Instructables

Bike-Portable Shopping Cart

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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

            
 
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Step 1: Building material

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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.

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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

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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

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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.
sLsM9 months ago
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!
IamWe you are a person of great foresight and whimsy I loved your Instructables for the bubbles! Ai 51 I still love to blow and run after bubbles! One of life's simple joys!!
Great and super creative idea! This could be the next best thing after reusable totes as far as being a Conscientious Consumer !!!!
Now if we Americans could just get off our tushies and bike places, we might not remain the World's Most Obese and Resource Wasteful Country!!
skorpijon9 months ago
Awesome, I love it! I will make it. Thank you ;)
tstupple9 months ago
Dit is een briljant idee, echt iets dat ik van plan op het bouwen, om te helpen met de boodschap
kishida9 months ago
I like the way it jsimply rolls on and off the bike rack and that you don't need to keep on moving groceries in and out of different places. You've inspired me to make my own. I might try to use lighter materials, maybe tent parts (tent poles, tent fabric, baby buggy wheels). Thanks, Ken.
areyouolsen9 months ago
Awesome idea! This really is a creative way to solve shopping on your bike & having to constantly pack/repack everything. Fantastic!
AJMansfield9 months ago
"0,35 inch" nobody uses decimal inches. That's as much baloney as saying 5 3/16 cm.  Totally bogus, right? Besides there is no such thing as 0.35 inch multiplex. The correct nominal value for the equivalent component is 3/8". Please read this pdf explaining the proper way to do this sort of conversion.
Although, reading the rest of it, you actually did a pretty good job with the conversions for most of it.
boempa9 months ago
Geweldig! Geen fietstassen meer nodig, je hebt gelijk je boodschappenkar bij je.
Love this build, so pratical for everyday grocerie shopping!
catsco9 months ago
Brilliant!
flyingpuppy9 months ago
Love the collapsing wheels!
DutchJean9 months ago
Fantastisch! Absolutely wonderful! You should sell these. For unhandy folks like me.
This is absolutely fantastic, honestly I can't think of anything better to say then that about it. I love how it rolls up to the back of the bike locks down & then off you go. I really hope you win the contest.
infernisdiem9 months ago
Ok, when I first saw she was "dragging" it across the ground I was going to say wow this is durable, then saw the little wheels at the end, this is a very good looking bike rack/shopping cart, A+ :D
redfoxtrystman10 months ago
First thing that came to mind is johnny 5 the robot off of short sercut. Sorry about the spelling and if no one thinks the same. It might be because I'm going on an hr of sleep. Our cat was in labor all night. So far 2 still born and one healthy boy. I think one to go
audreyobscura10 months ago
You should enter this project into the Bikes and Wheels Contest!
artlife10 months ago
Fantastic! This is a great design.
HelmutHound10 months ago
You should start selling these in stores and bike shops!
Yard Sale Dale10 months ago
Nicely done. Really, it's deluxe! I like the idea of using your own cart. Are most stores allowing that? I don't see any problem with it unless the cart is really big or has something that damages the floor. Yours looks smaller than a standard cart and has good wheels. I like the trailers made from buggies (the plastic ones are far lighter!) or modified kid trailers. Mine can just be pushed or pulled on its 2 bicycle tires (poly foam), and hooked back to the bike when done shopping.
saosport10 months ago
great idea
ynze10 months ago
Great cart, Berto, and a great instructable too!
J-Five10 months ago
Genius, pure genius!!!
rimar200010 months ago
WOW, this cart is a dream. You would make it to market!
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