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
Last edited by Bingod; 09-19-19 at 10:15 AM.