Copyright WWW.DBBP.COM | updated 3-May-2004

Because of the very large amount of questions I get about my Cadbike images, I will try to explain what they are and how I make them. I will start with a very general and short discription and gradually add more in-depth information.

How to make a CAD-bike:

How do I start designing a Cadbike?

I start with a "skeleton part". A skeleton part is a part that is built up entirely out of datum planes and datum axis ( and sometimes datum curves, datum points and datum coordinate systems)

Okay, and what are those?

Datum geometry is geometry that exists only for reference purposes and has no mass, no color, no material properties. It can also be switched on and off very easily.

The skeleton part contains the positions of front and rear wheel (the wheelbase) and also the angle of the steering head, the trail and the engine centerline (which is very important for determining the center of gravity and ground clearance). It is the first part in the assembly, and in the skeleton part I can already predict the handling characteristics of the bike. The picture below is of the skeleton part I used to design Cadbike #14:

Click for larger image

Usually I assemble the wheels, engine and gearbox next and then start sketching the frame.
In some cases I start with a frame from a previous project and play around with rake and stretch untill I get the look I want, and then try to get the trail right later....

To be continued....

Maybe these articles will inspire others to use their computers to design bikes,
it has a lot of advantages compared to pen and paper (did that) and it is fun to do.
The design can be viewed from any angle, many different parts can be tried before they are bought or made, the handling of the bike can be predicted exactly etc....
Think about it, people are building $200.000 bikes without even making a decent drawing, would you build a $200.000 house without a drawing?????