There are a few versions of the GX rear derailleur. Which one do you have exactly?

 

Not going to work IME. A 11 sp derailleur should work fine with your shifter but the 10sp for both SRAM and Shimano was sort of a bridge between 2x and 1x and they do not have the range that 11 has. You might be able to compensate with a goatlink or the garbaruk extended cage if they work with that derailleur, but otherwise you're in new derailleur territory to work with 46+.

 

Didn't SRAM change the pull ratio from exact actuation to X-actuation when they came out with 11psd MTB stuff?
Although 11spd road still uses exact actuation, and Apex 1/Rival 1/Force 1 rear derailleurs are the same as the MTB rear derailleurs (with a barrel adjuster).

The 11spd rear derailleurs will work with a 46T for sure, IMO that's a much better solution than getting a hanger extender, but it's more expensive as well of course.

 

I went from an 11-36 to 11-42 and now 11-45 on my Shimano XT M770-SGS 9sp RD setup by adding a WolfTooth RoadLink:

RoadLink install:

11-45 install:

Chain will go slack in small front ring in cogs 6-10, but I don't use those combinations.

Per Shimano, only good for 34T cassette and 33T capacity and I have 34T difference on the cassette and 24T difference on the crankset.

 

HollyBoni I have a SRAM GX TYPE 2.1 10 SPD REAR DERAILLEUR size Medium cage. Works great on the 11-42T 10 speed Sunrace I have now.

 

These were originally designed for a 36T max (not 42T, you were probably looking at an 11spd GX spec sheet, I don't think 42T cassettes even existed when these derailleurs came out). I know they work with a 42T but I wouldn't push them further.
I'm not a fan of these but you could try a hanger extender. You can get more expensive ones from Wolftooth or dirt cheap China ones. You'd be better off with a SRAM rear derailleur from the 11spd generation, these have an offset upper pulley and they work much better with wider range cassettes. Of course that's much more extra cost. They're 1x specific but i'm assuming you're running a 1x setup?

Random China hanger extender example:
https://www.aliexpress.com/item/329...5981310661294069edaa7&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

Wolftooth:
https://www.wolftoothcomponents.com/collections/drivetrain-1/products/roadlink

 

I am set up 1x10 so I'm good that way. The vids and literature say that the Sunrace 11-46T comes with and extender. It seems like the plan will be ---- buy the 11-46T... try it... and IF I can't get it to work... go to plan B --- a different derailleur. I was hoping to confirm that what I had would work, but it seems I need to realize that I may have to pay the $$$ for a new derailleur.

 

I'm sure you'll be able to make it work with a hanger extender. The difference is that with a newer rear derailleur you'd get better shifting, whether it's worth the extra cost is another question.

 

So you're saying the SRAM NX 11 speed derailleur is a better solution for shifting a 10 speed 11-46T? If I can't get my current GX 10 speed derailleur to work that may be the solution?

 

An NX, or any other SRAM 11spd MTB rear derailleur won't work with your shifter. I know, it's weird, i'll try to explain.

In the SRAM world, on 10spd both the road and MTB stuff used the same pull ratio, exact actuation. I don't know which came first, but when 11spd road stuff came out, it stayed on the same exact actuation pull ratio, but when 11spd MTB stuff came out, SRAM introduced a new pull ratio, x-actuation. Every 11spd SRAM MTB rear derailleur uses X-actuation, these won't work with your 10spd shifters.
However, SRAM came out with 11spd CX/gravel groupsets, and these use rear derailleurs that are pretty much exactly the same as their 11spd MTB rear derailleurs, AND they use the older exact actuation pull ratio, so they will work with your shifters. These groupsets are Apex 1, Rival 1, and Force 1.

These newer rear derailleurs were meant for a 42T cassette to begin with, and they have a bit of a different design which works better with wider range cassettes. A lot of people use them with 46T or even bigger cassettes and they work great.

 

Cool so it sounds like I have options if I need them.

 

Regular GX won’t work with 46 or higher, you need the eagle derailleur.
Shimano on the other hand, deore m6000 will work up to a 50T . It will wear the derailleur pivots quicker, but they’re pretty cheap.

 

Regular GX won't work with 46 or higher, you need the eagle derailleur.
Shimano on the other hand, deore m6000 will work up to a 50T . It will wear the derailleur pivots quicker, but they're pretty cheap.

Not sure what you mean by regular GX. The older 10spd one that the OP has will probably struggle without a hanger extender. But SRAM 1x specific rear derailleurs from the 11spd generation will happily work with a 46T, lots of people use them with 46T (or even bigger) cassettes. No need to go Eagle for a 46T. For a 50T Eagle would be more ideal, but Eagle RDs won't work properly with 10spd SRAM shifters anyways because of the difference in pull ratio.