BH uses a variety of construction methods to craft its carbon frames.
The Speedrom uses monocoque construction to create its sub-1000 gram frame. This technique is used by the majority of the industry. Workers hand-lay carbon that has been pre-impregnated with resin in specific patterns and thicknesses over a nylon or latex bladder. The pre-preg carbon is then inserted into a mold that is heated up to high temperatures to melt the resin. The bladder is inflated to incredibly high pressure to drive out any air in the material and push the carbon to its final shape. After cooling, the seatstays and chainstays are bonded to the front triangle.
Tube to Tube construction is very different from Monocoque. It allows much more flexible manufacturing and very low frame weights. In this method, each tube is made individually to exacting standards. The tubes are then mitered like you would miter an alloy tube for a bicycle. Glue is applied to the ends of the mitered tubes, and the frame is then pre-assembled in its final geometry. The frame is then reinforced by wrapping carbon around all the joints. After the finished frame is cured, the result is a very light, sub-900 gram Connect.
The G5 uses the most sophisticated and advanced materials and manufacturing techniques known to bicycle builders. It also has complex tube shapes and geometry to achieve a weight and ride quality that are unequaled. While it uses monocoque construction, there is nothing ordinary about this bike. Its 850 gram weight and sublime ride quality are proof.