Juggernaut Ultra FS. Upgraded brakes, chose 1000 W battery, added Jones bars, Magura dropper, and Surley Bud 4.8 front and Edna rear tire. Ride in the desert and surrounding mountains in Borrego Springs, CA. Terrain is sandy, rocky, typical elevation change is 1000 to 4000. The bike is spectacular in all these conditions: tons of power, exceptional suspension, more than sufficient braking power and an overall comfortable ride. In spite of its weight (75+ lbs) had no trouble powering up the dunes at Blowsand and then up Hawk Canyon. Its weight and long wheel base take a little getting used to, but it does not take long. My riding buddy has a top-of-the-line carbon fiber bike tricked out with everything, including electronic shifters and at least 20 lbs less. The Juggernaut performs every bit as well and has the added benefit of a significantly longer battery life and a control panel that is easy to use, large enough to see and fully informative. Absolutely love the bike. Suggestions: a dropper, larger more aggressive tires, better handle grips and pedals are a must for a serious rider. The 1000 watt battery provides much more torque, but under difficult conditions does not add much to the distance. Don't know what I'd do without it, but do not get more than 30 miles out of one charge. (The larger tires raise the bike so that now I don't tend to run my pedals into the rocks.) If you are in the market for a bike that will get you anywhere, go no further. The Juggernaut Ultra FS is the real thing.