Well color me impressed, right as the dust settled on Boost 148 hub spacing, a new wave of trail bikes are sporting 157 mm DH-hub spacing under the moniker of Superboost Plus or SB+. Packaging the crank arms, chainring, tire, and chainstay has always been a challenge for frame designers, and SB+ offers some clear advantages with the wider hub increasing clearance between the drivetrain and the tire. That being said, when designing our current platform of bikes, Chief Enginerd Matt put on his designer hat to solve this problem without resorting to proprietary wheels and hubs, because that just wouldn’t be the GG way.
Our solution: GG bikes use an asymmetric rear suspension with a 3 mm offset Boost 148 hub in order to achieve three main design goals:
- Wide tire clearance by moving the drivetrain farther away from the rear tire.
Why? Because big tires have big traction.
- Stiffer, stronger rear wheels by allowing equal spoke tension on both sides of the rear hub. Why? Because blowing up rims looks better on camera than in the backcountry.
- Shorter chainstays by moving the chainline outboard. Why? Because we like wheelies and slapping corners.
Pros of sticking with Boost 148 hubs:
- The dominant industry standard
- Lots of hub options
- Plenty of pre-built wheel options
- Increased heel clearance
- Boost hubs are typically lighter than DH hubs
- Narrower rear spacing tucks the rear derailleur in, protecting it in harsh terrain
- Equal spoke tensions on both sides of the rear hub
The rear rim on a current-generation GG bike requires a 3 mm dish to center the rim and tire along the centerline of the frame; the front uses standard 15x110 Boost spacing. This 3 mm dish is not a large enough change to warrant different spoke lengths when building custom wheels or dishing an existing Boost 148 wheel to spec. We’ll take care of this on all complete bike orders, but it is something to be aware of when starting from a frameset-only build. Don’t hesitate to give us a ring if you have any questions about dishing or building wheels for our bikes.
Putting it all together, our bikes require a slightly different 55 mm chainline to play nicely with the offset Boost 148 rear hub. Since the rear hub is offset 3 mm outboard, the chainring must also move outboard from a standard 52 mm Boost chainline in order to maintain shifting performance. Below are a few suggested crank setups:
- Gnarnivore's Pick: Race Face CINCH cranks with a 143 spindle use a 3 mm offset chainring (standard Boost ring)
- Runner Up: Race Face CINCH cranks with a 134 spindle use a flipped 3 mm offset chainring. This is the most commonly found CINCH spindle and chainring.
- SRAM GXP alloy cranks require a zero-offset chainring. Crank arm clearance is normally very tight to the chainstays.
- SRAM GXP carbon cranks are not recommended due to the thickness of the crank arms.
- Shimano cranks require 2 mm of spindle spacers on the drive-side.