A vehicle comprising: an engine; at least one driven wheel rotating under the influence of the engine to move the vehicle; a speed control handle pivotable about a first axis through a range of motion to control the rate of rotation of the driven wheel, the speed control handle including an engaging portion that moves along a path in response to pivoting of the speed control handle; a cam member pivotable about a second axis, a stop portion of the cam member being the portion of the cam member in the path of the engaging portion of the speed control handle for a given position of the cam member; a frictional member creating sufficient frictional forces to resist movement of the cam member with respect to the rest of the vehicle during ordinary operation of the vehicle; and a handle manipulatable by an operator of the vehicle to overcome the friction created by the frictional member and rotate the cam member into a desired position; wherein the engaging portion of the speed control handle abuts against the stop portion of the cam member to define an end of the range of motion of the speed control handle such that the range of motion of the speed control handle is limited; characterized in that the second axis is vertical and perpendicular to the first axis, and in that the cam member has a varying thickness, and in that the handle and the cam member are integrally formed as one piece, and in that the desired position of the cam member corresponds to a desired thickness of the stop portion of the cam member, and the range of motion of the speed control handle is limited as a function of the thickness of the stop portion of the cam member that is rotated about said second axis into the path of the engaging portion of the speed control handle. an engine; at least one driven wheel rotating under the influence of the engine to move the vehicle; a speed control handle pivotable about a first axis through a range of motion to control the rate of rotation of the driven wheel, the speed control handle including an engaging portion that moves along a path in response to pivoting of the speed control handle; a cam member pivotable about a second axis, a stop portion of the cam member being the portion of the cam member in the path of the engaging portion of the speed control handle for a given position of the cam member; a frictional member creating sufficient frictional forces to resist movement of the cam member with respect to the rest of the vehicle during ordinary operation of the vehicle; and a handle manipulatable by an operator of the vehicle to overcome the friction created by the frictional member and rotate the cam member into a desired position; wherein the engaging portion of the speed control handle abuts against the stop portion of the cam member to define an end of the range of motion of the speed control handle such that the range of motion of the speed control handle is limited; characterized in that the second axis is vertical and perpendicular to the first axis, and in that the cam member has a varying thickness, and in that the handle and the cam member are integrally formed as one piece, and in that the desired position of the cam member corresponds to a desired thickness of the stop portion of the cam member, and the range of motion of the speed control handle is limited as a function of the thickness of the stop portion of the cam member that is rotated about said second axis into the path of the engaging portion of the speed control handle.