You wnt your elbows to have a slight bend in them. If they are completely straight, every little bump that travels up the front of the bike is grinding the bones of your arrm together at the joints. Too much bend stresses the ligaments and tendons. The other part of the equation is that you want to have most of your weight OFF your upper body. You need to develop your core (lower torso) so that your upper body can support itself better. Pilates, Core Board, ab workouts, etc. will all help stabilize your upper body and improve your posture and balance. The fitness center I teach Spinning at added a 15 min. ab workout to the evening Spinning classes for exactly that reason.