Originally Posted by fujibike

I've had the same experience. It's likely due to prolonged pressure to the Ulnar nerve that runs down your arm through your hand. Well padded gloves, position changes while riding (drops/flats/hoods), arm stretching, and saddle position can ease/eliminate the problem. Keep your elbows bent. Consider a slight tilt upward on your saddle to help move weight to your sit bones vs you hands, or try moving the saddle forward a bit.