Bicycle Design

I do my design work for all my projects in Draftsight. It's a CAD package like Autocad but it's free to download for personal use. As I liked riding my Giant Defy1, that was to be my template. I used it as a background reference image and began to draw. I also had a table of all the frame angles and lengths of the Giant Defy1. I planned to make my frame 52mm wide, and the down tube 60mm deep. This large sized downtube should offer good frame rigidity and also show off the wood nicely. Once hollowed out, the frame would be 5mm thick. I'm not a stressman so I was not able to calculate that such a design was strong enough, but from my discussions with Jay, Nick and Craig, as well as looking at all the pictures I could find online, this seemed to be in the 'ball park'. 

giant defy bike framebike 











Handily, Giant publish details of their bike frame geometry - but I always had the real thing in the workshop so I could also pop out and do extra measurements. I tweaked and tweaked until I got an outline shape for the bike frame that I thought would work. I set my mind on just how I was going to do this and what jigs I would need.


Bicycle Frame

© Christopher Thompson