hub (around 300%), selectable at any ratio within the range. With most bikes, the bicycle gearing may be scaled up or down as needed, for example by installing a smaller chainring in front and/or larger sprocket in back to facilitate climbing. Hub gearing permits the use of a fully enclosed chaincase, which minimizes the need for maintenance. A hub gear has lower efficiency than a clean, properly adjusted derailleur system, but retains its efficiency without conscientious cleaning and adjustment. A hub gear system is heavier than a derailleur system. In a hub gear system, the main moving parts are enclosed, making repair more difficult than with a derailleur system. If a geared hub fails, it is sometimes more economical to replace the hub than attempt to repair it. Angled-back handlebars A European city bike has angled-back handlebars and an upright riding position. The handlebars, similar to the North Road style handlebars, have a moderate rise and are swept back toward the body, enabling a fully upright posture similar to a person walking. The rider is easily visible to other traffic and can easily see traffic and hazards. The handlebar's shape allows shopping bags, locks, and other items to be hung from the bars without slipping off. This reduces steering control, but that is compensated by the more stable geometry of the frame and forks. Stable geometry A curved fork and angled vertical tubing provides stable, non-twitchy steering, enabling the rider to ride with one hand, while freeing the other hand for signalling or to secure a load on the rear rack. Europeans commonly use the free hand to hold an umbrella or cell phone, or to hold the shoulder of a child riding their own bike, to train the child for positioning on the road. A coaster brake further enables such one-handed riding, because the one hand on the handlebar only has to steer, not also brake. A stable European city bike enables securely travelling along in a position that is as upright as walking; it feels stable and relaxed, like walking very fast. A safe city bike needs to be capable of easily turning without falling over, and needs to be capable of moving reliably with shopping bags and a lock hanging from the handlebars. Hub dynamo, automatic lights and magnetic lights A hub dynamo enables a built-in lighting system without the loud noise and high drag of a