Krampus is my home made, electric, all-wheel-drive, fat bike. It started life as a $200 Mongoose Dolomite from Walmart which on its own it fairly terrible. Its heavy, slow, and geared all wrong. I then cut apart the front wheel and rebuilt it with a 500W electric hub motor. I also built a battery box that mounts in the frame holding 4 batteries with a total capacity of 12Ah at 48V. This setup allows me to pedal the rear wheel and drive the front with a twist throttle. I joke that this is my poor man's torque vectoring system with a squishy human differential. It works great, and has been surprisingly reliable. On the road its capable of over 30MPH at full power while pedaling. It has about a 12 mile range at a comfortable 20MPH cruising speed. Also as fat bikes are intended it can blast through snow off road. Riding through the woods in the snow feels like glade skiing on a bicycle.
This project was built with the idea of getting maximum fun for minimum budget. I could have started with a road or hybrid bike if I wanted max speed, but I think fat tire bikes are funny and would be over built enough to handle the extra weight of the electrical system. I also chose to go with Lead Acid Batteries for cost reasons. It cost about $100 for the batteries. The equivalent system in NiMh or LiPo would have cost 5-7x more. Those batteries would have also been smaller and lighter, but as this was built to be a project and a toy, not a practical vehicle, cost was the driving factor.
Another important aspect of this build was that the stock bicycle was equipped with mechanical cable operated disk brakes. They were garbage, which was fine when the bike could not go fast but as soon as the motor was working it was obvious that the stock brakes were inadequate. They were replaced by a set of hydraulically actuated levers and calipers which enabled Krampus to stop faster than it goes.