You watched us smash SRAM Transmission with the equivalent of a hypersonic baseball, you watched us try and drown it underwater, and you watched us send it to outer space. It survived it all.

Well, it actually did break a little, but it was a $20 fix and I’ve been running that same derailleur on my Revel Rail 29 ever since, and loving it.

SRAM X0 Transmission on my Revel Rail 29. Still chugging along after the beating it suffered in our testing.

Most of you have probably not run out to upgrade to this $1,600 drivetrain, and I don’t blame you. In fact, one of the things we discovered in our derailleur smashing video is that even the regular AXS derailleur is insanely durable, and I personally have rarely had issue with a normal mechanical drivetrain. But, as SRAM is wont to do, they have once again trickled down their latest and greatest technology into a more affordable GX version.

Let’s take a quick look at this $1,099 groupo to see what the important differences are to help you determine if you might want to upgrade to a Transmission drivetrain (or possibly put it on your new custom mountain bike that you assemble in our Bike Builder tool 😉)

The all-new SRAM GX Transmission

GX Transmission Cranks:

The derailleur is of course the most interesting part of this whole groupset, but since you do have to run an entire T-type drivetrain (that’s Transmission type), I’ll run through the other GX components first. All Transmission components will eventually be available individually if they aren’t already, so you can mix and match as you please.

The GX cranks are forged aluminum and have a similar aesthetic to the X0 cranks, although are much more rounded. I read some concerns that X0 cranks look so sharp that they may bite your ankles; although that’s not something I’ve encountered yet on my bike, if you are worried about it, this may be the ticket.

The GX cranks (left) are more rounded than the sharp X0 cranks

They come with a removable composite bashguard on each side of the chainring so that whether you ride left or right foot forward your chain is protected. One thing to note is that if these guards make your chainring incompatible with an upper chainguide. They are also not compatible with the DUB Power Spindle power meter, but can be used with the slightly less accurate spider based power meter. I imagine that if you want to get the most precise power measurements possible you’re also running the lightest gear possible, so this likely won’t be an issue for the majority of people.

GX Transmission Cassette:

The GX model cassette is much shinier than the more expensive models, and that is because they used an electrolytic process to cover it in nickel. This coating adds durability and hardness to the stamped steel cogs. That does differ from the X0 cassette, which uses an electroless nickel plating process for its finish, which is a bit harder, has more lubricating properties, and of course is more expensive.

The GX cassette (left) has an electrolytic nickel coating and four cogs machined from the same piece of steel, whereas the X0 model has an electroless nickel coating and nine cogs machined from the same piece of steel.

Unlike the X0 model, more of these cogs are pinned together instead of machined out of the same piece of steel. That cassette had the smallest nine gears made of the same chunk of metal, whereas on the new GX model it is only the smallest four. This results in 64 grams of additional weight.

GX Transmission Chain:

SRAM has claimed that their T-type flat-top chains are the strongest chains they’ve ever made, and they’ve kept that design with the GX drivetrain.

It doesn’t have the fancy coating or hollow pins that the XX model has, or the cool looking black finish that the X0 model has, but it’s fully e-bike approved and at $50 it is a whole $100 cheaper than the fanciest XX SL model chain. It also weighs almost the exact same amount!

GX Transmission Derailleur:

And finally, we arrive at the new GX derailleur. It seems SRAM listened to the folks who worried about that battery getting knocked off—not something I’ve experienced or heard of happening, by the way—because they’ve taken the battery off the back and stuffed it inside this whole assembly. 

To accomplish this, SRAM sourced a different, slightly lighter motor, and shifted around the gearbox so that it’d all fit. The functional result is exactly the same, but the derailleur looks a bit different. The motor/gearbox assembly is fatter and wider, vs the more slender design found on the X0 and XX models. It’s not a massive difference, and if you did find yourself stressing about the old battery placement, you’ll be happy with this new design.

The new GX Transmission drivetrain is a solid buy if you’re looking to try this tech and don’t need the lightest possible equipment.

Aside from that there are some differences in the materials used, as well as the part numbers for replacement bits. The skid plate and parallelogram pieces are different from the ones for the more expensive models, and the GX derailleur has a steel cage instead of the alloy cages found on X0 and XX, or carbon on XX SL.

The cage is still replaceable, and one neat thing is that you can use any T-type cage on any Transmission derailleur, allowing you to easily drop a bunch of weight if you were to ever replace your cage.

Should I upgrade?

I explained in this video why SRAM Transmission is a big deal. With this GX version it becomes $500 more affordable, and because all the components are compatible with each other, opens up a lot more room for picking and choosing where you want to spend your money. Only time will tell if it’s quite as durable, but based on what I see here, I suspect it is, and possibly more-so.

I know from personal experience how well X0 Transmission performs, and if I were going to build up a new bike, I’d absolutely spring for the GX version. If this is something you think you want to try, and if you have a bike with a universal derailleur hanger, click here to pick up a set. If you’re thinking about building a new bike up, maybe hop on the Bike Builder and see what you come up with. We’ve got GX Transmission loaded up in there, so you can see what your dream build would look like with it on there.

If you have any questions on this stuff, don’t hesitate to reach out to us. Thanks for reading ya’ll, I’ll see ya next time.

• Dan Perl