BH

G5

In its debut Tour de France, AG2R's Rinaldo Nocentini rode the BH G5 into the yellow jersey on that Tour's longest stage and highest finish, at Andorra Arcalis. He held the jersey through the next two Pyrenean stages, over the massive Col de Tourmalet, and through a handful of nervous transitional stages across the heart of France. The significance of this is that his ride to the top of the classification exemplifies the qualities of the G5 - long distance comfort, light weight, and sharp handling.

BH built the G5 upon the foundation set by the G4, a bike legendary among climbing specialists. What was already a groundbreaking frame design, with its extended seat mast, the G4 was improved upon by careful examination of the carbon lay-up. Chris Cocalis, the man who brought you Titus and, more recently, Pivot Cycles, is the driving force behind BH USA. He is known for his nearly fanatical obsession with testing, and his engineering team strived to tune the ride and to optimize the lay-up of the existing bike. The result is the G5, a frameset that delivers twice the stiffness in the bottom bracket area and a 170% improvement in stiffness in the head tube. Amazingly, these improvements came without any increase in weight.

The G5 frame and fork are constructed as monocoques. That is to say that they're each built as one structural unit, with the composite material laid into a mold and formed in one piece. This process ensures uniformity in the lay-up, but it also allows their designers the freedom to create complex tube shapes, such as the down tube on the G5. It's one of the most striking details of the bike. What you'll notice is a channel on the underside. Aesthetically it serves to hide the cables from view, and for this clean look you won't suffer the added few grams regularly associated with internal routing. In addition, the channel adds stiffness to the down tube, and BH includes an extra set of threaded mounts for a no-fuss mounting option for your Di2 battery.

The G5 is also notable because its 100% carbon construction excludes any alloy bits whatsoever. To remove metal in certain areas of the bike frame required extensive engineering and design. The rear dropouts are a great example. Typical construction might use alloy dropouts, bonded-in after the composite layup has cured. The BH full carbon dropouts are formed along with the rest of the frame, and this process assures continuity in the material. The result is a more durable structure. And when you're looking at a frame that weighs significantly less than the lightweight wheels you'll hang on it, it's reassuring to know how strong it is when you're in an all-out sprint or attacking the group over a steep climb. This all-carbon method also eliminates the need to use alloy for the cups in the head tube and for the crown race seat on the fork. The molded-in carbon cable guides and braze-on front derailleur tab are also integral parts of the structure. Lastly, the Pressfit 30 bottom bracket is carbon fiber, the nature of the nylon sleeved Pressfit bottom bracket eliminating the need for additional alloy cups there as well. This effort towards a homogenous structure allows the G5 to be as light as possible without sacrificing strength or stiffness in the least.

As you look at the G5, you'll see that BH sticks with a time-proven and simple frame layout. Aside from the channeled down tube, the rest of the tubes don't stray too far from the norm. The top tube morphs from a rounded shape at the head tube junction to a soft triangle near the intersection with the aero-shaped seat tube. While not intended to compete with the likes of the latest crop of aero road bikes, the G5, with this subtle aero shaping and rear wheel cut-out on the seat tube, minimizes some drag at speed without treating you with the usual harshness over coarse road surfaces that you'd experience with aero frames bearing frame tubes with a long chord length.

Cocalis was adamant that the G5 be the benchmark for torsional stiffness in the seat tube and the head tube area. As stated before, the careful optimization of the number and orientation of the high modulus carbon fibers add stiffness and strength. This goes hand-in-hand with the oversized 1.5" tapered head tube and bottom bracket area. The chainstays follow a similar design path. Their massive vertical section resists even the most brutal efforts against the pedals.

The seatstays are a different story. Here, BH intends some deflection to ensure comfort. From the side, they are pencil thin and bear a slight curvature to act, in a limited fashion, like leaf springs. When you ride the G5, you'll notice that they work to absorb vibrations from broken road surfaces. Over the course of a long ride, you'll appreciate the added comfort. The seatmast follows suit. While the lateral stiffness has been increased over that of the G4, it's designed to be forgiving in the vertical plane, working in concert with the seatstays. The seatmast uses an abbreviated post that offers more adjustment than the typical mast topper.

The BH G5 is available in Blue, Green, and Red. It comes in five sizes from X-Small to X-Large. The frameset includes a full-carbon fork with a 1-1/8 - 1.5in tapered carbon steerer. The integrated headset bearings are also included along with the abbreviated seatpost. You'll need a braze-on front derailleur to complete the bike build.