A sissy bar, also called a "sister bar" or "passenger backrest" is an addition to the rear of a motorcycle

Motorcycle

A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...

 that allows the rider or passenger to recline against it while riding. Alternately it can serve as an anchor point or support for cycling supplies that are not part of the bike, including spare helmets, backpack

Backpack

A backpack is, in its simplest form, a cloth sack carried on one's back and secured with two straps that go over the shoulders, but there can be exceptions...

s, or sleeping bag

Sleeping bag

A sleeping bag is a protective "bag" for a person to sleep in, essentially a blanket that can be closed with a zipper or similar means, and functions as a bed in situations where a bed is unavailable . Its primary purpose is to provide warmth and thermal insulation...

s and other camping gear or items a rider feels is needed, such as tool-kits, map books, and sometimes a GPS or higher quality camera.

Sissy bars for cruiser-style motorcycles are usually affixed to the rear fender strut

Strut

A strut is a structural component designed to resist longitudinal compression. Struts provide outwards-facing support in their lengthwise direction, which can be used to keep two other components separate, performing the opposite function of a tie...

s, and are typically made of chrome-plated steel with a foam padded seatback for comfort. Some elaborate custom examples can extend three feet or more and often serve as mounts for novelty flags. A backrest for a touring motorcycle

Touring motorcycle

A touring motorcycle is a type of motorcycle designed for touring. Although any motorcycle can be used to tour with, manufacturers have brought specific models designed to address the particular needs of these riders...

 is often shorter and less elaborate and may be built into a top box.

Inspired by its motorcycle counterpart, a smaller version of the sissy bar was a common feature on 1960s- and 70s-era wheelie bike

Wheelie bike

A wheelie bike, also called a muscle bike, high-riser, or banana bike, is a type of stylized children's bicycle designed in the 1960s to resemble a chopper motorcycle and characterized by ape hanger handlebars, a banana seat with sissy bar, and small wheels. Notable examples include the Schwinn...

s, such as the Schwinn Sting-Ray and the Raleigh Chopper

Raleigh Chopper

The Raleigh Chopper is a children's bicycle, a wheelie bike, manufactured and marketed in the 1970s by the Raleigh Bicycle Company of Nottingham, England. Its unique design became a true 70s cultural icon, and is fondly remembered by many who grew up in that period...

. This extended backrest, which attached to the rear of the bike's banana seat, gave a passenger something to lean back on and hold onto besides the rider doing the pedaling.