A few hours of riding often isn't enough to get a solid first impression of a bike part, let alone an entire component group. But in the case of SRAM's new X0 10-speed 'family', those few hours comprised 2,300ft (700m) of climbing and a whopping 20,000ft (6,100m) of descending on the awesomely fast, technical and demanding trails around the Super D course in Ashland, Oregon – and even racing the event for ourselves.
Time will yield more information on X0's long-term durability but after our unusually condensed test session, we're comfortable declaring X0 as a harder hitting version of SRAM's flagship XX group, offering nearly identical levels of performance but with more tactile feedback, just a bit more weight, and much lower replacement part costs when the inevitable happens.
Shifting – 10 speeds but the same familiar X0 feel
Current X0 trigger users should find the new 10-speed pods feel just like home despite the extra rear sprocket, changes to the cable pull ratios and heavily revised rear derailleur geometry.
Compared to the lighter-feeling XX, X0's trigger shifters boast higher lever efforts and stronger and more tactile clicks consistent with the current generation. Especially in technically demanding areas with lots of drops and jumps, or high-speed situations with lots of vibration – say, for example, braking bumps at the Ashland Super D where our top speed was nearly 40mph (65km/h) – this provides reassuring feedback, without feeling too heavy.
Chain management in rough terrain is also better than on XX, with what feels like a stiffer cage return spring. Rear shift quality is little changed from nine-speed X0, with precise and reliable chain movement from cog to cog. The tighter 10-speed spacing does require a slightly finer adjustment, though, so cable tension adjustments are a tad more finicky than before.
The X0 shifter retains the previous generation's sleek shape and adjustable pull lever
Front shift performance on our 2x10 configuration is a massive improvement over previous SRAM drivetrains and now wholly in line with XX, with the same X-Glide tooth alignment technology and heavily shaped and ramped surfaces. Chain movement from ring to ring – even under power – is uncannily smooth and direct, and noticeably better than SRAM's road groups.
Aiding matters on our test bike was the two-ring setup and dedicated front derailleur – which we should mention is far more svelte and lighter than previous non-XX off-road versions. Both the derailleur cage and thick, machined chainrings are notably stiff, making for fast and forceful shifts – though we didn't have to shift up front as often as usual on account of the versatile 36T cog on the rear cassette.
SRAM's trick X-Glide front shift technology includes over a dozen points where the chain can mesh perfectly between both chainrings for far smoother upshifts and downshifts
Braking – plenty of power and modulation plus top-notch ergonomics
The Avid X0 hydraulic disc brakes are close cousins to last year's Elixir CR Mag units but with all-aluminium forgings instead of the predecessor's magnesium pieces. Avid product manager Paul Kantor says system weight remains unchanged at 333g (front, post mount, 160mm rotor), and so is performance, with excellent power and control to go along with the superbly adjustable ergonomics and lever geometry.
Minor tweaks include a detented pad adjustment to prevent setting migration and a new easier-to-replace main pivot that doesn't require major lever disassembly to replace one that's worn out. Kantor says part tolerances have been tightened, too, which should yield better long-term reliability and more consistent factory bleeds.
Avid's X0 calliper is based on last year's Elixir CR Mag. Forged aluminium replaces magnesium
Drivetrain – new crankset configurations and cassettes
The new Truvativ X0 crank features carbon fibre arms with separate bolt-on alloy spiders instead of a one-piece construction as with XX. According to SRAM's Chris Hilton, the two-piece configuration makes for a lighter, stronger and cheaper end product than would normally be possible with an all-carbon bit at this price point.
In contrast to previous SRAM carbon crankarms – even XX – the new X0 arms have no full-length aluminium spine. Instead, the company's new 'Threshold' technology uses an internal non-structural foam core and separate aluminium lugs at the bottom bracket and pedal ends that are all co-moulded together.
The new SRAM X0 cranks have a hollow foam core construction
Despite the multi-piece arm construction, Hilton says in-house mechanical testing shows yield failure in the axle, not the arm – meaning that if and when the system is overloaded (say, during an exceptionally bad landing), the axle will bend or twist but the arms will remain intact. As evidence of the durability, he says sponsored downhill riders will be racing on X0 carbon arms later this year.
The bolt-on spiders will allow for some interchangeability with drivetrain configurations. SRAM are still debating whether or not to offer the spiders on their own to consumers but it remains a possibility along with a dedicated singlespeed option. Either way, consumer versions will all be offered in a single 166mm Q measurement instead of XX's additional narrower 156mm option.
The new X0 crank is built with carbon fibre arms and a separate, bolted-on alloy spider
X0 will have more gearing options, though, with the same 26/39T and 28/42T sizes as XX but also a three-ring setup, a smaller 24/36T range aimed at 29ers, and even possibly a dedicated singlespeed spider further down the road. Three-ring cranks will feature the same X-Glide technology as the two-ring ones, with unique 22/33/44T sizes in keeping with the system's required fixed-integer ratios across the spread. If it's even remotely close to the performance of the two-ring setups, we expect the three-ring shifts to be simply superb.
Bottom brackets now incorporate Truvativ's new Gutter sealing system almost across the board, which is said to be far more adept at dealing with water. Stock non-ceramic bottom brackets are noticeably freer spinning than before straight out of the box on account of the lower-friction materials, reduced swept areas and slightly more loosely pressed-in bearings (they're now secured in the cups with snap rings).
Truvativ have incorporated a new 'Gutter' seal design into nearly all of their bottom brackets
Truvativ will offer the bottom brackets in a multitude of versions, including standard GXP, PressFit GXP and PressFit 30, dedicated adapter cups for Specialized frames, Trek's BB95 drop-in system and standard BB30. While we did plenty of wet riding in Ashland, it wasn't quite enough to see how well the system will hold up over time. Stay tuned for more once we finish a more rigorous long-term test later this summer.
What we did notice, however, was the quiet running of the drivetrain, what with the more heavily chamfered PC-1091 chain and rounded tooth edges of the PG-1070 cassette's stamped steel cogs. PG-1070 is actually intended for the X9 family but the appropriate XG-1080 cassettes weren't quite ready in time. We can't wait until they are, though, as they should deliver nearly the same benefits as XX but at a much lower price point – US$200 compared to about $350.
We ran a quiet running and smooth shifting semi-spidered SRAM PG-1070 cassette
XG-1080 is essentially still a hollow dome in form but instead of being machined from a single hunk of chromoly, each individual stamped steel cog is press-fitted to its neighbours around its entire circumference with a number of high-strength steel pins (dubbed 'PinDome' for now). As before, the innermost cog is a thick aluminium plate that also transfers load to the freehub body.
The end product is nearly as light as XX but cheaper to manufacture, quieter running on account of the stamped cogs' more rounded edges, and has even better mud pass-through than XX. Assuming it comes through as promised this August, we expect it to be the go-to replacement even for XX owners who put in a lot of hours and don't want to spend quite as much on expendables.
Our fork of choice for the Ashland Super D was RockShox's new Revelation XX World Cup
X0 = XX for the rest of us
We'll continue to test the new X0 family over the coming months but initial impressions are highly favourable. Though not quite as light as XX, it's far more versatile, with expected appeal across nearly every off-road category as with the current X0 components. Adding to that broad reach are the multiple drivetrain configuration options, three available cage lengths for the rear derailleur, countless front derailleur options, rotor sizes from 160-203mm, and even four colour schemes.
There's an X0 setup for nearly any mountain bike configuration. Cross-country and trail riders who still demand – and can afford – SRAM's absolute lightest will want to stick with XX but for the rest of us, X0 is clearly the way to go. We're still waiting on official pricing from SRAM and will update this article once we receive it but official weights are as follows:
- SRAM X0 10-speed rear derailleur: 190g (short cage)
- SRAM X0 10-speed front derailleur: 130g (2x10)
- SRAM X0 10-speed trigger shifters: 232g/pair (2x10)
- Truvativ X0 10-speed crank: 788g (42/28T, GXP), 739g (42/28T, BB30), 782g (22/33/44T, GXP), 728g (22/33/44T, BB30)
- Truvativ GXP Team bottom bracket: 107g
- Avid X0 brakes: 333g (front, post mount, 160mm)
- SRAM XG-1080 cassette: 260g (11-36T)
- SRAM PC 1090 chain: 257g (114 links)