If the motors are attached to the vehicle body, flexible couplings are required but not if the traction motors are integrated into the wheels. One disadvantage is that the unsprung mass increases and suspension responsiveness decreases, which impacts ride and potentially safety. However the impact should be minimal as electric motors in wheel hubs such as Hi-Pa Drive, may be very small and light having exceptionally high power-to-weight ratios and braking mechanisms can be lighter as the wheel motors brake the vehicle.