I was confused by the Trek naming convention when I first saw it. There is actually a 2023 Rail 9.8 XT Gen 3 and a 2023 Rail 9.8 XT Gen 4. The Gen 3 being a carry over from 2022. Both use smart system, Gen 3 has Kiox, Gen 4 has System Controller mounted in the top tube.
Honestly my lap times are not any faster with the 38 vs yari with 170mm air shaft. The 38 feels and works much better though, especially banging rock gardens in the mountains. I imagine the ZEB also works well.
If you are using a rock shox fork on your Rail, I highly recommend the 170mm air shaft (cheap upgrade). The Debon air design is crap (sram). The updated design is a little better at maintaining ride height but still not great. I switched to a Fox 38 170mm several years ago. My new Rail came with...
I know this is an old post, but the new (for 2022) Line Comp 30 wheel is a downgrade from the 2018 Line Comp 30. The hubs are the same. The downgrade is the rim. It has a lower profile (24mm vs 20mm), but the real issue is that the new rim is sleeved instead of welded like the 2018 rim. I bought...
I will add that in addition to the T-40P (plus) bit, it helps to have the security penta-lobe driver bit in your toolbox. There are six (6) penta-lobe fasteners on the motor mounts that eventually come loose (for me average of 1500 miles). I put a drop of medium thread-locker on them