Lean angle is a crucial variable in determining the dynamic behavior of two-wheeled vehicles. As such, its knowledge is needed to enhance active safety via traction, braking and stability control systems. To estimate the roll angle, this paper proposes a method that employs a reduced set of sensors with respect to existing solutions; namely, two accelerometers and a gyroscope are needed. Notably, it does not require the knowledge of the speed signal, which can be unavailable and/or affected by significant uncertainties when large accelerations/decelerations occur. The estimation performance are analyzed based on experimental data collected on a sport motorcycle at the Imola circuit.