A Visual Aid for Bike Design

Author: | Posted in Uncategorized No comments

For Halloween I made a Witch on a broomstick out of 2" thick Styrofoam insulation. I got my 8 year old daughter to pose with a broom and then I snapped a picture with my digital camera. I did an "edge trace" with Paint Shop Pro and used the grid system to transfer the resulting outline to the foam. It occured to me this morning that I could use the same method to make a design aid for my bike project.

styrofoam witch grid

I set my digital camera up at one end of the garage with the lens 3 feet off the ground. I zoomed it all the way in and found the field was about 6 feet wide, perfect for my needs. I placed a piece of peg board with holes spaced in a 1"x 1" grid at the end of the garage to act as a scale. I took a shot of the blank sheet and printed it full size at 600 DPI on my LaserJet 5L. I used an architect's scale to check the linearity of the field of holes and found little variation over the image.

I then placed each of the major components of the bike at the 3 high foot mark and photographed them. When I finished with that I brought my SWB bike into the garage and photgraphed myself sitting on it.

photo copied bike parts

I printed out all of the images and cut out the components with an Exacto knife. I printed several pictures of myself and stacked them in a pile. I then punched a pin through the pages at the points were I thought my joints should bend. I sketched out body parts on each page and cut them out. The paper by itself is a bit flimsy so I attached the body parts to card stock with 3M High Tac spray rubber cement. I attached the crank to a circle of clear plastic and put a tab of clear plastic on the ball of my foot. Pins and pieces of clear plastic were used to connect the joints.

pliobond rubber cement short wheel base drawing

swb drawing

Everything was then pinned to foam board and I had a little fun with Paint Shop Pro's Animation Wizard:

riding a recumbent bike

This will give me an easy to use tool to design the rest of the bike. I've settled on a non-suspended SWB ASS configuration with a low seat but upright posture utilizing a 406 wheel in front and a 700 in back.

However, before I can start designing I need to photograph myself on the SWB so I can see how my ankles really bend as I pedal.