Fat and Semi Fat tire bikes aren't exactly ignored by the industry, as they are quite popular, but owners still struggle to find accessories that are optimal for the specific needs of the bikes while out riding, like the large volume, lower pressure tires. Specialized delivers the compact Air Tool Big Bore Pump, which comes with a bottle boss mounting bracket so you always have a usable inflation option while riding. It packs a massive 90cc's of volume-per-stroke, delivered via a stored flex hose that carries an oversized press-on head for Presta and Schrader valve use. The pump and head were designed for year round use, with features that are feasible with winter gloves on, making it perfect for backcountry winter fat biking.

The Big Bore has an inverted barrel design that allows for high volume in such a compact size. Specialized identified grip requirements and used targeted coarse machining of the aluminum barrel components to ensure you have the control you need. The max pressure rating is 50 psi, making it acceptable for plus size mountain tires and the larger Fat Bike options- but keep in mind 50psi may require serious effort. Most plus tires are ridden well below 35psi in most conditions, and most fat tires rarely see over 20psi, both of which are attainable in a reasonable number of strokes and effort.

Just a few notes on the head and hose. Many people struggle to see how to access the hose, but all you have to do is push upward with your thumbs on both sides of the cradled head and it will release to expose the hose. The head is a push-on design, one side for Presta, one side for Schrader, so make sure the side you want to attach is exposed for the push-on then grabs and recedes into the head. To release, hold the head and push on the opposite side, which will push out the mechanism and release on the valve side. Do not just pull the head off.