This is a great way to improve your driving skills and become more comfortable with the mechanics of your vehicle. Gear changes are an important part of driving, and practicing them can help you become a better and safer driver. This practice will help you become more familiar with the feel of the gear changes
From Wikipedia
A fixed-gear bicycle or fixie is a bicycle that has a drivetrain with no freewheel mechanism, meaning the pedals always spin together with the rear wheel. The freewheel was developed early in the history of bicycle design but the fixed-gear bicycle remained the standard track racing design. More recently the "fixie" has become an international subculture mainly among urban cyclists.