Make a backpack for cycling after identifying various requirements and issues related to carrying this accessory while riding.

Character:

Either the construction or the material used makes the bag sweat free.

Appropriate choice of material and fitting components to reduce weight to a range of 1.25 to 1.5 kg. Colour and finish of enhance visibility for safe riding in traffic and night time.

Easily washable as the bag tends to attract lot of dust depending on the place of ride.

Form of bag to be aerodynamic to avoid drag while riding. This would also add to to sporty feel of pace and dynamism to the product. Lining fabric for the interior. Eva foam could be combined with fabric to retain form.

Web fabric with 6mm foam to be used in shoulder straps. Thermo-formed PC sheet could be used in parts to make the bag sturdy.

Specification:
3 compartments, 1 large to accommodate the voluminous items like water bottle, juice, clothes.

1 compartment for tools are sweat clothes and a small compartment for wallets, keys and phones. Rain cover for protection of bag and contents during rain. Provision to hold helmet in the bag so as to carry it when not riding.

Carrying items:

Water bottle/juice Food items Pair of clothes Basic tools/spare tube Torch/camera/charger Cell phone/keys/wallet

Step 1: Ideate.. Draw

This might be the crucial step. Sketch and doodle as many ideas and concepts as you can. Make ideas that solve problems and excite you.

Quality of the sketches are not important, it's the idea that matters. Do not hesitate to draw even if you can't make fancy sketches.

Step 2: Select

Main problems with the backpack are sweat on back and weight. Cyclists tend to sweat a lot while riding. Proper sports wear lets the sweat evaporate to make the rider thermally comfortable.

Backpack on the back limits the ventilation on the back resulting in excessive sweating.

I chose to solve this problem by minimizing the contact area by pushing the bag away from the back.

This could be achieved in a number of ways, one would be to make the rear side hard and form it in such a way there is space between the back and the bag. This also makes the bag sturdy.

Step 3: Simulate and Evaluate

Ideas generally seem to work on paper. They have to be evaluated using some cheap and quick means. The idea behind making cheap and quick mock-ups is that you don't waste time and money in refining aesthetics.

Its better if the mock-ups are dirty and rickety. This lets you modify and evolve them without worrying about the looks.

corrugated sheet: Make the shape in styrofoam to check the space for air movement

Polyurethane foam: Make the form in PU foam to evaluate the aesthetics.

CAD model: model it in cad for further designing and testing.

Step 4: Design

Internal compartments were segregated based on 'categorizing the items' carried.

Clothes and hydration pack is contained in the same compartment with a separate pouch for the former.

Used clothes could be isolated from the fresh ones through a fabric partition. The fabric partition could be removed when not in use and a larger compartment is required.

Elastic snap buckles are designed for holding the helmet.

Separate section for electronics gadgets. Quick access pockets for phones and maps are provided at the outermost flap. Rain cover is contained at the back of the helmet flap.

Step 5: Detail

The higher the attention to detail the richer will be product experience.

The hard back plate is made of polycarbonate to which the shoulder straps are riveted. The rivets are concealed by the foam backing which acts as cushion for the back.

The hard(polycarbonate) and soft(fabric) components of the bag are fused with a reverse zipper.

A PVC beading runs along the edge of polycarbonate back plate defining its edge and also houses the zipper.

The edge of the fabric is defined by PVC piping along which the other end of the zipper is stitched.

Closing the zipper fuses the hard and soft components.

Step 6: Make It: Vacuum Forming

polycarbonate back plate:

This involves 3 steps:

1) Mold making: A mold is made with MDF(mild density fibre) to the shape of the back plate. MDF boards are stuck together to form a block. Later with the drawings as reference they are carved to shape by hand. The same could be achieved by CNC milling.

2) Vacuum forming: A sheet of polycarbonate is vacuum formed with the MDF mold. This gives the basic shape to the backplate.

3) Trimming: The excess material of the vacuum formed sheet is trimmed giving the back plate the final shape

Step 7: Make It: Paterning

In order to make the fabric take a desired form they have to be cut and stitched in specific shapes.

This involves 2 stages.

1) Styrofoam mold: The desired form of the fabric(bag's shape) is first made using a Styrofoam block. Masking tape is stuck over the block and the stitching lines are marked on it.

At this point you will have a styrofoam that looks like a the bag and has the stitch lines marked on a masking tape.

2) Developing the surface: The masking tape is cut along the markings and pasted on required fabric. Outline of the masking tape is sketched on the fabric and later cut.

This leaves with pieces of fabric when sticthed will give the desired form.

Step 8: Make It: Stitching

The cut fabric is stitched together along with zippers and buckles as per the design.

At this stage the inside of the bag will have naked stitches this has to be concealed using the lining cloth.

The shoulder straps are also done similarly with foam filling for cushion.

Step 9: Correction

If you have the luxury of making another bag, the first bag might not meet your expectations. You would want to make a few changes and refine it further so as to nail the usability and aesthetics.

Make the final backpack with these refinements.