X.0 isThe best 9sp rear derailleur available from SRAM. Whether your game is XC race or extreme freeride, youll appreciate its high-end features like a weight-saving carbon fiber outer cage andTitanium main spring. Works with SRAM ESP 1:1 ratio shifters only sealed bearings claimed weight 203 grams
Strengths: Strong, reliable, set & forget, maintenance free, damn sexy. Mine's 5+ years old and shifts like new.
Weaknesses: None really...
At some point MTBR have, for some unknown reason, amalgamated the 9 & 10 speed X0 rear derailleur reviews. Anyway, reading through the combined 9 & 10 speed reviews, a lot of people are complaining that this derailleur is weak, that the carbon cage snaps. For example; "A stick got caught-up in my back wheel, snapped several spokes, ripped the rear wheel apart, and sucked the rear derailleur into the wheel, where it was destroyed. This derailleur sucks." The rear wheel gets shredded and you think the derailleur's the weak point? No derailleur is designed to withstand carnage like that, what the hell were you expecting? I've said it before and I'll say it again, there are a lot of stupid people on these forums.
I originally had this derailleur on a Heckler, where it served me perfectly for several years. I eventually thrashed the Heckler frame out, replaced it with a Foes FXR 2:1, and swapped the X0 rear derailleur to the new bike. No problems at all, the derailleur easily outlasted the frame. This would be completely unthinkable with a Shimano derailleur, you'd be lucky to get a couple of seasons out of it before it crapped itself and died. My X0 about 5 years old and although it looks beat-up, it still shifts like new, ie. perfectly. Once or twice a year I'll take the bike to my lbs where the mechanic will adjust the shifters/derailleurs, and it's set for another season of full-on, AM abuse. It's this kind of set & forget reliability that's sorely missing from Shimano's offerings. I've been riding mtb for about 20 years, and grew up with LX, XT, and XTR. It was a constant battle to keep the derailleurs shifting accurately and reliably, I was always hassling people to tune my derailleur for me. With Shimano, checking to see if your XT derailleur was shifting properly would be an essential prerequisite to any ride, much like checking the air pressure in your suspension these days. Having to shift down mid way through a steep section meant living with that dreaded mechanical crunching of gears. I admit the XTR trigger action feels smoother (SRAM feels rather clunky), but SRAM's 1:1 action ratio just works so much better, is far more accurate and reliable, and less susceptible to cable stretch and dirty lines. The X0 rear derailleur is vastly superior to any Shimano derailleur I've ever had, though I admit I haven't owned the new XT, Saint, or XTR. Nor do I intend to try them, I'll be sticking with SRAM until I have reason to do otherwise.
a Cross Country Rider
from Orlando, FL, US
Weaknesses: hex bolt that attaches it to the derailleur hanger seems a bit weak as the head of it is somewhat stripped
This is by far the nicest derailleur I have ever owned. It came on a my Giant that I got on Craigslist for a REALLY good deal. It works great. It shifts smoothly, precisely, and quickly when adjusted properly. It shifts how I want it to when I want it to, nuff said. I hardly ever seem to have trouble with it throwing a chain or misshifting, unless I really take a hard hit. If you can dish out the cash (or luck out and get it on a bike as an added bonus like me) I would say definitely get it. You should not be disappointed. It shifts like a dream. I give it 4 chilis for value because it seems overly expensive, although, I guess it is worth it.