the same board and the same rider is involved in beginning a maneuver such as a slalom turn or a rearward 180 u00b0 or 160 u00b0 turn in this case the rider 39 s foot is interceptably positioned differently with respect to fig5 but the force of the foot 24 is applied not only vertically but generally in the direction of the arrow x shown in fig6 in this case the arm 22 is again pivoted downward but likewise is pivoted around the axis b shown in fig4 and the shoe 30 engages wheel 16 while the shoe 31 remains free of wheel 18 under these circumstances wheel 16 is either totally or partially locked and the rider may make a sharp near 180 u00b0 turn while moving or while stopped or may make a 180 u00b0 or 360 u00b0 turn more easily and with greater control than heretofore even with the rider in the same stance as shown in fig5 and 6 he may accomplish braking on the opposite wheel 18 while leaving wheel 16 free to turn as shown in fig7 in this case again the foot 24 is moved almost imperceptably to the left hand side of the board with the front part of the heel engaging the arm 22 and the ball of the foot engaging the board 12 at the rear tail 26 in this case the force of the rider 39 s weight is applied in such a manner as to deflect the arm 22 and at the same time deflect the.