Rear Derailleur Problems
 

I have a GT backwoods with a shimano acera rear derailleur. I am just getting back into mountain biking, as a child i road BMX and downhill competitively and i realize the bike i got is by no means top of the line. But i've had to take the bike back to the shop i bought it from a number of times. Specifically to adjust the rear derailleur a couple times now. Needless to say i'm fed up with the derailleur.
I've been looking around to find a new derailleur for a couple days now.
My questions are:
How do i know the derailleur is for a mountain bike?
What is a good derailleur for a decent price i should be looking for?
How will i know that it will be compatible with my gear select?

My questions are:
How do i know the derailleur is for a mountain bike?

You will specify Mountain derailleur on the website search engine.

What is a good derailleur for a decent price i should be looking for?

What is a "decent price" to you? More importantly: how many cogs are there on the cassette?

How will i know that it will be compatible with my gear select?

Irrelevant. Get a "long cage" rear derailleur (pretty much a given in a Mountain model). Done.

My questions:
What has the bike shop said when you bring the bike back, still unhappy with the rear shifting? Do you have compressionless housing for the shift-cable? Has anyone checked to see if the hanger or shift cage is bent?

My take: you are scandalized by the 'Acera' branding and you think more money will get you better shifting performance. I disagree. A Shimano Tourney rear derailleur can shift better than anyone except a pro needs. Not that you don't deserve better, but, IMO if you don't learn to make the cheap stuff sing (yourself, LBS mechanics don't always have the patience) you won't be able to make the really good stuff stay on key either. FWIW.

Don't mix SRAM with Shimano. Rear Derailleurs

Except a SRAM derailleur will not work with Shimano shifters, and viceversa. And a 10spd Shimano has different pull than a 9spd so it won't work either. And a long cage is not "a given" in a mountain bike rear derailleur. They have been making mid, end even short cage derailleurs for a long time.

Except a SRAM derailleur will not work with Shimano shifters, and viceversa. And a 10spd Shimano has different pull than a 9spd so it won't work either.

You're right. I took the question a little less literally than you did. My bad. Seriously. I should stop doing that.


And a long cage is not "a given" in a mountain bike rear derailleur. They have been making mid, end even short cage derailleurs for a long time.

Ok... I'm not doubting you, just wondering what the difference(s) would be in that case. IOW, why would it matter then?

From your question's op,, your showing me your skill/knowledge level on this,,,

You should find a local bike shop you like and trust if possible, and let them advise you. For this free advise you should let them do the work...
You will need them again, support them as best you can >>>:P

I ride a 2x10 with a mid cage,,
Hate long cages, too much chain to manage, more noise..

A clutched derailleur is far better for chain management,, just sayin.

Most 10 speed hubs can take an 11,
Shimano M8000 rear mech,,good stuff shifts like expensive stuff,,,$70
The shifter Is critical here,, that's another $50
Teflon coated chains, Jaguar teflon coated cables, This Is how I play,,oh my ~ and on It goes..

If you have a 3x9 your limited,,

See ! This rabbit hole gets deep,, go to a bike shop >>>>>

Thanks yall!
 

First I wanna say thank you for the help, I learned a little from everyone!
Secondly I should have mentioned in the original post that I did inspect the hanger which is not bent but they cage appears to be bent in my opinion! My ring set is 3x8. I learned that with 3 rings in the front a long cage is best to accommodate how far the chain needs to move!

Also
 

I tried to adjust it myself and got it pretty close; it will down shift/to a larger ring perfectly but when up shifting/smaller ring it wants to skip rings!

You mean cogs. The ones in the front are called rings, the ones in the back are called cogs. How old are the cassette and chain? How old are the cables? Have you adjusted the limit screws? There are some decent tutorials about derailleur adjustment online.

If you do buy a new derailleur, a 9spd should work with your 8spd setup.

Yeah sorry new to the termanoligy! I looked up tutorials set the screws adjusted the shift cable. The bike was brand new in May. So that's how old everything is. I plan on taking it to a local shop that does free quotes but I'm essentially convinced that it's not working properly because the cage is bent.

Buy a 9-speed Alivio or Deore.