There are quite a few commands in Rhino 3d. It will take a while to learn them. Perhaps it would be best to come up with a sketch, and then pick one part out, and start with that.
By all means, experiment with the 3D tools.
Part of the process is recognizing shapes. A simple tire more or less a taurus. A steel motorcycle frame is made from cylinders or pipes cut and fitted together. Nuts and bolts are hexagons and cylinders. Spokes are long cylinders. Engine cases are kind-of ellipses with a little node adjusting, which can be extruded. A handle-bar could be made using sweep 1, and a circle. The grip can be revolved with an outline to make a 3d one.
So, you recognize a shape in your motorcycle, and then draw it. It’s a process.
If only it were that easy….
