BH claims the down tube channel dramatically increases rigidity while also partially concealing the derailleur cables for a cleaner look. An integrated battery mount for Shimano Dura-Ace Di2 is included down by the bottom bracket, too.
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G5 ready for Saturday's Tour start
AG2R will replace its BH G4 carbon road bikes with a new G5 model that the team hopes will carry its riders to some success in this year's Tour de France. According to BH, the new frame is substantially lighter – claimed weight is just 810g in a 54cm size – but also more rigid by as much as 100 percent at both the bottom bracket and in front triangle torsion.
Stiffness increases come courtesy of larger tubing diameters nearly across the board, a newly tapered 1 1/8"-to-1 1/2" front end, and a rounded rectangular down tube that features a stiffening channel down the full length of its underside. That channel also helps conceal the derailleur cables for a cleaner look and there's also an integrated mount down by the bottom bracket for a Shimano Dura-Ace Di2 battery. Up front, the matching all-carbon fork – made by Edge Composites – includes a correspondingly oversized crown for improved braking performance and carbon dropouts.
BH has also maintain the oversized theme down at the bottom bracket with the inclusion of the increasingly popular BB30 system. Though AG2R will undoubtedly use BB30-compatible cranks from team sponsor FSA, BH will also offer to consumers press-fit adapter cups with built-in bearings for Shimano cranks – or presumably any other crankset that uses a 22mm-diameter spindle and identical bearing spacing. Seat stays, on the other hand, have actually gone down in size and adopt a slight curve to add a modicum of comfort over rough roads.
The G5 retains the G4's deep-section cutout seat tube and semi-integrated seatmast design but matches it with a new, easier-to-use two-bolt seatpost 'stub'. This setup provides the sleek look and stiffer pedaling platform of a fully integrated deep-section setup but doesn't need to be cut to the length. Moreover, assuming the profile of the tube hasn't changed, consumers might also be able to run the G5 as a fully integrated system with a clamp-on head if so desired.
Save for the BB30 sleeve inserts, virtually everything on the G5 is now carbon, including the slotted housing stops, rear dropouts, integrated headset bearing seats, and the front derailleur braze-on tab. That tab is further reinforced with additional carbon 'webs' at both top and bottom, thus presumably improving front shift performance especially when used with the Di2 changer. Similarly, the replaceable rear derailleur hanger has been beefed up to provide a stouter platform for rear derailleurs – a common request from top-level teams.
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