Once upon a time, far north in Scandinavia, a Norwegian man wanted his children to start experiencing the little adventures of daily life and holidays at a young age. That signalled the start of Nordic Cab. His legacy and founding principles are designed and administered into each and every Nordic Cab product to this day.
Nordic Cab were approached by Merdia GMBH to produce a mid priced double trailer. Pivot were given the task to design and devlop this model that would receive the name Active.
The task was to create a mid priced lightweight trailer with space for 2 children. We wanted to pack the trailer with as many features and performance as possible so with the goal of mid price and lightweight it was a good challenge.
Looking to other markets we extracted inspiration from the car seat and pram industry. Existing bike trailers have 2 identical size/ergonomic formed seats, this is not the case with the occupants. There is usually a 1-3 year gap between siblings, with younger occupants it is desirable to have the calf's supported making for a longer seat base where as the older sibling the seat should end before the knee. The other benefit of this configuration is when the older sibling starts to ride their own bike the occupant left has a larger seat.
We saw the opportunity to introduce a engineered suspension system. We analyzed systems on the market and the geometry/performance was more of a marketing point than feature. The system we developed is independent meaning both wheels move freely up and down without affecting each other. The performance has also taken into account the load cases the trailer will experience meaning it will perform over a wide range of scenarios. We also managed to acheive a level of progressiveness, this is the effect of the suspension getting stiffer when it moves through its travel range.
Most other trailers on the market when folded are long and thus make bad use of space in a car boot. We held strict control over the folded foot print so that it is possible to lay flat in a car boot.
The active features occupant protection through the means of a roll bar and the hips of the occupants are below the main frame. So in the event of a roll over or impact the occupants are well protected.
Our starting point was to define the 3D models of the occupants, We used the same standards as in car seats. This approach would ensure we developed a product around the users.
once we were happy with the proportions meeting the desired spec points such as total width and head room we then started to within the limits design the trailer. Using real time rendering were are able to adjust colours and forms until the desired result was achieved.
To develop the suspension system on the active we used mechanics to calculate the travel and performance under load cases. We designed in an element of sag so the wheel will always be able to drop to maintain contact with the ground. Experimenting with geometry we managed to also introduce progressive behavior, the angle that pushes on the shock gets smaller with its movement requiring more force for the same travel as the suspension goes through its range. Finite element analysis was used to design a system that was as light and stiff as possible, to get the suspension independent means an off center load, the result is the need for high torsional stiffness. The suspension system was prototyped and tested before being optimized by the producer for die casting.
The seats were a large part of the development of the active. We designed them around the average size users taking into consideration strap height, leg support, hip width and sitting angles. The result is a ergonomic bucket seat lowering the center of gravity, the design of it being lowered also utilizes the lower frame of the trailer a side impact protection.