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Alcanbrad 08-02-20 08:27 AM

Etap Red ghost shifting - HELP!
So I got a tricky one. I recently upgraded the drivetrain on our 2014 Co-Motion Carrera tandem to Etap Red and we are experiencing ghost shifting under high pedal loads (Low cadence climbing scenarios). First the setup:

Compact crank 34-50 chain rings 34-50 - New
Cassette SRAM cassette 1130 11-42 11 speed - New
Chain SRAM Red-22 (made up from 2 chains to achieve length) - New
Jockey cage Digirit aftermarket 49T capacity - New (
Wheel is 40 spoke with Whites Industry Hub. No discernible evidence of freehub bearing wear. (i.e can't wiggle cassette at all)

Shifting is flawless, what every rider with shifting woes dreams of. When this occurs, we are introducing some heavy loading to the system: Bike + riders > 400lbs, 2 people applying pedal force together.

When we experience the ghost shift, it doesn't shift a complete gear, I believe a chain plate is riding on top of a tooth, then snapping loudly back into track. Doesn't feel good and scares the cr*p out out us when it happens (I am also fearful of snapping the chain given our weight and power).

I observe that while the jockey wheels are lined up perfectly with largest cog, however, don't appear to be in the same plane as the cassette cogs. I purchased a Park derailleur hanger adjustment tool, and the hanger was a bit off, however, once adjusted did not solve the problem.

We have experienced the issue in the 2nd, 5th, and 11th cogs and I am sure we would in all of them.

B-screw is adjusted with a little over 6mm clearance between jockey wheel and largest cog.

I have adjusted the B-screw for larger clearance and don't know if we still had the issue, however, shifting performance was very poor. I have also adjusted the derailleur in a bit to center the chain link over the cog in resting state and found same: I.e. don't know if that fixed it, but shifting performance very poor.

We have not experienced the issue with the stock jockey cage, however, the capacity is too low for such a system and not an ideal solution.

The setup is sold to many tandemists so this is not a one-off implementation, though, granted it is not a common high volume one either and I realize the parameters I am operating at here are outside the original design spec of the derailleur.

So I believe that I am experiencing issues caused by frame flex and the question is: What can I do about it? Is there a better cassette? Better chain? Would adjusting the derailleur hanger to bring the plane of the jockey wheels closer to the plane of cassette cogs help? (a new frame is not in the scope of possibilities)

Looking for the collective experience of the forum to help us out here.

Thanks in advance.

fietsbob 08-02-20 11:32 AM

No experience with that specific one ..

I have found all the tooth redesigns that are the fast shifting hyperglide ... used almost universally now
tend to catch the chain and it shifts on you too easily when you wish it were to stay put ...
shift points dead center .. the pulley aligned under under the cog consistently.. you say they are..

Maybe new chain and cassette ? 2 X the power may wear things quicker..

Blind guesses will continue..

put it up on a repair stand and try some of the things you mentioned..


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