In my experience the different grades of Transmission cassettes are really good in terms of durability. My GX is 5000km old in piss poor riding conditions (mud, snow, more mud, salty roads, mud), on the 4th chain, and looks and performs as new.
Know of several high mileage riders on Transmission cassettes, non had to replace the cassettes yet. Except for one, but he had like 15000km of bikepacking trips and ultra races on it
Can I ask why you are interested in transmission? Personally I had it and went back to mechanical. But I know people who love it too.
Been quite a few reporting the GX derailleur has had some problems with the pin. May want to see if you can find a xo on sale if you are set on it.
Or save money and upgrade to XO1 Mechanical! 
I am a GX cassette guy on regular Eagle (MTB and gravel) and use GX cassettes on transmission with my newer XC bike. While I have no experience with NX, it sounds like something is off if you are replacing cassettes at 700 miles. Maybe NX cassettes are really that bad, but I canāt believe SRAM builds a cassette like that. Normally, Iād ask if you are letting your chain wear too much between replacement (which can cause premature cassette damage), but chains donāt wear in 700 miles either and even an old stretched chain shouldnāt significantly hurt a cassette in only 700 miles. I guess anything is possible if conditions are gritty enough, but I ride in all kinds of stuff and canāt imagine the expense of replacing a cassette every thousand miles or so. How are you determining that the cassette went bad in 700 miles? If itās a shop, do you trust them? My first reaction was that it sounds like a shop wanting to sell a cassette. Unless you are bending teeth, the only thing that normally goes bad on a cassette is tooth wear that causes the chain to slip under load (but it usually still shifts fine).
Anyways, Iāve never had to replace a GX cassette and has 10ās of thousands of miles on a couple of them. Iām pretty new to transmission (last year), but certainly have thousands of miles on my GX transmission cassette and I just assume itās going to last like the old eagle ones do. I do wax my chains, but even when I used regular lube I never had a cassette on any bike last less than ~20k miles. For me, the main reason to spend extra on the higher end cassette is the weight. The juice isnāt worth the squeeze for me personally, but they are significantly lighter.
The NX cassette is that bad! I snapped a tooth on mine after a few hundred miles.
Yeah, that will certainly cause shifting issuesā¦ Iāve done that on a couple 11speed sram cassettes, but never on eagle. Iām not sure if thatās me being more careful or the eagle system is less prone to bending teeth. One thing I can say for transmission is that it actually shifts better when you are torquing it hard when shifting. When I first got transmission, I thought it was OK, but not anything revolutionary. Iām still not sure Iād call it revolutionary, but whenever I get back on regular Eagle, I have to re-train myself to make sure Iām not pushing too hard when shifting (never even realized I timed my shifts to happen on the dead part of the pedal stroke). My preference for transmission now is strong enough that I really want a UDH gravel frame so I can ditch the old Eagle.
Anyway, back on topic - Iād be very surprised if you could find a way to bend a cassette tooth on a GX transmission cassette. The system seems to thrive under heavy torque when shifting.
Yeah Iāll admit, Iām not the best about keeping my chain clean/lubed and do ride in some sloppy conditions, but on the other hand I put way more miles on my road bikes with Shimano cassettes and Iāve NEVER needed to replace a cassette on the road bikes.
I donāt particularly trust my LBS to not upsell me, but there was visible wear on the NX cassette. Although, I asked them to replace it with a GX cassette and for some reason they went NX again, after the mechanic trash talked the quality of the NX cassette.
I assume the cross chaining of 1x and the aluminum used in big range cassettes makes them wear faster. Iāve recently switched to waxing chain and hoping Transmission will help as well.
The pandemic forced me into a GX AXS derailleur to replace my XC bikesā OEM NX derailleur that I snapped in half two weeks before a race. The only SRAM 12 speed parts I could find were GX AXS or XX1 mechanical. I chose to try out wireless, and am very happy with it. Eventually bought a new 105 Di2 road bike too and love that bike too.
Long story short though, I just bought a trail bike that came with Non T-Type GX/X01 kit and Iām going to swap that onto my non-UDH XC bike to replace a bunch of aging kit and the Trail bike is going to get a Transmission groupo.
I think the NX cassette uses the HG free hub body and GX uses the XD. Without a new freehub body you couldnāt use GX. Might be why the shop didnāt say nice things about NX, but they still used it.
Good call on the freehub. I feel like I knew that, but had forgotten.
Exactly. Many hubs will have an option to swap the freehub to a XD driver, but thatās usually another ~$100 and not something they are likely to have sitting on the shelf. Much easier to just stick a new NX cassette on and move onto the next bike.
On Eagle the difference between GX and X01/XX1 cassette is really something, GX wears out many times faster and you can feel the shifting not be as crisp even when new.
Exactly. I have a mechanical GX Eagle setup (shifter, RD, crank) with XX1/XO1 cassette, chain, chainring. The nice stuff is definitely noticably lighter, shifts better (crisper with less noise/rasping), and Iāve never worn out the cassette or chainring. NX cassettes are boat anchors but are a necessary evil if you only have HG FHB installed. I typically pick and choose where I spend my dollars/grams-saved money and Iām not even a weight weenie 
.
Somewhat of a repeat post - but put my XC wheels back on for the first time since I upgraded to FA and I think Iām officially ādoneā with this build one year later.
Final tally -
CervƩlo ZFS-5 120, Size Large
23.5 pounds as pictured with pedals, cages, all 4 AXS batteries, 2 AXS controllers, computer mount, 100m of fresh sealant in each tire.
Obviously you could go way lighter with different spec choice but Iām happy where itās at.
Hey all,
Just picked up one of the Epic 8 Pro frames in the recent sale. I looked up Flight Attendant to see what parts numbers Iāll need and the recs to set up the bike as an Epic EVO are a 140mm fork. I was surprised to see that since I thought it was a 130mm frame. Anyone know anything about this? For those racing XC mtb, do you think FA is good enough to run larger suspension and still be competitive?
Thanks!
There is no Epic 8 Evo Flight attendant.
The Epic 8 Evo is the same frame as the normal Epic 8 but with Fox suspension and a longer travel (130mm) fork.
You could make a Flight Attendant build but youād have to buy both the shock and the fork and replace the existing Fox shock that came on your frame.
For the FA XC (Sid ultimate) shock/fork the max travel today is 120mm. So youād just be building a ānormalā (non-Evo) Epic 8 but with white paint. Nothing wrong with that.
SRAM makes trail forks with FA as well like the Lyrik that you can get down to 140mm, but youād still have to pair that with a FA shock and I donāt think the Epic 8 frame was designed for a 140 fork so I donāt think thatās a great idea.
Long story short, you can have FA or āEvoā, pick one.
Where did you read those recommendations? You certainly CAN set it up with a 140mm fork but at what point do you not just wanna get a trail bike?
From Spesh the Epic Evo comes specced with a 130mm fork. If youāre looking to race XC Iād stick with 120/120.
That was the rec from the FA website itself when I looked for the part numbers I needed. Anyone set up 130mm FA on a Specialized Epic 8 and still feel like it was fast like an XC bike?
There is no 130mm sid and therefore there is no 130mm FA XC.
You can get Pike with FA at 130m but thatās a trail fork. Itās 300g heavier than the Sid.
Weight isnāt the end of the world, but what youād end up with would be more like a killer light duty trail bike.
the pike is what sram website indicates for the epic evo, I havenāt looked to see if the shock has a different tune for the EVO vs the non-EVO epic
thatās really good weight! are those M6 or M5 bars, Iām guessing those are lightweight Nextie wheelset if I remember correctly
