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More Eagle GX 12 Speed Details – Adjustments, Chainline, Racing it

More Eagle GX 12 Speed Details – Adjustments, Chainline, Racing it


Hi everyone after riding the Eagle for a
little while, long enough to get some battle scars here on the derailleur, I thought I will give you a few more of my findings, all kind of stuff that I
couldn’t fit in that installation video. So here we go. Quick look at the shifting performance after about 100 miles or 150 km Pretty much the last three races of the season. You saw the issue with the 42t, being a bit out of sync. Upshifts are really smooth. If you look at the cassette here you’ll see that especially this aluminum 50t is getting scratched up quite a bit, quite quickly. You look at a coating
here, it will show some use right away. The chain getting out of sync with this
42 and 50 tooth cog seems to be random and it would only happen on the bike stand. I did not experience it on the trail and in talking with my local bike shop they didn’t see it on the trail either. But it is reproducible on the stand. This seems
to do with the B-gap adjustment over here. One of the reasons why SRAM
introduced this adjustment tool with all their new derailleurs but it’s kind of weird that it is so sensitive, so it might have something to do
with their design as well. You can see that I might be 1 mm under that line, the reason why I set it up like that is so when I sit on the bike and my derailleur moves a
little bit under my weight, the top jockey just goes further away from the cassette. So for those of you that didn’t get this little tool, take a ruler, and that is
your 15 millimeter from the line down to where this next tooth of the upper
jockey is supposed to be. Here is that approximate 15 mm, remember SRAM
recommends doing this under sag so sitting on the bike while you measure it. If you’re using an oval SRAM recommends having your crank at 4 o’clock, if you
remember they recommended having the crank at 1 o’clock when measuring the chain. Chainring at 4 o’clock, that means the widest portion
north/south, that’s when you adjust your B-gap here. The difference between the crank at 1 and 4 o’clock is about 1 millimeter here in B-gap adjustment. The only reason why you want that big gap to be just right is because otherwise you can deteriorate the shifting on the smaller
sprockets as well. One of the issues that the 11 speed systems were plagued with was back pedaling on the biggest cog. On this one, I can backpedal as much as I want, This is not gonna come off, that is despite
the fact that the 50 tooth as you remember is pushed further in here, about 3 more
millimeters in. And that makes for quite extreme chainline. That’s the chainline
guys it’s pretty extreme as you can see, Look at that angle of the chain… Looking at the derailleur, with the cage locked/extended you get about 5 mm of play. Most of this play seems to come from that B-knuckle where it connects to the derailleur hanger that’s supposed to be improved or redesigned. I did check an X01 in the bike shop and that one had a lot less play but still had a little bit. This doesn’t seem to affect the shifting in any way but there is a clear possibility that I don’t know any better since this is the only 12 speed
that I’ve used for a longer period of time. Chainline on my bike is on this
6th smallest cog, and with the chain over there in the middle of the cassette, non Eagle chainring, you’re gonna see that the chain engages with the narrow-wide
profile really nicely, I had no issues with drop chains or chain retention in general. I assume that all the advancements in chain technology are to be felt at the extremes of the chainline. But overall I think that the chain is probably the most refined part in this new 12 speed. By the way, the chain
comes with a gooey type of oil on it, so you might want to clean that out before installing. Yes, I finally got my Eagle GX chain, so here’s the 12 speed next to the 11 speed PC-X1. You can see the coating here on the two
chains, is identical, so if you were happy with a PC-X1 type of chain before, I’m sure you would be very happy with the SRAM GX Eagle chain. These are both made in Portugal at their facility. I did like the feel of this X01 shifter better than the GX and since I had both , I did install this one. I don’t regret it, I tested my drivetrain back-to-back with an XX1, and they were very very similar
in feel. Most of that I’m sure comes from the shifter. Now, the one feature that is
a bit gimmicky is gotta be this ability to move the angle of your down lever. 3 mm Allen key, loosen that one up a little bit and this starts to move up or down. You can’t move it down much because once you do that, it’s in your
way, you can shift up anymore. If you move it up too much,
then the ergonomics are gonna be pretty bad so if you’re happy with the way that
GX shifter feels, even though it doesn’t have this feature, I would definitely go
for that and save quite a bit of money. Pretty much used this drivetrain for the
last three races of the season and the training in between, and if I am to summarize it it would be Smooth, quiet and reliable. Absolutely loved the bike with this extended range. It definitely saved my bacon especially in the last race relay of the season. It was the race when I abused it the most and it worked flawlessly. So all in all I am happy that I’ve chosen
the fully baked solution as opposed to a hybrid 11 speed. Looking forward to see what Shimano is going to come up with whenever they introduce something similar. If you guys want to buy any one of these products just use the links below, let me know if you have any comments or questions, don’t forget to like the video, keep an eye on my channel and social media. And until next time, I will see you on the trails guys. Cheers!

48 comments on “More Eagle GX 12 Speed Details – Adjustments, Chainline, Racing it

  1. I have not experienced at all the problem you mentioned with the pinions 50 or 42. If it is true that the change to or from the pinion 42 is not as smooth as the rest. Have you tried with the B Tension screw?. My transmission is completely XX1 Eagle, and I love it. Chainring between 34 or 32 teeth.

  2. The sync issues could be the outcome of the derailleur hanger which is maybe not perfectly aligned. Eagle drivetrains are very sensitive in such a case. With a derailleur hanger alignment gauge like the Park Tool DAG 2.2 you can check if the derailleur hanger is misaligned.
    I checked my 2017 Trek Fuel EX derailleur hanger (same like yours: 301805) and it was misaligned right out of the box. But before I'll try to bend it until it's straight I'll mount the GX Eagle drivetrain to see how it performs.

  3. My bike shifts fine upside down but when riding it shifts terrible lol wtf… is that?
    Hanger is perfect, b screw is just right, indexing is spot on. I dont get it. When riding it hesitates badly shifting down the casset mostly in middle of the cassette. 4-6 th gears. System is 1.5 years old, chain is new, cable pull is super smooth when diconnected from the rear mech. This blowing my mind.

  4. I have the eagle gx on my stump jumper and the hanger must be perfect as my one was out on a new bike. Also the B tension also must be perfect and done with 20% sage in the stand . Let the air out of your shock and compress your rear swing arm with a strap. And also the xx1 eagle shifter has also a bearing for a smoother feel then the gx one. Also buy a durace road shift cable as it improves the shifting.

  5. Love your videos man! Another EXCELLENT review and tips and hints with problems or "what-could" or "what-if" explained within your video. You're the MAN!

  6. The rear mech location needs a big design change. I would like to see it above the axle or at least 50% of it above the axle. These things are getting monsterous all dangling down by every stick, rock and root. Imagine this on a 26 in wheel? Almost scraping the gound. I would like to see frame and mech builders get something going. Its been a long time comming. Something smart, easy and durable. 2017 rear derailure disgn is a low hanging fruit! lol
    Great channel

  7. Great job brother! I can always count on a super thorough review that covers everything I could possibly want to know…. I'm glad you're happy with your GX. I'm still on the fence as I may wait another year to see if Shimano throws their hat in the ring and also to see if SRAM cleans up some of the rough edges on their design.

  8. Another nice video. Ever since I had a Chevy for a year instead of my usual Toyota/Nissan, I've learnt that American engineering is not as good as Japanese engineering; not surprised then that SRAM has been marketed and hyped beyond it's true level of quality. Shimano is engineered to higher standards and where I ride, anyone with SRAM has problems and those with Shimano have none.

  9. Currently with a 1×10 sram group set should I spend 200$ for a 1×11 or should I spend 400$ for a gx groupset ?

  10. That extreme chainline made me go back to 2×11. Climbing for more than an hour in the Alps…, it just irritated me and I'm sure you lose some watts by it. I think that's the only real downside of a 1x drivetrain. Or should I just ignore the chainline? I'm in doubt 🙂

  11. LoveMTB I’ve been having these same issues with my GX eagle and will take a look at the B gap. Interesting you mentioned the back pedaling, when I’m on the 50t I can’t back pedal more than one half rotation without dropping chain. This has proven to be problematic during really technical ascents. Any thoughts on tuning to prevent dropping? Great vid!

  12. seems like the same issues with the GX derailleur first gen. Loose pivot joints, play, durability….This is why I chose my trance 2 over the trance advanced. I'll take shimano over sram any day, but that's just me.

  13. Very nice info and the videos are very entertaining and they has good quality! Love the channel, continued doing this stuff!!!

  14. Say… Concerning that chain line @03:00…

    I recently upgraded my Bike from a 2×10 to a 2×11 but unbeknown to me the Di2 Front Derailleur I bought is incompatible with the Crankset because it not supporting the Boost spec standard the Crankset has ( +3mm ). I'm not exactly too familiar with what else the Boost spec standard defines other than providing a better chain line with the sprockets on the rear wheel.

    For the moment I'm keeping the FD shimmed to achieve near Boost spec required distance from the frame but at some point or another I'll also replace the Deore Crankset for either an XT, maybe even an XTR, one and when I do I plan to buy a Non Boost specced one that would allow me to remove the stack of shims from the FD.

    My train of thought is basically that if a 1×12 can cope with such an extreme chain line then a more forgiving 2×11 should easily be able to cope with a slightly less ideal chain line caused by using a Non Boost specced Crankset in combination with a Boost specced rear wheel hub?

  15. Hello. I was amazed on how you could backpedal with no problems on the chain jumping from the largest sprocket to the middle of the cassette. I have only used it twice… how do you accomplish this perfect backpedaling?

  16. Thanks for the great install video. I spent the afternoon installing my new group – GX kit. I am struggling with the B adjustment and I think it has to do with the mounting on my bike – bike is a Rocky Mountain Pipeline 2017, 770MSL. I have the B adjustment fully in and I am seeing the derailleur/jock binding into the cassette when shift to the 50t side of the cassette range. Wondering if I missed something? Or any suggestions on what to look for.

  17. buenas tardes, tengo problemas con la transmisión, una ves regulada en el taller los cambios funciona perfectos, pero a la hora de salir a andar cuando subo los piñones va bien pero le cuesta bajar los piñones y otra cosa que hace, es que suele saltar la cadena en el piñon, no pasa a otros piñones sino que salta sobre el mismo, opciones para solucionar los problemas, muy bueno el video. saludos Gracias

  18. Great video. I have a technical question that no bike shop seems to be able to answer. I hope you can help. I have a 29 inch Cube LTD 2014 mountain bike fitted with slick tires that I want to dedicate exclusively to asphalt riding, and I wanted to have the 12X1 described in the video but with bigger gears. So the question is if I can use the Sram gx eagle groupset, but instead of the gx eagle crank and ring, install a Sram Rival 1 X-Sync 10-11 speed Compact GXP crankset with a 50 tooth chainring. This ring also has the narrow wide profile of the teeth, so I think it should work with the 12 speed chain. The set up would take a rather long chain to accommodate a potential 50/50 pairing, but assuming that there are no clearance issues with any part of the bike frame, is this feasible? Thanks!

  19. I just installed x01 and I can't adjust the low set screw to the center of the biggest cog it just won't move the derailer far enough left any suggestions?

  20. I had the same issue and after working with it for a while and not getting past that strange alignment issue I ended up taking out a link on the chain and that fixed the problem completely.

  21. I have a question, my gx eagle keeps tightening its cable tension and not going into 10+ gears, why?
    It is stored so nobody can nudge it or bump it.

  22. Hey! I have read all posts but did not find anything that relates to my problem. I have a hardtail with GX Eagle with 1k miles on it. 10, 11 and 12 gears are very loud or noisy. Not so much when padeling forward but backwards its unbearable. It also looks like chain rubs to larger cog when backpaddeling. I tried to move H limit screw even more outwards but it does not help and only causes problems in middle range of gears. B-gap is at 14mm as stated in manual. What else shoud I look for? Chain is not worn out and is within limits (less than 0,8% worn). Rings looks ok as well. I believe system should not be worn out after 1k miles. Right?? Thanx!!

  23. I bought the new KCNC 9-52 cassette from R2 Bike and the chain falls in the last 3 big cogs when doing backpedal. I put on a new chain and he keeps doing it. Crank at the front is a 32t boost 3mm offset. My bike is a Specialized Epic Expert 2018 1×12 full Eagle XX1 and had no issues with the Eagle 10-50. It seems as the chain looks crossed. Somebody told me to use a 6mm offset chainring other told me to use a 28t instead of a 32t. Also I don't know why the last 3 cogs skipped the chain on torque when the chain is new

  24. The out of synch issue is due to their quality production I bet you cassette wobbles quite a lot! I had the same problem and it even reproducable on the trail. I bought another one, luckily it doesn't wobble as much and this issue is gone.

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