Outrigger wheels are used to add stability to a motorcycle without undergoing the full conversion to a trike. The most basic outrigger wheels can be quickly bolted to the frame of a motorcycle, adding a wheel to either side of the rear tire and causing the motorcycle to handle like a motorized tricycle. The process is cheaper than a full conversion and is easily reversible.
More advanced outrigger wheels are designed to add permanent stability to a motorcycle at low speeds without changing its handling at high speeds. These are often referred to as retractable wheels. Retractable wheel systems, which can be installed on many larger motorcycles, are usually made to extend when traveling below about 20 miles per hour and to retract when moving faster. Although these alternatives to trike conversion can sometimes be just as expensive as a full conversion, they are perfect for riders who need added stability when riding but prefer the handling of a motorcycle compared to a trike.
In-between options include the Ghost Wheels brand system. The Ghost Wheel system features outrigger wheels that are not retractable, but that can be locked and unlocked. When locked, the motorcycle handles like a tricycle, but the wheels unlock at higher speeds, allowing the bike to move and lean as if they didn't exist.