
I had originally thought I might build from scratch, but it became obvious I wouldn't have the time. I looked around online for local used options that would be suitable for fat tire modifications, and I was exceeding lucky to find this trike for sale at a police auction nearby. It is an Earth Cycles Dragonflyer. I have read they were hand made locally, but they went out of business in 2001. It was a high-end product at the time, with upgrades for Phil Wood hubs and early hydraulic disc brakes.
The most unique aspect that helped my plans significantly was the rear swing arm with an elastomer shock. This meant I could simply make a new, longer swing arm and swap these parts. Even easier, this part was completely orthogonal and was originally made with standard chromoly tubing. I dusted off my welder for the first time in years, and ended up with sloppy but functional welds. I also removed both derailleurs in favor of a fixed gear 3 speed hub. I thought it might be nice to go in reverse to get unstuck from snow piles. I am using "standard" fatbike rims and tires laced to new hubs. Essentially all of the modifications are reversible if I ever want to sell or use it as a stock trike. It would take several hours, so I doubt I will do it each year. I mostly wanted it for winter use.
I have been out several times, and I think it was a great success. I hadn't thought of this, but I found that getting unstuck from snow is actually relatively easy when using your hands to push the front wheels like a wheelchair. The fixed gear is still useful for other reasons but maybe not how I originally planned. It is generally up and running fine, although I might make a tire chain for the rear drive as I do spin out when the snow gets a couple inches deep, especially pulling a trailer.
I have been looking around to see if there are other similar creations, and there are very, very few. A couple big companies have dabbled with some bald fat tire customs. Just recently, the most notable was a custom rig, not too different from this (but with lots more gears), used in a successful bike expedition to the south pole. As of writing, the cyclist had reach the pole, but she hasn't finished the return journey. Hopefully it goes well:
http://marialeijerstam.blogspot.com/
I suppose it might be another year, before I have much else to share, but at least I hope I will be out enjoying myself.