Spin? Class Terms. Flat Terrain: Like the outside, flat terrain means to mimic a flat road.Usually this is an easy ride, instructors may do speed drills while on a flat terrain. More: Improve Your Running Skills With Indoor Spin. Gear Up/Gear Down: This means to add resistance or tension.. Hill/Climb: Instructors try to mimic a real road ride.Hill or climb means you add resistance to simulate. Gears are toothed, mechanical transmission elements used to transfer motion and power between machine components, and in this article, we discuss the different types of gears available and how gears work. Operating in mated pairs, gears mesh their teeth with the teeth of another corresponding gear or toothed component which prevents slippage. When you cast a bait casting reel, your spool is spinning freely. The spool's ability to spin freely is the result of the disengagement of the gears. When casting a bait casting reel, you push down on the thumb bar; also, called the spool release button. With the thumb bar down, the gears are disengaged and you're able to cast. Let me explain this with commonly used cylindrical gears. 2. Definition of rotational direction. Generally, a motor is used as the power source when using gears in designing mechanisms of mechatronics products. Rotational direction of the motor is defined by the rotation of the shaft as seen from the side the motor shaft projects out. (Figure 2-1) By the way, the spin to the right is.