Slightly off topic - I cad draw all my frames onto one AutoCAD drawing. 2-D, bottom bracket as origin. Each serious bike gets 3 layers; centerlines of tubes and hub centers, outlines of tubes and parts/wheels. This has been very, very useful. I've had a frame built from it that is the most fun ride I've ever had. I do quick measurements of potential purchases and lay them over this drawing to see if I want it and what stem I need. I sometimes dream up new ideas and save them as new layers.
Around the same time I started this drawing I read an article the author of which opined that trail vs quickness of steering wasn't a constant over varying head angles but instead could be approximated with a line. He gave the slope. (I think in terms of rake vs head angle, not trail. So I made up an AutoCAD drawing of rake vs head angle. Plotted the bikes I've owned. The bikes I've liked fell on a parallel line (I like quicker steering than the author.)
The frame of my logo photo was designed on my frame drawing and sent to TiCycles to be engineered and built. (I didn't spec tubes. Dave Levy knows that stuff far better than I.) The dropouts came right off my drawing. An 11 degree angle to horizontal, roughly 2" slot and opens down at the front so the slot is "L" shaped. Cut from 1/4" plate. The angle was chosen to be as close to horizontal as possible while still keeping the brake pads on a Velocity Aero semi-deep rim. I can run any cog between 12 and 24 teeth without messing with either chain length of brake pads (or derailling the chainring to get the wheel out/in). A joy for quick fix gear wheel changes/flips. I do on the road wheel flips all the time. 2 minutes and completely clean hands. I can remove the wheel and change a cog in 5.
So - 2-D cad drawings for frames? As a lifelong enthusiast (maybe a little more serious - over the crazy post TBI years cycling was my link to sanity and away from drugs, institutions or death) its been both a lot of fun and a gift. Being able to send a builder the drawing saves a lot of misunderstanding.
Last edited by 79pmooney; 06-27-21 at 11:49 AM.
Reason: Accidently hit send mid-way through writing this