Carrying mountain bikes on cars
While the rear-mounted bike racks with two horizontal bars have been around for a long time, I don't enjoy the process of playing bike tetris to keep the frames and forks from being covered in scratches. Yes, I am OCD.
The racks that hang bikes beside each other seem like a better design. These racks hold the bikes vertically. They're quite common now, from one-off builds to industry brands like Yakima at $1,300 NZD and cottage brands like Real Rack at $1,700 NZD. I would like one, but I don't want to spend that much, so I'm thinking about building one, because as we all know our time is free 😆
Like the existing racks, I want my rack to support 6 bikes. I have an old car, so unlike them, I want mine to mount to a box fitting AND a standard tow ball. So, I booted up AutoDesk Inventor and started inventing. This is what came out:
The design was inspired by copied from the Lolo Racks design. They don't ship to New Zealand, and their patents are US-only, so I assume this isn't illegal. Like American trucks, I think their design is too large and heavy, so I made it lighter.
The hooks on the upper beam are laser cut and then folded. I did an FEA analysis to minimize weight, but this is is only as good as my estimation of the shock or inertia load. Given the consequences of a highway accident, I want to take measurements with a load cell before I remove any more material.
The tow-ball attachment clamps the car's towball bracket from above and below.
I built a prototype in 2017. This is what it looks like in the real world:
In hindsight, there's a lot I'd like to improve. I drew the mount so that the car's departure angle wouldn't be affected. I don't think this is necessary. Most of the use cases for a rack like this, given the weight of the bikes, will be on paved roads, rather than sketchy riverbanks or other off-road terrain.
The lower triangle is also too complex. I think this can be two laser cut plates. I'm still thinking about a way to make the angle of the column infinitely adjustable while still being strong enough.