ORBEA OCCAM 29 HYDRO

The Orbea Occam 29 Hydro represents yet another enthusiastic step for Orbea into the realm of dirt. Like its acclaimed predecessor, the 26-inch Occam, the Occam 29 Hydro provides a comfortable, active ride that befits marathon racing. And, like its sibling, the all-new Occam 29 Carbon, it incorporates the fast-rolling, trail-slaying advantages of 29-inch wheels. However, it's made of hydroformed aluminum, so it does all this at a price that will not annihilate your budget.

Despite several design parallels, the Occam 29 Hydro is not simply the 26-inch Occam, tweaked -- it was developed as an all-new platform using Orbea's Advanced Dynamics technology. From the earliest stages of design, Orbea analyzed the Occam 29 Hydro's performance in a computer simulation with virtual riders on board. Why is this so important? The variable and dynamic forces exerted onto a mountain bike by the rider are an integral part of how the bike accelerates, stops, and tracks over bumps, so it makes sense that Orbea considered these forces in their design process from the get-go. Of course, when a prototype was ready, Orbea replaced their virtual riders with real ones for exhaustive on-trail testing.

It's unfortunate that in some mountain biking circles, the phrase 'single-pivot' has become synonymous with 'unrefined' or even 'archaic.' This is nonsense. Single-pivot suspension designs such as the one found on the Occam 29 Hydro are still relevant, and often preferred, for good reason. When designed well, they're bombproof, lively, predictable, and -- when mated with a good shock -- easy to set up and tune. The Occam 29 Hydro's main pivot is located on the seat tube, above the bottom bracket. This neutral location strikes a superb balance between pedaling efficiency for climbs and sprints, and plushness for freewheeling descents. A 2013 Fox Float RP23 shock performs the squishing duties and yields 105mm of smooth rear-wheel travel.  Adding to the Occam 29 Hydro's theme of sophisticated simplicity, this shock has a new CTD (climb, trail, descend) damper that makes adapting your tune to the terrain as easy as flicking a switch.

One oft-lamented characteristic of single-pivot full-suspension bikes is brake squat, the suspension compression that occurs when you grab a handful of rear brake. This brake-induced compression is often felt by the rider as stiffening of the rear suspension. It's important to point out that nearly all modern full-suspension designs, including much-hyped linkage designs, squat while braking. However, single-pivot designs have a reputation for squatting/stiffening more, and to some riders, this is an undesirable trait.

To resist brake squat, the Occam 29 Hydro incorporates a concentric pivot at the rear axle. As a result, the brake caliper is not wholly beholden to follow the arching path of the chainstays, which form the main levers of the swingarm, as the suspension cycles. That freedom of movement results in more active suspension under braking, producing a ride quality similar to that of a more complex four-bar suspension system, or a single-pivot bike with an aftermarket brake floater.  End result? With the rear brake on, the bike will stutter less over bumps and have improved traction.

When looking at a 29er's geometry, two measurements we always examine closely are head tube angle and chainstay length, and we like what we see with the Occam 29 Carbon. At 17.5 inches, the chainstays are sufficiently short to allow for nimble traverses in switchbacks. We also feel that the 70-degree head tube angle (with a 100mm fork) is spot-on, because it creates stability, but allows for the kind of minute steering corrections that are sometimes required to keep  momentum-carrying 29-inch wheels on line.

Orbea designed in clean cable routing by running the rear brake and rear derailleur housing along the top of the downtube, secured by bolt-on guides. The front derailleur cable is internally routed through the frame to shelter it from contaminating muck. The Orbea Occam 29 Hydro has a 1-1/8 to 1-1/2 inch tapered head tube, and you can run a 100mm or 120mm front fork. The rear dropout accepts either a 142 x 12mm thru-axle or a standard QR. The brake tabs are the post-mount style. You'll need to pair the frame with a 31.6mm seatpost and a 34.9mm high clamp/bottom pull front derailleur. The Occam 29 Hydro comes in sizes Small through Large. All Orbea frames have a lifetime warranty against manufacturing defect.

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