• The backpack hangs off the back so its acceleration is due to gravity
• Mass backpack = 1Kg
• F = 1Kg/10m/sec2
• Total Force = 10N

Panniers:

• Panniers hang off the back of the bike rack also its acceleration is due to gravity
• The Mass of Rack and Panniers = 2Kg
• F = 2Kg X 10m/sec2
• Total Force = 20N

Bob Trailer

• Trailers have the Force of Weight + the Force of Tension
• The Mass of the Bob trailer = 0.7 Kg
• Fw = 0.7Kg x 10m/sec2 = 7N
• Ft = 0.7 Kg x 2m/sec2 = 4.5N
• Fw + Ft = 11.5N
• Total Force = 11.5N

For the most efficient ride use a Bob trailer