“Another new ‘bike industry standard’ again??? You sons a…!!!” Yep, we’ve heard it all. And even though we’re in the industry ourselves, we know “old” parts that still work well deserve a place at the new table too. In this case, we’re talking about hubs and the new front and rear axle spacing called BOOST.
The once “standard” thru axle spacing - 100mm (front) and 142mm (rear) - becomes 110 mm (front) and 148 mm (rear) with BOOST (check out the images below). The extra width increases wheel strength and adds design flexibility as tires get wider and chainstays get shorter. Wider hub shells lead to better bracing angles of the spokes, which in turn yields a stronger and stiffer wheel. On wheels of the 29-inch diameter, this is especially beneficial, but all sizes can feel the love.
Front hub spacing: traditional (left) and Boost (right)
Rear hub spacing: traditional (left) and Boost (right)
Problem Solvers Booster Wheel Adapters fill in the gap from the previously standard (100/142) to the wider (Boost) frame spacing and re-position the disc brake rotor to line up with the brake caliper. Using the Front Booster is pretty straightforward, because the additional spacing is equally shared between both sides.
However, there are some adjustments to be made in the case of the Rear Booster because all 6mm of additional is taken up on the non-drive side. This is done to maintain drivetrain functionality, keeping your cassette in place.
To use the kit, you’ll need to re-dish the rear wheel. That means moving the wheel back to center (compensating for the shift caused by the spacer). If you’re looking at your bike from behind) by tightening the spokes that pull to non-driveside (the side of the hub without gears) and likely loosening the spokes that pull to the drive-side. The spacer from the kit is what makes your existing hub fit in the BOOST spacing, but it’s also the culprit for this re-dishing need. Luckily the spacer works as the perfect tool to accurately re-dish your wheel.
If you’re unfamiliar with truing a wheel, re-dishing is one more step outside your wheel house. You’ve got alignment side-to-side and up and down, and spoke tension to deal with too. Missing the mark in any of these areas can adversely affect the performance of the bike, or even cause wheel failure. Bring the wheel to your local shop if you don’t have the experience.
Unless you’re using a new crank with chainring placement optimized for BOOST, your chainline with your current “Standard” crank and current “Standard” rear hub should not be affected by the addition of the Problem Solvers Rear Booster Kit. If you experience poor shifting or chain rub on the tire, the chainline needs to be addressed. Again, this is something for your local shop if you’re unfamiliar with chainline.
At some point, we’ll have to talk about Super Boost Plus, but that’s a whole ‘nuther enchilada.