I designed and built Tatanka specifically for long-term off-road touring abuse. I chose a similar riding position to my Surly Long Haul Trucker, because it is so gloriously comfortable on those 18 hour days. With 6 inches of extra wheelbase for better load handling, and a raised head tube for front suspension, resemblance to any other bike I have ever seen fades away.
While flexy frames create a softer ride, they drive me crazy when I am mashing up a hill and the bike starts shimmying like a... well, shimmying has its place. My bike's frame is not that place. I put stiffness as a top priority in geometry and tubing specs. The joints are brass brazed. The tubing is double butted 4130 Chromoly up front and tapered 4130 in the rear. The dropouts are Paragon Machine Works stainless sliders with aluminum inserts. All said and done, the frame weighs 7lbs 2oz. Why did I go to all that trouble to braze my frame? I can perform an effective repair with a torch anywhere in the world. I like the way it looks and feels. Brazing creates less of a stress concentration around the joint due to the HAZ than TIG welding. Production frames are not made this way because brazing is more expensive, takes far longer, is more difficult, and adds more weight than TIG welding. I powder coated the frame in clear so I can easily inspect all the joints for signs of damage.
I built the wheels, too-- Phil Wood / Mavic Ex729 / Sapim 2.3mm in front with the Rohloff 14'speed hub and same spoke/rim combo in the rear. Tires are Schwalbe Marathon XR 2.25 x 26. The Rohloff offers a 526% gear range. That means that my biggest gear is 5.26 times faster than my lowest gear at a constant RPM. A standard mountain bike 27 speed system (22/32/44 crankset with a 11-34 cassette) gives 618% gear range. The Rohloff is about 15% less range. So, instead of topping out at 35mph, you'd spin out at 30mph. While touring, this is not a big sacrifice.
The racks are stout. 3/8" OD x .065" wall 4130 tubing with full TIG welds and aluminum decks made from old street signs. The front rack mounts to the frame instead of the fork, allowing me to keep the steering light but still carry a load up front. The limit to this concept is that the contents of the rack must sit below the handlebars and still clear the range of motion of the wheel.
I love the way Tatanka handles, from smooth pavement to rough tracks. The only downside is that the ride is rough when the bike is unloaded. But 99% or more of my trip will be loaded, so I don't really care.
All the pictures of the build process, with captions can be seen here.
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| Click here to see pictures of how to build your own custom bicycle frame... |
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| 2003 Suzuki DR200 at Salar de Uyuni, Bolivia |
