GX Eagle - shitty shifting solved!!
- Thread starter Haakon
- Start date
steve jobs' pancreas
Eats Squid
oooh it comes in gold (the b b b b bolt)
I'm on that sucker !!!
I'm on that sucker !!!
droenn
Fat Man's XC President
I first thought SRAM were being dodgy (they probably still are) - but I like the idea of getting decent shifting for much cheaper than XO more.
I'm yet to try GX (currently have X0), but coupled with a KMC chain and Sunrace/Box cassette might be the way forward...
Nambra
Definitely should have gone to specsavers
Hard to say - maybe the fact that the B knuckle is sloppy creates variability in the alignment of the jockey wheel axle from 1st to 12th gear. In other words the upper jockey wheel is not perfectly in vertical alignment with the respective cassette cog across each gear. Let's see if a picture will help:
Forget the purple and green lines - it's chopped out of a SRAM 1x11 install instruction sheet so they're not my work. Perhaps the sloppiness of the B bolt in the knuckle (small curvy orange line with arrows) causes the derailleur knuckle to change alignment with respect to the wheel axle (red line) and effectively rotate around the blue dot ie. inside the mount somewhere. The small deviation is amplified at the cage/jockey wheel (big curvy orange line with arrows) and it doesn't remain aligned with the cogs at the extremes of the cassette (dashed orange lines showing jockey wheel toe-in). You tune it to work at one end (say the 50t 'cos it's usually the most painful end to get right due to the 42t-50t jump), and it leaves you with piss poor shifting as you downshift toward the other end.
Enter your eagerly anticipated X01 B bolt and the knuckle is rock solid in line with the wheel axle, the derailleur cage and jockey wheel remains much better aligned with the cassette and shifting is silky smooth across all gears.
All speculation of course, and I'm no mechanical engineer so it's likely I'm talking through my arse, as usual.
Forget the purple and green lines - it's chopped out of a SRAM 1x11 install instruction sheet so they're not my work. Perhaps the sloppiness of the B bolt in the knuckle (small curvy orange line with arrows) causes the derailleur knuckle to change alignment with respect to the wheel axle (red line) and effectively rotate around the blue dot ie. inside the mount somewhere. The small deviation is amplified at the cage/jockey wheel (big curvy orange line with arrows) and it doesn't remain aligned with the cogs at the extremes of the cassette (dashed orange lines showing jockey wheel toe-in). You tune it to work at one end (say the 50t 'cos it's usually the most painful end to get right due to the 42t-50t jump), and it leaves you with piss poor shifting as you downshift toward the other end.
Enter your eagerly anticipated X01 B bolt and the knuckle is rock solid in line with the wheel axle, the derailleur cage and jockey wheel remains much better aligned with the cassette and shifting is silky smooth across all gears.
All speculation of course, and I'm no mechanical engineer so it's likely I'm talking through my arse, as usual.
tkdbboy
Likes Dirt
Anyone running a Sunrace derailleur?
Specifically this one (https://www.hibike.com/sunrace-mx-6...02467fd9516546c1544cdbd51d49eea5#var_78440006 )
It says its a med length cage and supports the 12sp cassettes which run 50t , but my understanding is that med cages don't easily work with 50t out of the box?
Has Sunrace designed their med cage derailleur to work with 50t?
These HiBike price points are super tempting to go back to 11sp!
Fun fact: The 11sp 50t cassette has the same top 8 gears as Eagle cassettes
Specifically this one (https://www.hibike.com/sunrace-mx-6...02467fd9516546c1544cdbd51d49eea5#var_78440006 )
It says its a med length cage and supports the 12sp cassettes which run 50t , but my understanding is that med cages don't easily work with 50t out of the box?
Has Sunrace designed their med cage derailleur to work with 50t?
These HiBike price points are super tempting to go back to 11sp!
Fun fact: The 11sp 50t cassette has the same top 8 gears as Eagle cassettes
hellmansam
Likes Bikes and Dirt
Yeah but......wouldn't there have to be some play in the mounting pivot to allow the movement depicted by the curved orange arrows ?
gillyske
Likes Dirt
yes please. would love to hear more opinions of the ztto cassettes
Nambra
Definitely should have gone to specsavers
Relative to X01, there is definitely a looser fit with the GX derailleur and GX B bolt - if you wiggle the cage at the lower jockey wheel on the GX derailleur there is definitely more play and it seems to be mostly as a result of movement at the B knuckle where the (inferior GX) B bolt attaches it to the hanger. It's not so loose that it is rattling around at on the GX, it's just that there is noticeable extra play compared with X01 - the B bolt is less snug in the derailleur knuckle.
Comparative detail between the two derailleurs:
Note that the B tension plate between the derailleur knuckle and the hanger also differs between the two - X01 is machined by the looks of it, with the GX stamped and perhaps less precise. You can also see the orange o-ring between this plate and the derailleur knuckle on the X01, which probably also helps to keep it all solid.
If @Haakon's original post is anything to go by, eliminating play in the B knuckle by using the X01 B bolt, connecting plate and o-rings, provides a more precise feel with GX. This video provides a good comparison between the two and also mentions the play in GX that X01 doesn't have.
I'd suggest it's the wavy washer / split ring B bolt system that GX has that introduces play (this video helps to explain why - there's always going to be a little play with this system). I'm tempted to grab a X01 bolt kit from mtb direct to try for myself, but I'm thinking maybe a pair of simple o-rings might achieve a similar outcome for less of an outlay. I wonder if you could keep the GX B bolt, ditch the wavy washer and use an o-ring system on the GX B bolt and get it nice and firm like the X01 setup?
Yes this is splitting hairs and I'm being a total nerd, but there is definitely a superior shifting feel with X01. If this is because SRAM has made GX feel crappier than it could otherwise be (to sell more X01 at a premium?) for the sake of a few cents difference in parts, then I'm curious to find out.
Edit: it appears you can get a black XX1 Eagle B bolt kit from 99 bikes - click and collect, no postage: https://www.99bikes.com.au/sram-xx1-eagle-rear-derailleur-b-bolt-limit-screw-kit-black
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wkkie
It's Not Easy Being Green
I'm looking for a replacement for the Microshift at the moment and looked into that derailleur. I found some info on exploding jockey wheels or similar and at the moment I'm thinking I'm just going to stick with XT...
Box 2 was my other option, but it's about $60 more than XT, so hard to justify...
Hi Nambra, peeps on MTBR have solved issues with GX by using the XX1/X01 bolt
"So I put the XX1 (same as XO1 but gold) bolt on the GX derailleur and it fits well. The back and forth movement is a bit stiff but it does not seem to be a problem, this could probably be solved by leaving one of the seals out. Most importantly there is no wobble any more and shifting is really precise. I'll get one for my other bike, too."
XO1 Derailleur bolt on GX Eagle?
forums.mtbr.com
Nambra
Definitely should have gone to specsavers
Yeah I read those comments on mtbr. I'm waiting on @Haakon to get his bolt and report back before I commit to it. I still think you could probably just add an o-ring to the existing GX bolt for a similar outcome for bugger all money... I might try that in the meantime if I can find some suitable o-rings.
Haakon
has an accommodating arse
Not sure that'd work - its not end play thats the issue, its the shitty tolerances between the bore of the body and the bolt itself.
* I think. ie yes wait until I can confirm!
Nambra
Definitely should have gone to specsavers
I wonder if there is any difference in the derailleur knuckle between X01 and GX - is the GX one not machined to as close a tolerance? I guess if the X01 B bolt makes for a more secure connection, it would suggest that it's just the GX B bolt that is less snug, not the derailleur knuckle.
Haakon
has an accommodating arse
This is my thinking. The X01 has a plastic bush/sleeve that is there to handle the poor bore tolerances.
Stay tuned
teK--
Eats Squid
I'd probably just buy it from mtbd to be honest. After the change rate and GST the difference is like $2
Flow-Rider
Burner
What Mail carrier did you use ?This is my thinking. The X01 has a plastic bush/sleeve that is there to handle the poor bore tolerances.
Stay tuned