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X0 Rear Derailleur
The X0 rear derailleur is available in three cage lengths, short, medium and long (tested), and comes in Silver, and Black, Blue, Red and Gold graphic colors, and retails for $255. The inner pulley cage is made from aluminum while the outer is a carbon fiber composite, and the parallelogram linkages are forged aluminum with wide pivots to ensure linkage stability and stiffness. It has sealed bearing pulleys, and utilizes their Exact Actuation Ratio technology, which is a 1:1 actuation ratio (shifter cable travel : derailleur movement), and the EA offered simple, stable and easy shifting, regardless of the load applied, the cog set spacing and cable tension. Cable routing into the derailleur uses their Direct Route Technology, in which it connects directly to the actuation mechanism to lessen damage and decrease friction and input effort. I have always liked the 1:1 actuation ratio of SRAM’s rear derailleur’s, and the X0 rear offered crisp shifts that had a nice detent, without any ghost movements or over shifting. Rolling up or down the cassette worked just fine, and with the aid of the Grip Shift, you could do large swaths of gears at once. With the big 11-36 range of 10 speeds on the cassette, it took a bit of tweaking of the high and low limit screws to get all the gears rolling properly, and the longer cable meant occasional adjustments were needed to keep things sharp and slop free. The rear has been pretty durable, and has taken a lot of abuse, slamming and scrapping past rock squeezes and ledges, and the only thing it has suffered is some cosmetic scratches along the outside edge. The spring tension has stayed taut, so shifting has been crisp, and the cage pulleys have continued to roll with low friction, and the parallelogram pivot points have retained smooth movement and actuation.
PowerChain 1091R Chain
The PowerChain 1091R is made from Nickel silver with Chrome hardened pins and hollow rivets, and retails for $65. It uses the highly functional PowerLock tool-less connecting link, which always makes installing and removing a chain much easier. When the chain was new, it shifted without any issues even when I forgot to lube it, but after eight months of heavy abuse, and I’m getting some ghost shifts. I tend to be a low gear granny monster, wreaking havoc and creating huge amounts of torque, and the chain hasn’t failed or died prematurely.
Truvativ X0 Cranks
The Truvativ X0 cranks are available in 2X10 version with 22-36, 24-38 (tested), 26-39 and 28-42 gearing options, and PF30, BB30, GXP and GXP PF bottom bracket configurations (not included). They come in Silver, and Black, Blue, Red and Gold graphic colors, 170 and 175 lengths, and retail from $444 – $513. The three-piece Truvativ X0 cranks are comprised of the drive side arm with attached spindle, non drive side arm and bolt-on chainring spider. The crank arms are hollow carbon fiber composite with a non-structural foam core and aluminum inserts at the bottom bracket and pedal which are co-molded in place. The forged aluminum spider meshes onto a spline on the inside on the non-drive side arm, and in this tested version, it is comprised of a 24 tooth chainring, 38 chainring and a bashguard. The chainrings are made from CNC 7075 aluminum, and the bashguard is carbon fiber. With this 24-38 gearing and the optional 22-36 version, the odd spacing is 104/64 BCD, which is required to fit everything within the confines of the system.
The Truvativ X0 cranks have a minute amount of flex if you stand on the arms during a technical move, and it feels like the spindle twists, and not the arms directly, but I never felt any loss of power when cranking away while pedaling. The arms are stiff, and have been durable, with only the typical cosmetic shoe rub on the outside. The pedal inserts haven’t loosened, which can be a culprit on carbon fiber and aluminum glue-in interfaces. The ends of the carbon arms can get chipped slightly if you hit lots of rocks (like I do), so I added some crank arm boot protectors.
The 24-38 chainrings nicely meshed with the 11-36 cassette, especially if you ride a 29er, or you’re a granny gear aficionado. Their X-Glide technology functions well, and the synergy of aligning the chainring pick-up rivets to the chain pivot pin gives smoother shifts on any terrain or power mode. The closely spaced engagement zones around the circumstance of the rings, gives faster shifts under any load, though I found it somewhat clunky during the transitions and not as smooth as Shimano. On occasion, the transition of the 24 to the 38 could be temperamental, and I think a closer ratio, such as 24-36 would be beneficial. They have options for other gearing ratios, including 26-39 and 28-42, and the already mentioned micro gearing of 22-36 and 24-38.
The 38×11 (chainring/cassette) gearing isn’t the most functional when you want to press the bike to Mach 1, but it will get you going at a decent clip, and this set up is meant for AM and AT riding, not full on XC racing. The 38T offers good obstacle clearance and the 24T granny keeps the gear inches low (gear ratio x wheel size), which is especially nice for 27.5″ and 29″. After about eight months the 24T granny is worn out, and shifts aren’t quite as crystal clear like they were when new, but small chainrings get an extreme amount of torque placed on themselves, so it exasperates the wearing. They don’t yet sell individual chainrings, so you’ll need to buy the entire spider to replace anything, and even though $140 seems expensive, you do get two fresh chainrings and a bashguard in one complete package.
The bashguard has gotten some heavy abuse, and is showing some fraying and shredding of the carbon fiber material. It is only happening at two locations, right smack opposite the spindle when the crank arms are parallel to the ground. I think a more robust thickness might help with the longevity, but at least it prevented damage to the large chainring.
The bottom bracket includes Truvativ’s new Gutter sealing system, which has a better seal design, with less drag, greatly improved water resistance and bearing durability. It has been durable and smooth rolling throughout it usage, without any grittiness or stiction, and the cranks easily spun through them.