rattleCAD supports bespoked bicycle frame builders with a fully parametric bicycle model inside. It is a free and open source bicycle geometry designing application that's portable, light on system resources and well-designed.
Here are some screenshots to illustrate the features and user interface of this application:
Create a bicycle's geometry while picking various elements from different preset system components. Screenshot of rattleCAD - 922px · 812pxrattleCAD: Bicycle design. Screenshot of rattleCAD - 322px · 669pxCAD program for designing bicycles. Screenshot of rattleCAD - 556px · 480px