Honda Motorcycle VT1100C3 Shadow Aero Turn Signal Bulb Size
Honda Motorcycle VT1100C3 Shadow Aero front turn signal bulbs measure P21/5W while rear turn signal bulbs measure P21W in size. The replacement chart covers 1998 to 2002 model years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Honda Motorcycle VT1100C3 Shadow Aero uses two distinct bulb types across its turn signal positions for the 1998-2002 model years: the P21/5W at the front and the P21W at the rear.
The P21/5W is a dual-filament bulb rated at 12V with a 21W primary filament and a 5W secondary filament, mounted on a BAY15d bayonet base.
The BAY15d base features offset pins, a design that physically prevents incorrect filament orientation during installation.
The P21W is a single-filament bulb rated at 12V, 21W, and uses a BA15s bayonet base with symmetrically placed pins.
Because the P21/5W and P21W share a similar physical profile but differ in base type and filament count, the two are not interchangeable between front and rear positions.
The BA15s base of the P21W accepts only single-filament bulbs, while the BAY15d base of the P21/5W is keyed specifically for dual-filament fitment.
Both the P21/5W and P21W conform to ECE standards, a regulatory framework recognized across Europe and numerous other markets worldwide.
The front turn signal position on the VT1100C3 Shadow Aero uses the dual-filament P21/5W, which is typical of applications where a single housing serves both a turn signal and a secondary function such as a running or position light.