Rear derailleur problems
 

I have Cube Curve Pro 2015 model and just had my Shimano Acera Rear derailleur changed to the shadow type but the gears did not work properly.
I took the bike to one of my LBS and they couldn't fix my problem until they tired Shimano Altus rear derailleur so I know have the bike with that derailleur.
Anyone here might know why my bike did not work with the Acera derailleur ?

Indexed gear systems rely on the shifter pulling "X" amount of cable, and a matching derailleur moving "X" amount to match.
There are different generations, for different years, and number of gears.
It's possible that your shifters pull "X" amount of cable per shift, but the other derailleur was designed for "Y" cable pull.

IIRC, Shadow and non-Shadow derailleurs have different pull ratios.

The guy at the LBS who worked on my bike tried a lot of different tigger shifters as well as the same rear derailleur shadow acera, regular acera and the only combo that worked was downgrading to altus. He had no clue why Acera did not work and I have a new Acera trigger shifters. All the other derailleurs and triggers had a problem that the gears only shifted up the cassette or down the cassette.

Having good shifting up the cassette but not down, or the opposite, are often from things like bent hangers or friction prone cable routing. If the shifting in the well working direction was good with each shift, so that the 1 to 2 shift was as well indexed as the 6 to 7 shift then the cable pull ratio of the der is correct for the rest of the system.

BTW there are 9 speed Shadow ders that share the same cable pull ratio as the previous non Shadow 9 speed ders. However the amount of open chain between the top of the guide pulley and the underside of the cassette cogs will sometimes grow and shrink to a greater degree with a Shadow der (as the guide pulley shares it's axis with the cage pivot). Cages with their guide pulley axis off center from the cage pivot can, with good design, allow the guide pulley to maintain a more consistent distance from the cogs. Andy.

The cable for the derailleur goes inside the top tube on the bike could there be something wrong there and therefore I have this problem?

Nope, there are 9-speed shadow derailleurs, I own one and it works fine with my 10-speed 105 road shifters.

If it's a 10 or 11 speed Shadow derailleur, it won't work though, as those do have different pull ratios.

Why did you need to change the derailleur on a new-ish bike, and did the old one work right? If their was a problem like a bent hanger or cable friction swapping derailleurs will not alleviate the problem. Perhaps the Altus derailleur is more tolerant of mis-adjustment

I wonder if the shop did not route the shift wire the right direction around the anchor screw. It needs to go over the little tab next to the screw. If routed the wrong way it changes the lever arm length which affects the shifter movement per cable pull.

When diagnosing shifter problems, excessive cable friction is 1 possible cause. If the cable is rubbing against something that it shouldn't, the extra friction can make shifting into harder gears not go smoothly.

Shifter-derailleur mis-match is another cause.
Bent hanger is another ....
Poor derailleur adjustment is another

Well the the local cube dealer did replace my derailleur after they putted on new trigger shifters. I did take the old trigger shifters apart and messed them up.

After I got the new trigger shifters the bike fell down and the derailleur did not work and I got the bake to the cube dealer and they tried to fix the gears then they where skipping and not working properly.
I had been riding the bike all over winter with lot of salt, snow and ice on the roads so the derailleur kind of was like wornout.

I went with bike again to the Cube dealer to see if they would do something about it, they changed the derailleur to acera shadow. I tired to see if the gears worked properly but they didn't so I tried to fine tune them but I messed it all up so they did not work at all.

I took the bike to another store that I booked time for originally another bike that I own but decided to let them try to fix the problem and they fixed by putting altus on the bike and chancing he cable and the housing.

Smells like a bent hanger and/or derailleur to me.

Thanks for the help guys. I'm going to talk to the different mechanics where I live and have them look at my bike to see if they can find out why only the Altus worked.