Bike-Portable Shopping Cart





Introduction: Bike-Portable Shopping Cart

This project shows a way to bring the groceries from the cash desk in the supermarket into the house. To do so, I designed a stable shopping cart that can be carried on the rear rack of a bicycle. The wheels can be folded down to use the cart at standing height. Beside shopping cart it can also be used as a child stroller with room to store things. No modification at the bike is necessary to use this cart in a simple and versatile way. Simple, because you can easily take the cart on and off the bike. Versatile, because you can think-up many applications. The wheels are nearly 20 cm or 8 inch, so you can drve with ease on streets and sidewalks. Also low thresholds are no problem, that different from the usual shopping cart. The container is made from 9 mm or 0,35 inch thick multiplex board, glue'd and nailed together. All parts of the cart you can buy at the local diy market. I used the castors of an old  rollator. The weight of the cart is 11Kg or 24,25 pound. The volume is 50 liter or 13.2 gallon. A building plan, an instruction video and many photo's are making this project easy to replicate.
                                                                           The movie


Step 1: Building Material

I like working with wood. It fits in well with this project. You can buy it in the local DIY shop and you can edit with common tools. I took a 61cm by 122cm or 2x4 foot multiplex board. See picture 3. Birchwood 8mm or 0.31 Inch at the outside and the stronger 9mm or 0.35 inch standard multiplex at the inside. See picture 4. Now we can start drawing the sizes on the board.

Step 2: Measuring, Drawing, Cutting and Sanding.

A variable dimension is the width of the rear rack. The upper rack size is different from the lower part, where the rack is connected to the frame. We have to use the lower size. We have to calculate this when drawing the pieces on the board. An other size is the width of the saw cut. When drawing the sizes on the board we have to calculate this width. In my case it was 2.3mm for the circle saw. After cutting the pieces of the box the sanding machine is doing good work. The last picture shows the exploded view of the box.

Step 3: Glue, Nails and Screws Makes It All Together

The whole box is glued and nailed. The nails are 1.6 x 25mm or 0,06 Inch x 0.1 inch. Take care, the placing of the nails is critical because the width of the board. The top border is connected with screws, see  picture 5 and 6. The box is now ready for wheels.

Step 4: Legholders and Handlebar

When the box is ready we can make the four legholders. That are the side panels where the folding legs rotate around their axis. A PVC tube is used as spacer tube. See picture 4. Now we can also make the telescopic handle bar of the cart. The outer tube is connected to the cart by brackets. There is a lock pin to fix the handlebar in the upper and lower position. See picture 5 and 6. I made 2 handles on both sides of the box to make it easy to carry.

Step 5: Connecting the Castors to the Legs

To connect the castor to the leg we have to bend an iron strip in a U shape. Before that, we have to drill the central hole of 12mm or 0.47 inch. Picture 2 shows an easy way to bend the strip with a block of wood. I made a cut with circular saw where the strip fits in. Picture 4 shows the 12mm or 0.47inch wired rod. I had to cut of a piece of 55mm or 2.1inch for the swivel axis of the castor. See picture 5. The construction drawing shows the parts with sizes. The legs are made from pine wood; the section is 40 x 44mm or 1.57 x 1.73inch.

Step 6: Big and Small Castors. Painting the Finished Cart.

The big castors are from an old rollator. They have ball bearings to rotate and to swivel. These wheels roll very light. They have soft rubber tyres, perfect for the shopper cart. At the other end of the leg we see the small castors, handy when the cart is in the low position. Now you can see the folding legs secured by a lock pin. The same pin is for locking the upper and lower position of the wheels. I couldn't make it more simple and easy to use. After that all is put in place we can start the painting job. Before that it's good sanding the whole cart for the last time. I was using transparant stain for the box and a grey color for the legs and the legholders. I made also letters on a green painted background strip.

Step 7: The Eco Shopper in Use

The last pictures speak for themselves. Picture 4 shows how the legs come down. The cart is still on the rear rack of the bike. First taking out the lock pin. Than the legs are going down. Now the lock pin is going in to fix the high position. Now you can easy roll the cart away from the rear rack.
Conclusion: To make a prototype is not a rapid job. Finding the right sizes is the main thing. The folding system of the legs was the most time consuming part. The legs are standing slightly forward and backward in order increase the stability. I made strips on the box to fix the castors in the high position. To keep them flat agains the box. The volume of the cart is enough to contain food for 2 persons, shopping once a week in the supermarket. Everyone is free increase the volume of the shopper cart by making the box wider or higher. My wife can handle the weight with ease. All in all, it was a challenge to find a new way to shop without using my car. People turn their head, seeing a strange object on the back of my bike. Using a bicycle is always eco - friendly.



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Please be positive and constructive.




I'm sorry, but this seems like a solution in search of a problem. I think that a homemade bike trailer ote even saddlebags would be more effective for transport on the road and a cheap, folding wire basket would work to get your purchases into the house. Yeah, you'd have to transfer your goodies from the trailer to the basket, but how much stuff will you actually be carrying by bicycle?

You would be surprised at how much groceries I carried on the back of a bike using a clothes basket and is much better

Bike rack holder

Fantastic idea. How does the cart secure to the bike rack?

How does the cart lock onto the bike rack?

By weight and tight fit stays the cart onto the bike rack. You can use a small chain lock by making a hole in the frontside of the 'bridge' of the cart and attach this to the rack or saddle.

Very nice design, I absolutely love this. The only problem I would have is that I would require a cover as the roads are really bumpy around here and groceries would go flying (Yes, even an low speeds). I would also incorporate LED lights into it, and paint it a florescent color (I like florescent green) , so that when I add it to the bike it increased visibility. Currently I have a bike trailer and two baskets on my bike, which are a pain to carry to the store, though I can haul a lot on the trailer.

Nice that you mention your current way of shopping. My question was how to minimalize the times of taking the grosseries in the hands. The optimal score is from the store shelf in the cart and from the cart in the fridge or store space at home. So, no carrying of bags. Problem is the check out, there I have to take the goods once again in my hands. Supermarkets want only their own "open" shopping carts behind the cash desk.


Fantastic project! I am planning to build this. One question though, bear with me if it sounds dumb, but how do you lock the box onto the bike rack? Is it just the weight that holds it in place or is there something I missed? Love this and many thanks!

Thank you, that you appreciate this project. The weight holds the cart in place. To lock the box you can attach a piece of wood onder the "bridge" that fits between the crossbars of the rack,

Locking system to bike.

I don'tsee how this great idea locks to the bake rack.