How to Determine the Size of Bicycle Pannier Bags

To determine the size of your bicycle panniers, you will need to take measurements and do some calculations. What you are looking for is the volume of the panniers. Volume is expressed in cubic measurements. In this case, you will use cubic inches. Often panniers will come with this information, but if they did not, it is relatively simple to figure out. Once you complete the computations, you can prepare a packing list for your bicycle trip.

Things You'll Need

  • Flexible measuring tape
  • Pencil
  • Paper
  • Calculator
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Instructions

  1. Measuring Rectangular Panniers

    • 1

      Mount the panniers onto the bicycle following the manufacturer's instructions. They will be easier to measure when attached instead of laying on a flat surface.

    • 2

      Many panniers are rectangular shaped receptacles so you will use the formula for computing the volume of a rectangle prism to determine the size of the panniers. The formula is: length x width x height. (See Section 2 if you have panniers shaped like trapezoids.)

    • 3

      Measure and record the inside length by measuring the from the front top edge to the back top edge.

    • 4

      Measure and record the inside width from the pannier's outside top edge to the pannier's inside (closest to the bike) top edge.

    • 5

      Measure and record the inside height from the pannier's outside top edge to the bottom edge. This will represent the depth of the pannier.

    • 6

      Multiple the measurements. For example, if the length is 12.5 inches, width is 6 inches and height is 15 inches, multiply 12.5 x 6 x 15. The answer is 1,125 cubic inches. Since the panniers are a pair, multiply 1,125 times two. Now you know your panniers are 2,250 cubic inches.

    • 7

      If you have front panniers, repeat the process to compute their volume.

    Measuring Irregularly Shaped Panniers

    • 8

      If your panniers are not rectangular, but are a an inverted trapezoid, compute the area of the outside surface then multiply by the wide of the bag to get the approximate volume of the bags. A trapezoid is a four-sided geometrical shape with two parallel sides and two that are not parallel. This description matches the shape of some panniers.

    • 9

      Take the measurements of the length, width and height. The parallel sides (top and bottom of the pannier) will be different lengths. The top length is a, the bottom length is b.

    • 10

      The formula for the area of a trapezoid is [a (top length) + b(bottom length)] x height x 1/2. For example, if the a (top length) is 12 inches, b (bottom length) is 10 inches and height is 15 inches, calculate (12 + 10) x 15 x 1/2 = 165 square inches.

    • 11

      To get the volume, multiply the area by the width. In this example, 165 x 6 (the width of the pannier) = 990 cubic inches is the volume of one pannier.

    • 12

      Since panniers are pairs, multiply 990 x 2. The volume of your panniers is 1,980 cubic inches. If you have front wheel panniers, you will need to repeat the process to calculate their volume.