BMW Motorcycle R100 front and rear turn signal bulbs utilize a P21W size across all applications. The replacement chart covers 1976 to 1995 production 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 BMW Motorcycle R100 uses the P21W bulb for both front and rear turn signals across all listed model years from 1976-1995.
The P21W is a single-filament bulb, meaning it serves one lighting function only, which is consistent with its dedicated turn signal role on the R100.
P21W bulbs operate at 12 volts and 21 watts, placing them in the standard range for automotive turn signal applications.
The P21W uses a BA15s bayonet base, where "BA15s" denotes a single-contact bayonet fitting with a 15mm pin spacing. This base type is not interchangeable with dual-contact BA15d variants.
The P21W designation follows ECE (Economic Commission for Europe) standards, indicating the bulb is specified for European and worldwide markets rather than SAE-governed North American standards.
The front and rear turn signal positions on the BMW Motorcycle R100 share the same P21W specification across all listed years, meaning both positions draw from the same bulb type.
Because the BA15s base is a single-contact design, substituting a dual-contact bayonet bulb such as a BAY15d-based type would result in an incompatible fit despite the similar physical appearance of the base.