I would like to share with you a project that I have been working on since 2017. I posted this story on a French framebuilding forum before, but it’s basically dead. I think this is a better place to get your valuable feedback and advice on such a project. The topic has already been addressed with other amazing cargo bike projects, so why not bring it here?
Like many people, I am fascinated by hub centre steering mechanisms. Despite the high manufacturing cost, I believe that this new steering paradigm can transform how we think about steering and suspension when designing a cargo bike.
I came up with this project while designing a cargo bike, which is currently on hold due to some time management difficulties. For now, I am mainly focusing on the steering hub and suspension. For context, here is a picture of an early conceptual version of the project as a whole.
Before providing a detailed description of the project and its various issues, here are some renders of the CAD model and pictures of my current progress.
I also find such a concept incredibly interesting. I’ve often stumbled across such solutions online, which are very challenging to implement due to the complex mechanical manufacturing process. Your concept looks very interesting, as it consists of a complete set consisting of the hub, brake caliper mount, and steering mechanism. If the matching geometry for the fork mount were published, it would certainly be easier for those wanting to build their own. A commercially available hub set would be a dream
Yes of course. We got in touch when he was working on his first iteration. He used my work I published on grabcad as a base to make his own. It look like he made a lot of changes, don’t know if it still share similarities though.
You are reading in my mind ! In a perfect world I would like to develop a complete technical solution to sell. Kind of setting up a new standard for Hub center Steering for cargobikes. For now Elian Steering already do this and they are desiging a far more integrated hydraulic steering mechanism than my proposal. Can’t wait to know a little bit more about what they are up to.
Yes, that hydraulic steering looks amazing for a cargo bike. Eliminating the need for a long headtube could give so much room rearward, beneath the riders’s hands, and in front of the feet.
Right ! Of course I’ve been following his adventure. I’ve always been impressed by how quickly he started production. I’m aiming for a more compact form factor for my hub, but his design with the standard headset integration is definitely working well. And the fact that he designed the the whole cargobike with it… respect.
It depends on the problem you are trying to solve. From my point of view, it’s clearly a good design for managing the cargo area of a long-john type cargobike, but it certainly adds to the complexity and cost.
This mechanism is over 100 years old, and people regularly dive into this special kenematic, bringing improvements and innovations to it each time. I don’t think humanity has figured out yet whether it solves anything. We need to work on it more !
Regarding the turning radius/steering angle, my prototype has a 35° left/right angle, but Elian’s hub is better with a 41° angle. This could be improved by reducing the width of the hub and increasing the inner hub diameter. Achieving this balance is difficult if you want to stick with a compact hub form factor. However, I believe I can improve my design in this respect without compromising the existing design too much.
Yes, it’s a zero-offset design, but you can improve the trail by adjusting the caster angle of the entire assembly.
The following animations do not clearly illustrate the caster angle issue, but they can provide some insight into the kinematics of the entire assembly.
