The Xdream is the first indoor fitness product that accurately simulates the experience of riding outdoors. Real feel gears, brakes, handle bars, pedal, cranks and seat sensors enable each move the rider makes to be accurately portrayed within the experience. The bikes resistance accurately depicts the terrain gradients, track surfaces and conditions. There are 4 different terrains to test your riding ability. There's Parkland, Semi Arid, Desert and Highlands. When you get to the advanced and pro levels your bike choice makes a real difference in terms of handling. Each of the 4 terrains has different tracks with increasing difficulty. You start on the Green trails then move to the Blue, Red, Black and then the toughest White trails. You must complete these trails in beginner mode in order to move on to intermediate, advanced and then Pro levels.