Deore XT RD - when an upgrade isn't
 

I picked up a new 9 speed Deore XT SGS RD at a recent LBS sale for a bargain price. I hoped this would improve over the existing r453 mech when using a 12-36 cassette. The crankset and levers are all Shimano r453 (Sora 3503) triple, with a 26T granny gear. I use one bike for riding SoCal gravel and road riding and swap wheels/tires and cassettes accordingly. The road cassette is the stock 11-32. Swapping wheels with the old mech was a breeze and required no adjustment to the RD or to cable tension. I could have adjusted the B screw in and out, but I typically I left it screwed all the way in. It wasn't perfect but it worked - I would on occasion experience some juddering when in the 36T. I hoped the Deore would solve this problem, unfortunately it has created nothing but problems, most significant is the increased "cross chaining" in the three lowest gears when using the middle chainring and the stock 11-32 cassette. (Its the same issue with the 12-36, but typically I'm in the 26T ring when using the bottom end of that cassette.) I would experience a little extra noise in the lowest gear with the r453 but the Deore is far worse and the noise arrives nearer the middle of the cassette. No amount of cable adjustment or fiddling with the limit screw has improved this. I have replaced the cable and the hanger. I have spent hours on it. The noise comes mostly from the bottom jockey wheel, which runs very close to inside (hub side) of the chain. Of course I could simply drop into the 26T ring to avoid this. Am I misguided in thinking i should be able to use my middle 39T ring across the whole range of the 11-32 cassette?

Other issues I have encountered: there are now no quick swaps between wheels/cassettes. There is no one single B screw setting that works for both cassettes, and with any adjustment to the B screw then the cable tension is thrown off. Also in general the cable tension has proven to be extremely difficult to set and provide good gear shifts at both ends of either cassette. the r453 RD was much more forgiving.

Besides swapping back to the old mech (which is my fail safe) I'd appreciate any insights or suggestions as to what to look for. Thanks

What is the model of the RD? Is it M772 (shadow), M771 or something else?

I run Sora 3503 shifters with 11-34 cassette and Deore M591 in the rear. Before that I ran RD-5701, it was easier to setup, but M591 also works.

What size are your chainrings, and how are you sizing your chain?

And to repeat the above question, which model it the RD?

It sounds like you've got the newer Shadow style derailleur. I have personally found this design to be more difficult to tune, with the traditional style more forgiving as you describe. Most noticeable with the Shadow design is the higher chain tension, which seems to generate more noise, at least in my case. In addition, shifting wasn't as smooth. I "downgraded" one of my bikes which came with an RD-M3000 (Acera level Shadow) to an RD-M360 (older Acera design) and it's much more pleasant to ride.

Have you checked the hanger alignment, even though it has been replaced? Changing the B-screw shouldn't affect the indexing ("tension" is a misnomer) if everything is correctly parallel.

its the M772 shadow.

chainrings are 50, 39 26 (stock was 50, 39, 30)

Chain is the original size stock size

re hanger alignment - its a new hanger - I'm not sure how to align it past fitting in place



quick edit: i did take the bike to the LBS who fiddled with it for some time. They did not improve on what I had done - but found no issue with the RD, but vaguely suggested this problem could be a compatibility issue

Part of your problem may be the chain wrap capacity. between your two cassettes and that wide range crank, you need a (50-26)+(36-11) = 49t capacity. The long cage (which you have) is - I believe - 45t. Those estimates are usually conservative, but you are definitely close, and when you get that close, the chain length becomes really important. Make sure your chain is sized correctly (big/big + 1..... Google it... and consider your 36t cog your "big"). Since you put that smaller ring up front, you may be getting too much slack in that ring.

If you are exceeding the RD chain wrap capacity it is still OK to use (if you use the Big/Big+1 chain length method), but the smaller ring/cog combos can get wonky.... just avoid them.

that had been my experience with the old r453,

i agree that there is some kind of alignment issue, perhaps exacerbated by the longer cage. I would be tempted to say that the cage appears to angle out and away from perpendicular - that is if i sight up everything by eye and try to confirm with a straight edge, then id say that the bottom jockey wheel is not directly below the upper jockey wheel. its hard to judge

Thanks, that will be my next course of action. I can see how there could be an issue there, and perhaps this RD is just more sensitive to things being not quite right. Im still perplexed as to why i get the cross chain in 39 ring with either 24, 28 or 32 cogs. When these combos worked fine with the old RD. could the longer cage in itself create this problem.

This is an outside chance, but on these RD’s it’s easy to thread the chain on the wrong side of the little nub on the pulley cage between the jockeys. Noise galore

You didnt mention if it was new. Just wondering if the pulleys were off and maybe reversed when put back on.

Bracket axle unit installed in the horizontal position as it should be?

I've seen people incorrectly attach it in a vertical position, they had problems with shifting and chain tension.

https://cimg7.ibsrv.net/gimg/bikefor...625b6ddaa0.jpg


Is there a gap between the stoppers on the bracket axle unit and the derailleur hanger?

https://cimg7.ibsrv.net/gimg/bikefor...1d41fcacd1.png

Yeah that seems strange and not what I would expect.

The chain tensioning is much higher with the Shadow derailleurs because of the stronger springs (designed to keep chains in place). I've found that this makes "misalignment" of the chain (cross-chainging) a noisier affair. When the chain is more or less inline between front and rear sprockets, it runs fine. But when you start getting outside that "straight and narrow", it's less tolerant of that. And it makes intuitive sense -- the derailleur cage is pulling harder on the chain with Shadow derailleurs compared with traditional designs.

I've tried to make my RD-M3000 derailleur work correctly on a number of bikes, and I just couldn't find satisfaction with it. I've posted a few questions about these derailleurs here in the past. Here is a thread. Here is a second one. Neither is directly the same issue as yours, @Bingod, but I believe the behaviors may be related.

Thanks for this. This is the conclusion I'm coming to and have now read elsewhere how people have struggled with this mech. Too bad. Ill keep it on until i become too fed up with it.

Yes thanks, mine is set up correctly. It took a bit of head scratching to initially figure that out as there were no detailed instructions included

FWIW I've been having problems with my XT 9 speed as well.
My Jamis Aurora Elite (2010) came with a triple 9 speed setup, Tiagra (4503) up front (50-39-30) and XT in the rear (11-34) with a M771 RD. I bought it used and it needed a new chain and cassette, which I promptly replaced. However, I was still having issues smoothly shifting through the entire range of gears and paid a local shop to align my derailleur hanger, thinking that was the issue. Still no joy. Also had a lot of chain slop in the smaller cassette rings.

I found a like new takeoff of the "upgraded" M772 shadow RD. Installing this alleviated some of the chain slop I was getting in the smaller cassette gears but exacerbated my issues shifting throughout the entire range of the cassette. If i indexed the drive train to behave well on the large cassette rings, it would rub on the small ones and vice versa. Took it to a local shop and they thought my derailleur cage was slightly bent, and they 'fixed' it. Still didn't quite ride right.

Well, I figured, if it was slightly bent it would never be perfect. So I bought a brand new Deore (not XT) M592 RD, which is essentially the same as the M772 but more or less commonly available. Still having the same problems - I can index and shift well great through 2/3 of the cassette but then the last couple gears either start slipping or fail to shift at all. Turning the barrel adjusters just moves the problem to the other end of the cassette. A funny thing happens in the 8th cassette cog where the chain sits up on the edges of the chain instead of slotting into the grooves.

Nothing looks bent, everything adjusted per Park Tool video recommendations, all shift cables and housings and cable guides replaced with new components, shift controls oiled. Can't figure it out other than thinking something on the frame may still be tweaked.

I just ride my bike like it's a 6 speed =/

Do you have any other derailleurs to try? You can get an RD-M360, or any 7/8/9-speed derailleur, pretty inexpensively and swap it to see if you have the same behaviors, or if you can tune it out with a traditional design. The biggest challenge with swapping back and forth between a Shadow and a traditional design is the length of the cable housing and cable. The Shadow has a much more direct (and, thus, shorter) cable routing.

For me and my bikes, I ride triples with front derailleurs, so I'm not so concerned with chain drops the Shadow legitimately helps to avoid. I just have a cheap $10 Lizardskin stay protector to keep everything clean and quiet.

Yeah, per my lengthy narrative I started with a M771, tried a M772, and now have a M592. I have not yet gone back to the M771 to see how that fairs now that I replaced all the shift cables and housings.

My commiserations, I experienced all of that too, Right now I have it set so I can shift all through the cassette but it gets noisy in the 3 largest cogs and I accept that I will occasionally miss a shift in the smallest cogs. I dread putting my gravel wheels back on and potentially beginning the process all over again. I do now make sure the wheel is perfectly set in the dropouts and my QR is cranked tight, just to avoid any chance of misalignment or movement there.

Yes, having to cut the cable and housing has made me fiddle longer than I would have otherwise. I do believe the chain dropping is slightly improved, though I do hold my breath when I'm riding in the biggest cog and I need to downshift to the 26T ring. Typically I shift up a gear on the cassette beforehand. This is only a problem if I'm riding on a steep gravel/dirt trail that I'm not too familiar with, or my mind is distracted by the scenery or just wandering and I need to downshift in a hurry. So quite often as it happens.

I thought that the problem is that there is a different cable pull lengths between the mountain shifters and road shifters. Even though the shifters are both 9 speed, they are not compatible.

I use the M771 derailleur with my 10 speed 105 shifters on a 10 speed setup.

I'm pretty sure road and mountain are interchangeable on 8- and 9-speed drivetrains. Supporting info:

https://www.bikeradar.com/advice/buy...r-derailleurs/

There are a few exceptions (like Tiagra 4700 and old Dura-Ace), but I don't think those are in play in this situation. That said, that article concludes the Shimano section by saying:

sorry i missed your post. The RD was new in box

Good call. I made that mistake when initially threading the chain through the RD, but I corrected it, but only after i had reconnected the chain.