As a member of UC Berkeley Human Powered Vehicle, I was tasked with designing an ergonomic seat for our rider.
CAD Model
Design Considerations
When designing the seat, ergonomics were a top priority. Our research showed that the comfort and cycling performance of a recumbent trike depends on 3 primary angles – the body body configuration angle (BCA), the hip orientation angle (HOA), and the knee angle (KA). In a recumbent position, a BCA of 130 degrees, HOA of -5 degrees and a KA below 90 degrees maximizes comfort and power delivery while also keeping aerodynamic drag to a minimum.

I then took measurements of our intended driver (95th percentile male) as shown in the table below, and used these to scale the seat measurements accordingly. A lumbar support height of 11” with a back angle (BA) of 50 degrees was used to provide our driver with maximum support and comfort.
Measurement Definition | Dimension (Inches) |
Top of head to base of neck | 10 |
Shoulder to hip | 21 |
Hip to knee | 21 |
Knee to ankle | 18 |
Shoulder to wrist | 25 |
Width of shoulders | 22 |
Width of hips | 15 |
Overall Height | 72 |
I primarily used Fusion360 to CAD the seat, and used the surface modeling workspace to create the general shape of the seat using sweeps and cuts. I then used the thicken tool to add depth, and finally filleted sharp edges before importing the model into SolidWorks to use in the final assembly.