Fat bike with standard BB width

Fat bike with standard BB width

Tumbleweed have introduced the first production fat bike with standard BB width, called the Prospector. That’s a good thing as it gives you a standard Q factor (the distance between right and left crank arms, if you like). This in part has been achieved with a proprietary hollow cast BB yoke (designed by Anna Schwann).


The evolution of the fat bike continues…

The Prospector is designed to be rugged, adaptable, and to carry a load, even after the trail ends. The Prospector is the first production Fat Bike to use a standard 73mm bottom bracket and can handle a variety of tire sizes and wheel combinations, up to a 4” tire. Utilizing common mountain bike parts and existing standards, allowing for easy and affordable part sourcing – a necessity when traveling in remote or international locations. Designed around the 14 speed Rohloff hub for maintenance free shifting, the Prospector is also front and rear derailleur compatible.


A custom bottom bracket yoke and 73mm Phil Wood EBB (Eccentric Bottom Bracket) allows for maximum tire and mud clearance while maintaining a narrow pedaling stance and allowing the use of many off-the-shelf mountain bike cranks. The EBB allows the rider to set BB height and tension the chain, all while keeping the rear wheel locked in the correct position.

Fat bike with standard BB width


But it’s not just a fat bike…

Tire clearance for 26×4″ on 65mm rim (Rohloff SPEEDHUB or singlespeed only), 29×3.0″ on 50mm rim, or 27.5×3.25″ on 50mm rim. So choices aplenty to build up a very decent adventure bike.

With over a decade of researching, building, and riding various off road touring bikes in the harshest terrains worldwide, Tumbleweed breaks the mold on production bikepacking frames. The Prospector is the most comfortable and practical touring fat bike brought to the market, and the first truly narrow Q factor production fatbike.


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