17 lines (15 with data), 608 Bytes

//This is the joint which connects the Pelvis segment to the bike.
AnyRevoluteJoint BikeGroundJoint ={
  Axis = z;
  AnyRefNode & crank  = .BikeModel.BikeFrame.SaddelPos;
  AnyFixedRefFrame &ground = Main.GlobalRef;
};

AnyKinEqSimpleDriver BikeGroundRotation = {
  AnyRevoluteJoint &Jnt = .BikeGroundJoint;
  DriverPos = {0};
  DriverVel = {0};
  //Setting Reaction.Type=1 means that the joint will generate the moment it will 
  //need to balance this DOF, setting it to 0 which is default will mean that muscles 
  //forces will be used for balancing the joint
  Reaction.Type = {On}; 
};