Menu

A Detailed Look at SRAM’s X0 Hubs

Lighter Than Air and Louder Than...

Words by Morgan Taylor. Photos by Morgan Taylor.
January 6th, 2014

SRAM’s light weight and no-nonsense 2014 X0 hubs take dead aim at the aftermarket. While the XX1 drivetrain and some slick complete wheelsets have taken the spotlight for the past year and a half in the mid-travel drivetrain world, let’s not forget that the X0 level of SRAM componentry was previously considered the top choice for all but the weight-weenie-est riders. It may actually come as a surprise to hear that this year is the first time the X0 name has graced a hub, with X9 hubs seeing spec in the OEM market as well as the cabinets at your local bike shop.

There is a certain level of refinement necessary for SRAM to claim they’ve finally produced “a hub worthy of the X0 name”. The X0 hubs sport four large pawls, 6-bolt rotor mounts, use j-bend spokes, and are available in 28 and 32 hole drilling – all points that will be music to the traditionalist’s ears. Yet they tip the scales at a very scant 130 grams up front and 250 in the back – that’s 55 and 35 grams lighter respectively than Hope’s Pro2 EVO hubs – which sets the stage for some very light wheelsets even with the extra spokes over many complete wheel options (including SRAM’s own wheelsets which are all 24 spoke front and rear).

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

Our set of X0 hubs has been laced to Stans Flow EX 29er rims, which are a burl-over-weight 550 grams each, and hooked up to a X01 1×11 groupset.

52 Points of Engagement

Using four large pawls each with its own spring, the X0 freehub body is a simple design that is also easy to clean and service. With 26 teeth in the hub shell, opposing pairs of pawls drive the hub, realizing a 52 point or 6.9º engagement. Two big pawls slapping into the hub shell 52 times a rotation does result in quite a loud hub – a point which has both its ups and its downs. Packing some more grease in there will quiet things down a bit, but these hubs will always be heard.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

The X0′s four pawls, which engage the hub shell in opposing pairs.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

The freehub bearings sit on raised sections of the axle, with the entire unit removeable by hand.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

26 teeth, four pawls utilized in pairs, 52 points of engagement.

The XD Driver Body and Cassette Interface

SRAM’s 11-speed cassettes are only compatible with XD driver bodies. Fortunately they made this technology available to be licensed by other hub makers, and the list of manufacturers doing this is constantly increasing. This new design is a shape we’re seeing fairly often; let’s have a look at how that new interface actually lines up with the cassette.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

The cog interface is the same shape as a 10-speed freehub, but only the 42 tooth big cog actually engages the freehub body.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

The 42 tooth cog is made of super thick aluminum while the rest of the cassette is machined from a single piece. The whole business bolts on using a standard cassette tool that screws the threads seen here on to the driver body.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

Putting the threads on the inside is what allows the use of a 10 tooth small cog. Note the exposed cartridge bearing at the outboard edge of the XD driver body.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

In there by the notches for the cassette tool you can see a small step. This lines up with the aforementioned exposed bearing to allow the outboard edge of the cogset to ride right on the freehub bearing.

The Details

The design of the hubs is right in line with the clean design of the rest of the X0 group. Just a small splash of red and white on the otherwise matte black finish.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

Keeping with the simple theme, the end caps are removeable by hand and both the same size – but the XD driver’s 10 tooth compatibility requries a slightly smaller diameter drive side end cap. Of course, you can get a standard 8-9-10 compatible freehub body as well.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

Using traditional j-bend spokes ensures easy replacement no matter what your local shop situation.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

6-bolt ISO rotor mount to ensure compatibility with any brand of brake.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

Pulling the end caps reveals a large cartridge bearing. The X0 hubs can be fitted to 12×142, 12×135, and 135×10 standards.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

The 130 gram front hub is expectedly simple looking.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

Again, j-bend spokes, in our case 32 of them – this is a stiff wheelset.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

The front end caps are the same on both sides; caps are available for 15mm, 20mm, and QR axles.

sram-xo-hubs-16

That same simple disc mount.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

And another big bearing riding on the axle that can accommodate 20mm forks.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

Clean graphics to match the X0 group.

sram, hub, hubs, xo, x0, x01, xx1, x9, hope, pro2, stans, weight, price, cost

More on that X01 group shortly…

With a simple, non-proprietary design, lots of engagement, and super light weight, SRAM’s X0 hubs are a sweet aftermarket option. At $197 for the front and $364 for the rear, they ain’t cheap – but what’s 90 grams worth to you, weight weenie?


So, what is 90 grams worth?

  • balfaboy

    I find it odd that they are using diffrent free hubs in there wheelsets vs their stand alone hubs. Intrested to see how they hold up in the wet winter here in BC

    • boomforeal

      ja, interested to see how that cartridge bearing stands up. despite the end cap its pretty exposed. are different companies developing their own xd drivers, or just integrating sram’s on to their hub bodies?

    • morgman

      All XD drivers look the same from the outside, with the exposed bearing. Lots of people with lots of mileage on XX1 by now, should be able to see if that bearing has been causing any issues. Poll the audience?

  • mattthemuppet

    I don’t really understand how two pawls engaging a 26 tooth ring at the same time can result in 52 points of engagement? 2 opposing pawls = 1/2 the force per pawl vs. a single engaged pawl, but it doesn’t double the number of engagement points in any way that I can see. Or are the 2 pairs 1/2 a tooth of engagement out of phase? That would make more sense. Sorry, just rambling..

    • morgman

      Your second guess is right. Two pair of pawls engaging half a click apart.