The Double Decker Mini Velo Cargo Bike

At the encouragement of a few friends, I’m going to try to document my ideas here into something hopefully coherent as I try to build a bike. I don’t have the funds to build this bike just yet, so I’ll instead spend my time figuring out all the details and possible pitfalls digitally. Hope you’ll enjoy following along.

So with that said, here are my thoughts.

I want to design and build a cargo bike. I’ve had them on my mind for a few years and it would be so nice to eliminate a few more car trips. I already bike to work quite often so grocery runs would be fun. I also like to make “fun” bikes that aren’t so cookie cutter. Since I work in bicycle design, most of what I design is mass produced and I feel sometimes lacks a personalized touch and character. (but that’s a discussion for a different day.) I had originally thought of using a full size shopping cart as the size constraint of the carrying base of an extended wheelbase cargo bike. I.E. Bullit. But, I don’t have a lot of room for another bike in my shed, so I was thinking of ways to make a smaller cargo bike. I like the idea of utilizing shopping carts since there are several discarded carts lying around I could salvage. I had an epiphany. What if I could use one of the small double decker shopping carts as the base and create a sort of combination of a Bullit and an Omnium cargo bike. Of course it would have to have a small front wheel, but the wheelbase could be made shorter by splitting up the cargo areas into two separate locations. It wouldn’t be able to carry huge items, but that’s not my goal. With a small rear wheel to match the front, the overall size of the bike could be minimized. So I got to sketching my ideas out.


*not drawn to scale or with accurate angles

It would still need a linkage driven fork, but the linkage is straighter like the omnium and probably easier to make. The other nice thing is that I can maybe use a normal frame jig to build parts of this bike. I’ll have to try to work out some other details once I start building this up in CAD. I’ve never built a mini velo or a cargo bike so if anyone has any input on geometry, I’m all ears. I’m open to any ideas or suggestions on how to make this better.

I know my sketch doesn’t show fenders but I hate drawing circles so I just left them out.

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If it helps in anyway, Phil Vandelay recently did a video that covers his cable steering and I think it’s a good design. It’s got some custom lathe work to create the steerer tube connections, but it’s pretty well done.

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Funnily enough, I watched those videos just yesterday(of the day before). Maybe that’s part of why I thought it a good idea to document my process. I’m a little jealous of his shop space. I guess I should have added that I am a little limited in use of tools. So no bent tubes, or lathes. His steering mechanism is quite simple though. But still a little more complex than I want to tackle for this one.

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I once designed and built a prototype for a bike with similar topography. The Downtube needs to be massive (50mm or even more) and the steering tube/downtube junction needs some serious reinforcement if you don’t want it to ride like a wet noodle and crack after a few braking maneuvres…

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@Luniz82 That’s a very good insight. Do you think connecting the steering tubes together with an additional tube would increase the stiffness? I would love to keep the tube diameters down to 38.1mm or less to match the size of the Bottom Bracket shell. Like this?

I put a little bit of time into CAD and downloaded some shopping cart files that I’ll rebuild once I get my hands on the final pieces. These will serve as placeholders for now. As far as Geometry goes, I based the rear end on what I would do for a 29" wheel gravel bike rear end. Similar bottom bracket height and Chainstay length (horizontal). I think the wheelbase is around 1600mm. I really need to get the correct size shopping carts so that I can minimize the wheelbase as much as possible. The wheels pictured are 20x2.4" but I guess I could go smaller if I was using fenders. I’ll get to figuring out the design of the fork next I think.

I wonder how short I can go until toe overlap with the basket becomes an issue.

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This will work fine, triangulation is your friend :wink:

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Looks cool!

That lower rack basket looks very close to the ground. Thinking outside the box, could you put it on a linkage so that the basket lowers when you park and doubles up as a kickstand?

I’ve built 6 small cargobikes over the last few years, including some fairly whacky ones, there’s lots of iteration to look at if you scroll back in here:
https://www.instagram.com/woofcustommetal/

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I just noticed some old comments I had made on your instagram. I didn’t realize you changed your username. Those are some fantastic bikes you’ve been making. I also love the idea of a basket/kickstand. I had been struggling thinking of how to make a kickstand and how to make the baskets attach/detach so this might kill two birds with one stone. I’ll have to get the actual shopping baskets in hand so I can measure things out and see if it’s even possible.

What about a mini-velo cargo-bike with 20" wheels? One mini-shopping-cart basket at the front, another at the rear. Some examples…


(from James Black : The New Cycle Truck)

-Jim G

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Here is another one from France: Le petit porteur

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Those are absolutely delicious. I like them, but I’m also just stubborn and want to do this the dumb way. I do love the twin tubes on the first one. I may have to incorporate that idea into my design. The rack mounting system is interesting. I’ve been struggling with rack/basket mounting.

Thanks @Johannes for that one as well. All the inspiration is helpful.

I’ve been thinking more about this over the weekend. I think I may need to consider building the baskets myself. I like the idea of salvaged shopping cart repurposing, but I’m concerned about their strength and mounting. I doubt I will find any reason to remove the baskets from the frame so I might as well attach them permanently. I don’t live somewhere where storing this bike would benefit from a narrower footprint. And as @Woofcustommetal pointed out, the lower basket could double up as a kickstand support if designed properly. This would be easier if the basket were sturdy.

I put some more time into CAD. I made the baskets a little smaller and built the file so that the basket size is a driving dimension that affects the wheelbase and front center. So when I finally decide how to make the baskets it will update with whatever size I decide and I can keep working on designing the other parts of the bike until then.


I do like the matching shape of the downtube angle and the basket upper line and how the baskets are just reversed. I think I’ll try to build the linkage for the steering next. (after inserting the headsets first)

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I’ve been thinking and would love to hear anyones thoughts. What if I make this an E-Bike? I have access to Shimano motors and batteries and stuff through work. Would it be that much of a benefit to have a motor for something like this? I’m not a big fan of E-Bikes, but I also want to make this bike super practical and useful. I could probably make the motor mount out of sheet metal with the cutting and bending done by Send Cut Send. I’m just not sure if it’s worth the hassle over just making this a normal bike. I’d love to hear anyones thoughts that has had a cargo bike, E-bike or not.



I also tooled around with trying to make the wheelbase shorter and I think I’m just going to make my own baskets. That way I can determine the size and shape and make the mounting system better. Especially since the lower basket is going to need a built in fender or something.

I’ve had cargo bikes on my mind for the past month or so too. I really like your idea to use shopping cart baskets (whether they’re taken from a cart or made by you, I still think its a cool idea).

I’m not sure what the terrain is like down where you are, but I assume it’s probably pretty similar to SLC in that there aren’t hills until there are. I live on one of those hills, and I think if I were to make a cargo bike that is an effective car replacement and doesn’t introduce a new burden or inconvenience, it would need a motor. Yeah, I’m kinda ambivalent about e bikes too, but it just makes more sense to me for a cargo bike to have a motor given the hills and how spread out things are in the middle US.

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Yeah. I’m afraid that’s just how it’s gonna be.
On that note, does anyone have the CAD for the shimano e8000 motor cabinet?

So I just did some eyeball CAD and hopefully that’ll be close enough until I can get my hands on the actual Motor Cabinet.

But I also was playing around with chainstay length. My thinking is that since I’m creating a long wheelbase carbo bike built around 20x2.4" wheels, I can shorten the rear center since there isn’t any risk or wheelie-ing over. I’ve kept the seat tube angle reasonable so the riding position isn’t compromised, but how short would be too short? Right now this image shows 360mm horizontal. I’ve kept a narrow chainline and clearance for a 44T chainring and the chain stays will only require a little dimpling.
Any Thoughts?

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I wouldn’t go too short on the rear end. You want to think about front/rear balacnce. Linkage steering already means there’s so much weight over the rear wheel so you could easily end up a little low on traction up front, especailly when unloaded, which may give you washy steering. I ride an Omnium Mini-Max which has a full size (29") rear wheel to go with the 20" up front and 460mm stays and it really handles great, loaded or not. Even a Mini-Velo like the VO Neutrino has 380-400 mm stays and that’s with a standard front end. So yeah, I would say 400 min seems to make sense for the design you’re workin on. But hey maybe try 360 mm stays then let us know how it rides!

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Don’t want hijack your thread just thought I would chime in. I’m doing something similar. A smallish cargo bike with a 20” front wheel and 26” rear wheel. Here is where I’m at

It’s an experiment and a way to practice welding. The downtube and extension tubes are 1.625” .058. The headtubes are 46mm. A milk crate will be mounted to the front. I suspect it will ride like a wet noodle and snap at the headtube but I’m forging on anyway.

Also plan on making it electric. I thought of using a Shimano or Bosch cabinet but the cost is out of my price range. I plan on using a Bafang BBSHD instead. No experience with this mid drive but it’s been around for more than a minute and many people are happy with them. If you use the Shimano cabinet you are stuck with that system. Using a regular BB gives you way more flexibility. Have a look at the kit type mid drives that you can mount to a regular bike. You might decide that the electric thing is not for you and want to make it a regular pedal bike instead.

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@bushtrucker you bring up some good points. I was super focused on minimising the wheelbase at any cost and I figured the short rear center was ok since it has a long front center. I don’t know how much riding it’ll get unloaded but I guess if I use it for shopping, half the trip is empty, and the other half is full. lol
I also forgot that super short chainstays are hard on drivetrains. I don’t want to have a crappy shifting due to harsh chain angles. I’ll probably do 400. Makes the chainstay dimples smaller too.

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@TDotBikes dont fret at all. This can just be the weird cargo bike thread. Lol

My reasoning for shimano is my job. I’ve got sample motors and test stuff I can “borrow” (steal) I’m honestly not a huge fan of e-bikes but that’s mostly due to my mountain bike background. I don’t like riding them out on the trails but I also ride a 150mm hardtail right now.
I have some experience with hub drive e-bikes and mid drive and I like the experience on a mid drive better. I do wish there was an easy way to convert back to a regular bike. Though if it comes to that, I’ll probably just sell the bike and build something new.

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That’s great! I would rather use a Shimano Ebike system but I can’t justify the cost since I’m only playing around.

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