Biomechanical Model Cycling.txt

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Biomechanical Model Cycling.txt
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  1. Theoretical: Vertical Ground Reaction Force
    *speed up*

    A larger vertical ground reaction force creates greater friction force and greater external force to push against. Greater external force to push against allows greater ankle plantar flexion muscle force, ankle dorsiflexion muscle force, knee extension muscle force, knee flexion muscle force, hip extension muscle force, and hip flexion muscle force to be exerted.

    Greater ankle plantar flexion muscle force creates greater ankle plantar flexion joint torque and greater ankle plantar flexion angular velocity. Greater ankle plantar flexion angular velocity creates greater linear speed of the ankle and all joints distal to the ankle. 

    Greater ankle dorsiflexion muscle force creates greater ankle dorsiflexion joint torque and greater ankle dorsiflexion angular velocity. Greater ankle dorsiflexion angular velocity creates greater linear speed of the ankle and all joints distal to the ankle.

    Greater knee extension muscle force creates greater knee extension joint torque and greater knee extension angular velocity. Greater knee extension angular velocity creates greater linear speed of the knee and all joints distal to the knee.

    Greater knee flexion muscle force creates greater knee flexion joint torque and greater knee flexion angular velocity. Greater knee flexion angular velocity creates greater linear speed of the knee and all joints distal to the knee.

    Greater hip extension muscle force creates greater hip extension joint torque and greater hip extension angular velocity. Greater hip extension angular velocity creates greater linear speed of the hip and all joints distal to the hip.

    Greater hip flexion muscle force creates greater hip flexion joint torque and greater hip flexion angular velocity. Greater hip flexion angular velocity creates greater linear speed of the hip and all joints distal to the hip.

    This coordinated increase in joint linear speeds is the result of modifying a factor that speeds the body up (vertical ground reaction force) and results in greater linear speed for the road cyclist and a decrease in movement time.
  2. Real-World: Vertical Ground Reaction Force
    to create a larger vertical ground reaction force, you must ride on the hardest surface available
  3. Theoretical: Coefficient of Friction
    *speed up*

    A larger coefficient of friction creates greater friction force and greater external force to push against. Greater external force to push against allows greater ankle plantar flexion muscle force, ankle dorsiflexion muscle force, knee extension muscle force, knee flexion muscle force, hip extension muscle force, and hip flexion muscle force to be exerted.

    Greater ankle plantar flexion muscle force creates greater ankle plantar flexion joint torque and greater ankle plantar flexion angular velocity. Greater ankle plantar flexion angular velocity creates greater linear speed of the ankle and all joints distal to the ankle.

    Greater ankle dorsiflexion muscle force creates greater ankle dorsiflexion joint torque and greater ankle dorsiflexion angular velocity. Greater ankle dorsiflexion angular velocity creates greater linear speed of the ankle and all joints distal to the ankle.

    Greater knee extension muscle force creates greater knee extension joint torque and greater knee extension angular velocity. Greater knee extension angular velocity creates greater linear speed of the knee and all joints distal to the knee.

    Greater knee flexion muscle force creates greater knee flexion joint torque and greater knee flexion angular velocity. Greater knee flexion angular velocity creates greater linear speed of the knee and all joints distal to the knee.

    Greater hip extension muscle force creates greater hip extension joint torque and greater hip extension angular velocity. Greater hip extension angular velocity creates greater linear speed of the hip and all joints distal to the hip.

    Greater hip flexion muscle force creates greater hip flexion joint torque and greater hip flexion angular velocity. Greater hip flexion angular velocity creates greater linear speed of the hip and all joints distal to the hip.

    This coordinated increase in joint linear speeds is the result of modifying a factor that speeds the body up (coefficient of friction) and results in greater linear speed for the road cyclist and a decrease in movement time.
  4. Real-World: Coefficient of Friction
    The rear tire should have a greater coefficient of friction than the front tire. To accomplish this, the rear tire should have the following characteristics compared to the front tire:

    (1) the rear tire should be made of softer materials than the front tire

    (2) the rear tire should have a rougher surface than the front tire

    (3) the rear tire should have lower air pressure than the front tire
  5. Theoretical: Muscle Force
    In order to use all torques possible, the foot must be securely connected to the bicycle pedals (pushing down/pulling up)

    For the ankle muscle force box:

    Greater ankle plantar flexion muscle force creates greater ankle plantar flexion joint torque and greater ankle plantar flexion angular velocity. Greater ankle plantar flexion angular velocity creates greater linear speed of the ankle and all joints distal to the ankle.

    Greater ankle dorsiflexion muscle force creates greater ankle dorsiflexion joint torque and greater ankle dorsiflexion angular velocity. Greater ankle dorsiflexion angular velocity creates greater linear speed of the ankle and all joints distal to the ankle.

    This coordinated increase in joint linear speeds distal to the ankle is the result of modifying two factors that speed the body up (ankle plantar flexion muscle force and ankle dorsiflexion muscle force) and results in greater linear speed for the road cyclist and a decrease in movement time.

    For the knee muscle force box:

    Greater knee extension muscle force creates greater knee extension joint torque and greater knee extension angular velocity. Greater knee extension angular velocity creates greater linear speed of the knee and all joints distal to the knee.

    Greater knee flexion muscle force creates greater knee flexion joint torque and greater knee flexion angular velocity. Greater knee flexion angular velocity creates greater linear speed of the knee and all joints distal to the knee.

    This coordinated increase in joint linear speeds distal to the knee is the result of modifying two factors that speed the body up (knee extension muscle force and knee flexion muscle force) and results in greater linear speed for the road cyclist and a decrease in movement time.

    For the hip muscle force box:

    Greater hip extension muscle force creates greater hip extension joint torque and greater hip extension angular velocity. Greater hip extension angular velocity creates greater linear speed of the hip and all joints distal to the hip.

    Greater hip flexion muscle force creates greater hip flexion joint torque and greater hip flexion angular velocity. Greater hip flexion angular velocity creates greater linear speed of the hip and all joints distal to the hip.

    This coordinated increase in joint linear speeds distal to the hip is the result of modifying two factors that speed the body up (hip extension muscle force and hip flexion muscle force) and results in greater linear speed for the road cyclist and a decrease in movement time.
  6. Real-World: Muscle Force
    To create a larger muscle force, three factors that influence the size of the muscle force must be considered.

    (1) muscle size (increase via training)

    (2) muscle length (120% = most muscle force)

    (3) speed of muscle contraction (contracted slower = more muscle force)
  7. Muscles Involved in Cycling
    Ankle Plantar Flexion:

    • fibularis brevis
    • fibularis longus
    • gastrocnemius
    • plantaris
    • soleus
    • tibialis posterior

    Ankle Dorsiflexion:

    • fibularis tertius
    • tibialis anterior

    Knee Extension:

    • gluteus maximus
    • rectus femoris
    • tensor fasciae latae
    • vastus intermedius
    • vastus lateralis
    • vastus medialis

    Knee Flexion:

    • biceps femoris
    • gastrocnemius
    • gracilis
    • plantaris
    • popliteus
    • rectus femoris
    • sartorius
    • semitendinosus
    • semimembranosus

    Hip Extension:

    • adductor magnus
    • biceps femoris
    • gluteus maximus
    • gluteus medialis
    • gluteus minimus
    • semitendinosus
    • semimembranosus

    Hip Flexion:

    • adductor brevis
    • adductor longus
    • adductor magnus
    • gluteus medilias
    • glutues minimus
    • gracilis
    • iliacus
    • pectineus
    • psoas major
    • sartorius
    • tensor fascia latae
  8. Theoretical: Moment Arm
    For the ankle moment arm box:

    A longer ankle plantar flexion moment arm at the ankle joint creates greater ankle plantar flexion joint torque and greater ankle plantar flexion angular velocity. Greater ankle plantar flexion angular velocity creates greater linear speed of the ankle and all joints distal to the ankle.

    A long ankle dorsiflexion moment arm at the ankle joint creates greater ankle dorsiflexion joint torque and greater ankle dorsiflexion angular velocity. Greater ankle dorsiflexion angular velocity creates greater linear speed of the ankle and all joints distal to the ankle.

    This coordinated increase in joint linear speeds distal to the ankle is the result of modifying two factors that speed the body up (ankle plantar flexion moment arm and ankle dorsiflexion moment arm) and results in greater linear speed for the road cyclist and a decrease in movement time.

    For the knee moment arm box:

    A longer knee extension moment arm at the knee joint creates greater knee extension joint torque and greater knee extension angular velocity. Greater knee extension angular velocity creates greater linear speed of the knee and all joints distal to the knee.

    A longer knee flexion moment arm at the knee joint creates greater knee flexion joint torque and greater knee flexion angular velocity. Greater knee flexion angular velocity creaters greater linear speed of the knee and all joints distal to the knee.

    This coordinated increase in joint linear speeds distal to the knee is the result of modifying two factors that speed the body up (knee extension moment arm and knee flexion moment arm) and results in greater linear speed for the road cyclist and a decrease in movement time.

    For the hip moment arm box:

    A longer hip extension moment arm at the hip joint creates greater hip extension joint torque and greater hip extension angular velocity. Greater hip extension angular velocity creates greater linear speed of the hip and all joints distal to the hip.

    A long hip flexion moment arm at the hip joint creates greater hip flexion joint torque and greater hip flexion angular velocity. Greater hip flexion angular velocity creates greater linear speed of the hip and all joints distal to the hip.

    This coordinated increase in joint linear speeds distal to the hip is the result of modifying two factors that speed the body up (hip extension moment arm and hip flexion moment arm) and results in greater linear speed for the road cyclist and a decrease in movement time.
  9. Real-World: Moment Arm
    The distance from the joint's axis of rotation to the line of pull of the muscle force.

    To increase the moment arm distance, you would need to move the line of pull of the muscle force further away from the joint's axis of rotation.

    One method for moving the line of pull of the muscle force would be to change the locations of the origin and insertion points for the muscle. This is not an option because it would be unethical to perform this type of surgery.

    The only way we can change the moment arm distance is by changing the angle of the joint.
  10. Theoretical: Mass
    *speed up*

    For the ankle mass box:

    Smaller body component and bicycle component mass distal to the ankle results in less angular inertia (i.e., less resistance to angular motion). This creates greater ankle plantar flexion and greater ankle dorsiflexion angular velocities. Greater ankle planter flexion and greater ankle dorsiflexion angular velocities create greater linear speed of the ankle and all joints distal to the ankle.

    This coordinated increase in joint linear speeds distal to the ankle is the result of modifying a factor that speeds the body up (body component and bicycle component mass distal to the ankle) and results in greater linear speed for the road cyclist and a decrease in movement time.

    For the knee mass box:

    Smaller body component and bicycle component mass distal to the knee results in less angular inertia (i.e., less resistance to angular motion). This creates greater knee extension and greater knee flexion angular velocities. Greater knee extension and greater knee flexion angular velocities create greater linear speed of the knee and all joints distal to the knee.

    This coordinated increase in joint linear speeds distal to the knee is the result of modifying a factor that speeds the body up (body component and bicycle component mass distal to the knee) and results in greater linear speed for the road cyclist and a decrease in movement time.

    For the hip mass box:

    Smaller body component and bicycle component mass distal to the hip results in less angular inertia (i.e., less resistance to angular motion). This creates greater hip extension and greater hip flexion angular velocities. Greater hip extension and greater hip flexion angular velocities create greater linear speed of the hip and all joints distal to the hip.

    This coordinated increase in joint linear speeds distal to the hip is the result of modifying a factor that speeds the body up (body component and bicycle component mass distal to the hip) and results in greater linear speed for the road cyclist and a decrease in movement time.
  11. Real-World: Mass
    Short-term for body component mass

    (1) wear the lightest clothing possible

    (2) wear the lightest shoes possible

    Short-term for bicycle mass

    (1) use a bicycle made of lightweight materials (e.g., carbon fiber or aluminum)

    (2) use light weight wheels

    (3) carry as little equipment as necessary

    Long-term for body component mass

    (1) lose fat mass
  12. Theoretical: Radius of Resistance
    For the ankle radius of resistance box:

    A shorter radius of resistance for the body component and bicycle component mass distal to the ankle results in less angular inertia (i.e., less resistance to angular motion) for the body component. This creates greater ankle plantar flexion and greater ankle dorsiflexion angular velocities. Greater ankle plantar flexion and greater ankle dorsiflexion angular velocities create greater linear speed of the ankle and all joints distal to the ankle.

    This coordinated increase in joint linear speeds distal to the ankle is the result of modifying a factor that speeds the body up (radius of resistance for the body component and bicycle component mass distal to the ankle) and results in greater linear speed for the road cyclist and a decrease in movement time.

    For the knee radius of resistance box:

    A shorter radius of resistance for the body component and bicycle component mass distal to the knee results in less angular inertia (i.e., less resistance to angular motion) for the body component. This will create greater knee extension and greater knee flexion angular velocities. Greater knee extension and greater knee flexion angular velocities creates greater linear speed of the knee and all joints distal to the knee.

    This coordinated increase in joint linear speeds distal to the knee is the result of modifying a factor that speeds the body up (radius of resistance for the body component and bicycle component mass distal to the knee) and results in greater linear speed for the road cyclist and a decrease in movement time.

    For the hip radius of resistance box:

    A shorter radius of resistance for the body component and bicycle component mass distal to the hip results in less angular inertia (i.e., less resistance to angular motion) for the body component. This will create greater hip extension and greater hip flexion angular velocities. Greater hip extension and greater hip flexion angular velocities creates greater linear speed of the hip and all joints distal to the hip.

    This coordinated increase in joint linear speeds distal to the hip is the result of modifying a factor that speeds the body up (radius of resistance for the body component and bicycle component mass distal to the hip) and results in greater linear speed for the road cyclist and a decrease in movement time.
  13. Real-World: Radius of Resistance
    The distance from the joint's axis of rotation to the center of mass of the body component.

    The length of the radius of resistance is determind by bone length and joint orientation. There is nothing we can do to decrease bone length. 

    However, similar to changing the moment arm distance, we can shorten the radius of resistance by changing the angles of the joints with the body component being rotated.

    Any change in a joint angle that brings a portion of the body component closer to the axis of rotation will shorten the radius of resistance.
  14. Theoretical: Application Time of Each Joint Torque
    For the ankle application time of joint torque box:

    A longer application time of the ankle plantar flexion joint torque will create greater ankle plantar flexion angular velocity. Greater ankle plantar flexion angular velocity creates greater linear speed of the ankle and all joints distal to the ankle.

    A longer application time of the ankle dorsiflexion joint torque will create greater ankle dorsiflexion angular velocity. Greater ankle dorsiflexion angular velocity creates greater linear speed of the ankle and all joints distal to the ankle.

    This coordinated increase in joint linear speeds distal to the ankle is the result of modifying a factor that speeds the body up (application time of ankle plantar flexion and ankle dorsiflexion torques) and results in greater linear speed for the road cyclist and a decrease in movement time.

    For the knee application time of joint torque box:

    A longer application time of the knee extension joint torque will create greater knee extension angular velocity. Greater knee extension angular velocity creates greater linear speed of the knee and all joints distal to the knee.

    A longer application time of the knee flexion joint torque will create greater knee flexion angular velocity. Greater knee flexion angular velocity creates greater linear speed of the knee and all joints distal to the knee.

    This coordinated increase in joint linear speeds distal to the knee is the result of modifying a factor that speeds the body up (application time of knee extension and knee flexion torques) and results in greater linear speed for the road cyclist and a decrease in movement time.

    For the hip application time of joint torque box:

    A longer application time of the hip extension joint torque will create greater hip extension angular velocity. Greater hip extension angular velocity creates greater linear speed of the hip and all joints distal to the hip.

    A longer application time of the hip flexion joint torque will create greater hip flexion angular velocity. Greater hip flexion angular velocity creates greater linear speed of the hip and all joints distal to the hip.

    This coordinated increase in joint linear speeds distal to the hip is the result of modifying a factor that speeds the body up (application time of hip extension and hip flexion torques) and results in greater linear speed for the road cyclist and a decrease in movement time.
  15. Real-World: Application Time of Each Joint Torque
    Each of these execution phases also serves as the preparation phase for the antagonistic joint torque (e.g., the execution phase for the concentric hip extension joint torque is also the preparation phase for the concentric hip flexion torque).

    Two execution phases must be performed at each joint:

    -Two concentric ankle torques (plantar flexion during the push down and dorsiflexion during the pull up)

    -Two concentric knee torques (extension during the push down and flexion during the pull up)

    -Two concentric hip torques (extension during the push down and flexion during the pull up)
  16. Theoretical: Radius of Rotation
    For the ankle radius of rotation box:

    A longer radius of rotation for the body component distal to the ankle joint creates greater linear speed of the ankle and all joints distal to the ankle.

    This increase in joint linear speeds distal to the ankle is the result of modifying a factor that speeds the body up (radius of rotation of the body component distal to the ankle) and results in greater linear speed for the road cyclist and a decrease in movement time.

    For the knee radius of rotation box:

    A longer radius of rotation for the body component distal to the knee joint creates greater linear speed of the knee and all joints distal to the knee.

    The increase in joint linear speeds distal to the knee is the result of modifying a factor that speeds the body up (radius of rotation of the body component distal to the knee) and results in greater linear speed for the road cyclist and a decrease in movement time. 

    For the hip radius of rotation box:

    A longer radius of rotation for the body component distal to the hip joint creates greater linear speed of the hip and all joints distal to the hip.

    This increase in joint linear speeds distal to the hip is the result of modifying a factor that speeds the body up (radius of rotation of the body component distal to the hip) and results in greater linear speed for the road cyclist and a decrease in movement time.
  17. Real-World: Radius of Rotation
    The distance from the joint's axis of rotation to the point of interest on the body component.

    The length of the radius of rotation is determined by bone length and joint orientation. There is nothing we can do to increase bone length.

    However, similar to changing the moment arm and the radius of resistance, we can change the radius of rotation by changing the angles of the joints within the body component being rotated. 

    Any change in a joint angle that rotates a portion of the body component farther from the axis of rotation will lengthen the radius of rotation.
  18. Theoretical: Fluid Density
    A decrease in fluid density would decrease the drag force on the body as it moves through the fluid. This would decrease the external forces slowing the body down and would decrease the sum of joint forces that the body must absorb.

    To decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slows the body down (fluid density) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.
  19. Real-World: Fluid Density
    During road cycling, the fluid you are moving through is air.

    There are three atmospheric conditions that would reduce fluid density:

    (1) higher altitude

    (2) lower humidity

    (3) warmer temperatures
  20. Theoretical: Coefficient of Drag
    A decrease in the coefficient of drag would decrease the drag force on the body as it moves through the fluid. This would decrease the external forces slowing the body down and would decrease the sum of joint forces that the body must absorb.

    The decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slow the body down (coefficient of drag) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.
  21. Real-World: Coefficient of Drag
    A measure of the surface friction between the air and the surfaces of the road cyclist and the bicycle as the road cyclist moves through the air.

    The coefficient of drag may be reduced by making the surface of the road cyclist and the bicycle smoother.

    For the road cyclist, this can be accomplished in 4 different ways:

    (1) cycling clothes must be made of materials that are extremely smooth

    (2) cycling clothes must be tight-fitting

    (3) the surface of the cyclist's shoes should be smooth

    (4) any uncovered areas of the body should have body hair removed

    For the bicycle, the surface of the bicycle should be clean. Any dirt on the bicycle would increase the roughness of the surface and the coefficient of drag.
  22. Theoretical: Area of Drag
    A decrease in the area of drag would reduce the drag force on the body as it moves through the fluid. This would decrease the external forces slowing the body down and would decrease the sum of joint forces that the body must absorb.

    The decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slows the body down (area of drag) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.
  23. Real-World: Area of Drag
    A measure of the area of turbulent air behind the road cyclist as the road cyclist moves through the air. 

    The are of drag may be reduced by making the are of turbulent air behind the road cyclist smaller.

    There are 4 primary mechanisms for reducing the area of turbulent air behind the road cyclist:

    (1) make the area of the road cyclist that collides with the air smaller

    To reduce the height and width of the road cyclist:

    • -hands of the road cyclist should rest on the handlebars in a manner that keeps the arms in front of the torso
    • -the torso should be flexed forward at the hips so that it is held close to the top of the bicycle frame

    (2) make the area of the bicycle and the wheels that collides with the air smaller

    -the bicycle and the wheels should be narrow

    (3) change the characteristics of the road cyclist to create better aerodynamics

    • -cyclist should wear an aerodynamic helmet
    • -if traveling 20 mph or greater, the helmet should have a roughened surface
    • -if traveling 20 mph or greater, the road cyclist should wear clothes designed to be aerodynamic

    (4) change the characteristics of the bicycle and the wheels to create a more aerodynamic bicycle

    • -if traveling 20 mph or greater, the rims of each wheel should have surfaces that have been roughened
    • -a solid wheel may be used to reduce the are of drag
    • -if traveling 20 mph or greater, the solid wheel should have a roughened surface
  24. Theoretical: Relative Velocity
    A decrease in relative velocity would decrease the drag force on the body as it moves through the fluid. This would decrease the external forces slowing the body down and would decrease the sum of joint forces that the body must absorb.

    The decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slows the body down (relative velocity) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.
  25. Real-World: Relative Velocity
    A measure of the speed and direction of the air that is colliding with your body.

    There are 2 approaches to reducing relative velocity.

    (1) road cycle on days when there is little or no wind

    -talk to someone about possibly adding more?

    (2) use a movement technique called "drafting"

    -following cyclist experiences smaller drag forces = energy efficiency
  26. Theoretical: Vertical Ground Reaction Force
    *slow down*

    A decrease in the vertical ground reaction force would decrease the friction force and decrease the external forces slowing the body down. This would decrease the sum of joint forces that the body must absorb.

    The decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slows the body down (vertical ground reaction force) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.
  27. Real-World: Vertical Ground Reaction Force
    There are 2 methods for reducing the magnitude of the vertical ground reaction force on the slowing down side of the model.

    (1) create a smaller body component mass

    • -short term: wearing the lightest clothing and shoes possible
    • -long term: changing body composition/loss of fat mass

    (2) create a smaller bicycle component mass by:

    • -using a bicycle made of light weight materials (e.g., carbon fiber or aluminum) and light weight wheels
    • -carry as little equipment as possible
  28. Theoretical: Coefficient of Friction
    *slow down*

    A decrease in the coefficient of friction would decrease the friction force and decrease the external forces slowing the body down. This would decrease the sum of joint forces that the body must absorb.

    The decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slows the body down (coefficient of friction) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.
  29. Real-World: Coefficient of Friction
    Friction is created between the tires and the ground. Although there are 2 tires on a bicycle, only one of the tires is part of the mechanism that speeds the bicycle up, the rear tire.

    The front tire should have the following characteristics compared to the rear tire:

    (1) the front tire should be made of harder materials than the rear tire

    (2) the front tires should have a smoother surface than the rear tire

    (3) the front tires should have higher air pressure than the rear tire
  30. Theoretical: Application Time of Each External Force
    A decrease in the application time of the external forces that slow the body down would decrease the sum of joint forces that the body must absorb.

    The decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slows the body down (application time of the external forces that slow the body down) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.
  31. Real-World: Application Time of Each External Force
    Decreasing the application time of each external force that is slowing the body down is a major mechanism for reducing the magnitude of the internal forces the body must absorb.

    The application time of the friction force starts when the wheels start to roll forward. It ends when the wheels stop rolling forward. Thus, there is no way to reduce the application time of the friction force.

    Similarly, the application time of the vertical ground cannot be reduced. As long as the wheels are on the ground, the ground reaction force will be applied to the wheels.

    For the drag force, there is also nothing that can be done to reduce the application time. If the bicycle is moving, a drag force will oppose the motion and slow the body down.
  32. Theoretical: Mass
    *slow down*

    An increase in the body's and the road cycle's mass would decrease the effectiveness of any external forces that slow the body down and result in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.
  33. Real-World: Mass
    Theoretically, increasing the mass would be an effective method to reduce how much you slow down. Unfortunately, a larger mass is more difficult to move quickly.

    There is a mass concept box on the speeding up side of the model; and the interpretation for that box was that the mass must be small if we want to effectively speed the body up. These two interpretations conflict.

    However, the logic should be easy to see. We need to get the body moving quickly each time we propel ourselves forward. This requires the mass be as small as we can make it. There is no way to simultaneously increase the mass so that we don't slow down as much.
  34. Theoretical: Distance
    A decrease in the distance traveled would result in a decrease in movement time.
  35. Real-World: Distance
    This concept should not be taken literally. It does not mean ride a shorter distance.

    Instead, its meaning is that if you are planning to ride for 15 miles, then only ride 15 miles. Do not tide 15.1, 15.5 or 16 miles. How is this accomplished?

    (1) when the road or path is curved, ride close to the curve

    (2) ride in a straight line from curve to curve

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