Thursday, August 4, 2016

What the Hell is Boost?

   You may have ben hearing of a new trend in mountain bike standards called 'Boost'. What is boost?


   Boost is a new standard of hub spacing. Time for a history lesson:


   Originally, Mountain bikes had 130mm rear hub spacing and a 9mm axle. This was for 7 speed set ups. Upsetting the norm (and a lot of cyclists), manufacturers started using 135mm hub spacing, still with a 9mm axle, which provided a wider and more stable platform for rear wheels. In 2011, we started seeing a new trend spread across the industry: 142mm. This was a 12mm thru axle that could be quickly removed for wheel changes. Different bike companies have different axles, but they all work pretty similar. These are the two common standards - there are a few others out there, but most bike manufacturers are sticking to these.

124mm x 12mm axle

   Boost is a hub standard that increases the spacing of not only the rear, but the front as well:
  • 142mm becomes 148mm (rear) on a 15mm axle
  • 100mm becomes 110mm (front) on a 12mm axle
   In the rear, Boost pushes the hub flanges 3mm outward on each side  to increase the angle your  spokes lean in and therefore increase wheel stiffness. A wider hub is a wider platform to support your rim.

Boost hub

   We have 29ers to thank for this new standard, for a couple reasons:
1. The larger the wheel, the less stiff it is, so large 29" wheels are less stable than a 27.5" or a 26". Boost 148mm is supposed to bring 142mm 27.5" stiffness to a 29" wheel.
2. Stuffing a 29" wheel on an XS frame has always presented a challenge, and wider chain and seat stays make things a bit easier (but you should really be on a 27.5"...).
All of this will add up to give you God-like handling abilities.

Boost on a Trek Remedy

   As pointed out on Art's Celery Blog, there is a fundamental difference between 135/142 and 148: The actual hub spacing of 142 was the same as 135. The extra mm's were frame thickness. This meant you can easily adapt wheels back and forth with a simple axle caps, like the many, many offered by Stan's. The new 148 requires you to take much more dramatic steps, as pointed out in this article about un-boosting your bike using interchangeable dropouts and witchcraft.

   Companies like ENVE are all about it, praising the stiffer, more efficient wheel they can sell you. Other manufacturers are not turning their backs on the current standard so quickly. If you're running 142mm you'll still be able to find wheels to fit your rig for at least as long as it lasts before you are forced to buy something new. Then, maybe Boost will be a good option.

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