What is the boost?
The Boost is a new standard that can be found recently on the wheels (hubs) and transmission, which appeared in 2015. The Trek Remedy was the first bike equipped with the Boost technology. Subsequently, this standard has been adapted to the different components (fork / hub / pedal / chain ring) for a perfect compatibility with the frames that adopt this format. For the record, the concept was developed by the manufacturer of Sram components at the request of Trek which wanted to improve the rigidity of its 29'' enduro / All-Mountain wheels.
The Boost format gives a real advantage, it allows a total gain of 6 mm between the flanges on a rear hub and 10 mm on a front hub. Therefore, the larger angle of the spokes increases the lateral stiffness by 20% for a 29" wheel and about 14% for a 27.5'' wheel. This change will be noticeable for use in relaunches or sudden changes of direction for example.
The modification of the width of the rear hub has a direct influence on the frame: the geometry is rectified, the bases are shortened and the bracket is also enlarged by 3 mm, the space between these two bases is therefore more important to make room for a large tyre of the "Plus" standard (27,5+).
- Increased stiffness and durability of the wheel
- More efficient and precise steering
- Better geometry for short-base frames
- Bigger and more rigid points for the steering tube
- More choices in terms of flat-teeth chain ring
- More tyre travel, allowing you to mount wider sections
- A 29" wheel gains 20% lateral stiffness
- A 27.5" wheel gains 14% lateral stiffness
- The offset of the chain increases the space between the tyre and the chain, allowing the fitting of tyres of more than 2.5"
Technically: what does it change?
The aim of this technology is to widen the hub dimension at first, from 142 mm to 148 mm for a rear hub and from 100 mm to 110 mm for the front one. There are numerous options available to obtain a gain in rigidity at this level, and this is the one the manufacturer Sram has retained as its solution, which generates about zero additional mass.
This first modification is the widening of the rear hub's body, which goes in pair with a chain line offset by 3 mm. We refer to it as a chain line to determine the ideal distance between the centre of the crank axle and the teeth of the chain ring. This value ensures optimum chain operation, fluid gear shifting on all sprockets and non-premature wear of the components.
In the second stage, this shift also affects the bottom bracket which is in turn enlarged by 3 mm left and right to keep the Q-Factor. However, it's necessary to use a chain ring with a 3 mm offset to the outside.
Compatible Boost transmission
So far, some manufacturers have developed a clean range allowing a perfect adaptation to this format: Sram and Shimano are the main players in terms of compatible pedals.
- XX1 Eagle / XO1 Eagle (1x12 speeds)
- XX1 / XO1 / GX-1000 / GX -1400 / X1-1400 (1x11 speeds / 1x7 speeds)
- GX-1000 / GX-1400 (2x11 speeds)
- GX-1000 (2x10 speeds)
- XTR FC-M8000-B1 / SL FC-M7000-11-B1 (1x11 speeds)
- XTR FC-M8000-B2 / SL FC-M7000-11-B2 (2x11 speeds)
Boost Component Dimensions
- Fork: centre distance 110 mm / axle diameter 15 mm
- Chain ring: 3 mm offset
- Hubs: Front 15x110 mm / Rear 12x148 mm
- Front axle: 15x110 mm
- Rear axle: 12x148 mm
Is it possible to adapt a pair of wheels to the Boost standard (12x148 mm) on a non-boost frame (12x142 mm) for example?
Unfortunately no, it would be too simple to be able to benefit from a gain of rigidity without having to change your frame. However, the reverse is possible! For those who wish to keep their pair of wheels in 12x142 mm, some brands have thought so far of a conversion kit allowing a perfect compatibility with frames to the Boost standard, for example: Specialized to convert your Roval model, or the small French brand Hxr components which proposes a universal kit only compatible with a fixation system of disc 6 holes (Photos HXR1 / HXR2)
Can a dual transmission (2x11 speeds) fit on a Boost frame?
The current trend of the industry goes towards the transmission of 1x11 speeds. More and more enduro / all-mountain bicycles are fitted with this standard. Only the Sram and Shimano brands offer a double bottom bracket in the Boost standard so far.
- Boost standard: The Boost is a new standard for wheels (hubs) and the transmission.
- Chain line: The chain line is the distance between the centre line of the frame and the centre line of the chain ring (single-chainring configuration). Ideal Boost value 51-53 mm / Ideal non-Boost value 48-50 mm.
- Offset: The offset of a chain ring is the distance between the base of the chain ring and the centre line of the teeth, (0 mm, 3 mm, 6 mm).
- Q-factor: The Q-factor of a pedal is the distance between the two cranks (156 mm, 158 mm, 166 mm, 168 mm).
- Front or rear axle: The cross-axle is used for fixing the wheel, this model fits into the frame and is tightened with a screw thread integrated into the frame or with a nut.