• The Omnium Portable Bike Trainer comes in two versions, the Over-Drive,  resistance model, and the Zero-Drive, non resistance version.
• The Over-Drive version features Internal Progressive Resistance that utilizes the power of an eddy current. In short, the faster you ride the more resistance is applied, there is no adjustment to add or reduce the resistance, you simply use the gears on your bicycle just like outside. 
• The Omnium Over-Drive has an internal progressive resistance. The faster your rear wheel spins the more resistance you will get. You can see in the resistance chart as your rear wheel speed increases so does the resistance. If you would like to reduce the resitance you can simply switch to an easier gear which will reduce your rear wheel speed. 
• The Zero-Drive trainer offers no resistance. This trainer is great in cases of single speed bikes (such as track bikes) or for a very basic low exertion warm up or cool down trainer. **This data was based on a 150lb rider riding on a standard road bike with 700x23 tires at 100 psi. Changing the rider weight, tire size, or tire pressure will change the resistance curve.