August 24, 2025
Description
Most city bikes have the ability to have a rack in the back of the bike. These tend to be very narrow and it is common that people strap on crates or bags to make these racks usable. Almost universally these are difficult to install and difficult to remove. I wanted to find a solution for a reusable and quick release for a milk crate. Version one of that design is here. This is great for groceries, farmer's markets, etc. but lacks the ability to move a pizza. So I developed a more universal system for strapping things to just about any rear bike rack.
Once constructed, this is a simple system. However, understanding it takes a little bit of work. I strongly suggest reading through the entire instruction set before buying materials or starting to print.
There are two different systems of attachment in this project that are built around two different spring loaded clips.
This system is highly adjustable, low profile and quick to print. However, it only really fits with the Pizza Plate, the Lowes milk crate, and 10-11mm cargo racks.
This is designed to take M6 hardware. If you are going to bolt the unit, you'll need two bolts, four nuts, and two washers per cleat.
I'd suggest that you want to print four of these, but can print as few as two to connect your cargo to the bike rack.
Taking the adjustable system and making it more general, this system is only limited by your imagination. These are designed to fit on anything that can hold a screw or a bolt. It is especially well suited for the Pizza Plate or wooden crates.
This is designed to take M4 hardware. If you are going to bolt on this unit, you'll need four bolts, eight washers, and four nuts/threaded inserts.
We will explore more options with how to mount this system in the following sections.
Designed to work with the Pizza Plate these accessories are for adding lights, feet, etc. to your Pizza Plate, and really making the system work for you!
This portion is a work in progress. Eventually I'll have accessories that fit in and around the slots and pilot holes to expand the functionality and usefulness of this whole system. I'll periodically edit this section with these expansion accessories.
While this might be named and inspired after the standard large pizza box from your typical American pizza places (Little Caesars, Pizza Hut, Dominos), it really is a platform to help you move whatever you want from point A to point B with your bike. The templates here are designed for a CNC, but can easily be cut out with hand tools and some patience.
This pizza plate has some strapping features to help you hold lots of things on your bike:
You first need to decide if you want the Adjustable System or the Universal System. If you do choose the Adjustable System, see the first version of the Bike Cargo System for more details. From here on out, the instructions will only cover the Universal System.
A cleat, the part with the latch, needs a minimum of 14mm in length to reach through the plastics.
In it's default configuration, without any spacers, it will fit a bar size of 5.75mm.
There is a 1mm spacer ("Cleat Spacer"), that can be adjusted in PrusaSlicer to fit any bar with a diameter greater than 6.75mm.
The “End Stop” has a minimum depth of 4mm.
There is also a 1mm spacer ("End Spacer") that can be adjusted in PrusaSlicer to fit any height required that is greater than or equal to 5mm.
From here on out, lets look at configuring the Universal System for a bar with diameter of 10mm as an example. (And please excuse my mixture of Imperial and Metric measurements. The American system of measurement is a mess, and I can't completely get away from Imperial measurements.)
I know that my rack's bars have a diameter of 10mm. This means I need a spacer, and can't just use the cleat alone. Since the cleat works with a 5.75mm bar:
10 - 5.75 = 4.25mm
I need a spacer that is 4.25mm thick. I need both the “End Spacer” and the “Cleat Spacer” to be the same width.
In order to get the proper size spacer, you'll need to scale the spacer in PrusaSlicer, but only in the Z direction. Since the default spacer are 1mm, you can either scale them with the overall measurements, or scale them by percentage, where every 100% increase over the default size would be 1mm. For our example I'd scale the Z measurement by 425%.
For this example, we are going to use a Pizza Plate. If you have a crate, wooden platform, or other object measure the width of that instead.
I bought a sheet of plywood that is nominally ¾" wood. Using a ruler, I noted that this was actually 18mm thick.
With the stackup of (Pizza Plate + Spacer + Cleat) I know that I need a bolt or screw that is no longer than (Pizza Plate + Spacer + Cleat)
18mm + 4.25mm + 14mm = 36.25mm
and is at least (Spacer + Cleat)
4.25mm + 14mm = 18.25mm
A 25mm bolt or screw would work well here for the “Cleat”. Using similar math, I find that I need a 10mm bolt or screw for the “End Stop”.
The minimum number of cleats is two. You'll need a pair either on the right and left side or the front and back sides.
I would strongly suggest that you use four, and space them as widely apart along the length of the rack as possible. The further these are apart, the more stable the system becomes.
For example, it would be strongly advised that you place a cleat at the two locations shown in green (left), and then mirrored to the other side of the bike for a total of four cleats.
If you are going to use only two cleats, place them either on the front and back sides (right), or mirrored at the yellow arrows (left).
You will also want to print an “End Stop” or two to keep the unit from moving forward and back. These will be placed next to cross members on the rack. See the blue arrows below.
You will need the following hardware for a single “Cleat”. Multiply this by each additional cleat.
You will need the following hardware for a single “End Stop”. Multiply this by each additional end stop.
I've had very good luck with PLA on bike projects, as long as it isn't left outdoors for extensive time. With that said, PETG here is a good choice.
I suggest this many perimeters so that all the force under the bolts/screws are over solid walls. This helps transfer the forces and allows for drilling the hole a bit larger if there is shrinkage or lopsided holes.
Press fit two washers into the “End Stop”.
There are two slots on the underside of the cleat that will fit an M4 nut. Press fit a single nut into each slot, making sure they bottom out.
Push the Plunger Latch into the teardrop hole in the center of the part.
Install the M4 x 25-30mm bolts to secure the Plunger Latch to the plastic “Cleat”.
Tighten these snugly, but don't over torque them, as you can pull the nuts through the plastics.
Press fit four washers in the top of the print, similar to what you did for the “End Stop”.
Measure out and screw or bolt the cleats and spacers on the Pizza Board. Here are some ideas for configurations.
Using three Cleats and no End Stops.
A Cleat with an End Stop.
Two Cleats and two End Stops, Centered on the rack.
For Cleats and two End Stops.
You can use threaded inserts like these (Amazon), use nuts and washers, or wood screws to attach your cleats to the Pizza Plate.
The plate and system is designed to accommodate large pizza boxes.
But this isn't everything it can do. Here are some examples:
With this system, you can strap a lot of different things to your bike in a lot of different ways. It's really up to you what you get to do, and where you get to use it. When you are done, it's a simple process to pull it off and set it aside.
If you liked this project, check out some of my other bike projects.
License:
Creative Commons — Attribution — Noncommercial — Share Alike
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NorseEngineer
