I live near an (30-50 mile) asphalt trail that meanders off onto horse trails and near the trails along the North Branch of the Chicago River. I decided to buy a Fat Bike, for the winter only, as my other riding/training is all road/track during the non-snow months. I didn't want to spend a lot of money but wanted something that was lighter and that I could swap parts out if need from my bins in my shop. I ended up going with a Mongoose Vinson about 3 years ago.* I pulled it apart, rebuilt some of it and used mostly parts that I had about albeit I did buy some stuff for it. Since it is an only winter bike, I invested in some Surly Nates and I put some BB7's on there as well as a Deore RD, Sun Race thumb shifters, new headset, carbon bits (stem/bar/seatpin), some SPD's and an Aspide white saddle.*** Made my own rim strips as well. The bike is now around 30 pounds and suits the intended purpose perfectly for what I need. It was only 10F here today but I rode for about 2.5 hours. What a great way to get outside on your bike in the snow.
*paid $297** for it on a Black Friday Sale
**steal
***ride those on all my bikes