
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by Calnago

I'm not a SRAM guy but I like to at least understand how all the various systems work. This is the first I've heard of this. I've often thought that the force by which both Di2 and EPS shift the front cannot be good for the system in scenarios such as this. With mechanical and a little "shift management" it is easy to deal with basically any shifting situation thrown at you. In this case you could go "hard" for a couple seconds then ease up for a second as you make the awkward shift comfortably using the right amount of physical force necessary, light or heavy. Done, no stress on the system. But with EPS and Di2 there is no "finessing" of the shift possible, they will force that chain onto the big ring when you punch the button with the same intense force each time with no regard for how painful it might be to your system. Of course, you can still do exactly the same thing I just described... go hard for a couple seconds, then simultaneously ease off for a second and make the shift, which is less stressful on the components but the force to throw that chain around is non negotiable.
If eTap had an inclinometer, it would theoretically never allow you to shift from small to big ring when going up hill. So an accelerometer would make more sense and "probably/might" work if you applied the same technique in riding that I just described, a natural thing one might do if riding any mechanical system uphill. I just don't understand how it knows exactly when the conditions have been met that would either allow you to shift, or prevent you from shifting. Either way, I don't like any system that limits conditions that I could shift in otherwise simply by applying a little finesse and knowledge of how to get to the gear you want under any circumstance. This is where mechanical shifting systems and a little experience can, imo, always outshine the electrical systems. At least so far. But I would like to know more about how this seemingly unpublicized feature/drawback of eTap handles this situation. Because the way it's being described here so far doesn't sound so hot to me.
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Clingon
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by Clingon

Calnago wrote:I've often thought that the force by which both Di2 and EPS shift the front cannot be good for the system in scenarios such as this.

I have had this same thought, although both Di2 and EPS have been around a good while and I have yet to hear of such shifting resulting in an issue; indeed the ability to complete what I consider to be inappropriate and awkward shifts is often espoused to be a benefit of electronic systems. Which makes it all the more curious as to why Sram felt the need to prevent such shifts, without even considering why Sram and every review I have read has failed to mention it.

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Calnago
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by Calnago

Agreed. I think the issue is one of increased wear and tear, on the chain and the derailleur itself. I find it hard to imagine any electric front derailleur being useable 20 years from now whereas I could easily see the current batch of mechanical front derailleurs being perfectly fine if properly maintained.
And since this thread is the first time I at least have ever heard of this I'm not even sure at this point it's just not that eTap's front derailleur and/or chainrings is simply not as efficient as either Di2 or EPS.
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jlok
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by jlok

SRAM obviously implemented "Three Laws of Robotics"...
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