bonnie & jason

Bike geometry spreadsheet

By jason, November 24, 2008 on 3:18 pm | In biking | 4 Comments

In preparation for the bike build, I’ve been doing some research on bike sizing and how geometry influences handling. Unfortunately, I couldn’t find anything that really told you how long to make certain parts of the bike, particularly the chain stays and seat stays. So I put together my own spreadsheet based on basic 10th grade geometry.

Here’s the graphic:

And the calculations:

Here’s a link to the file itself for those of you who might want to use it for your own bike build.

Clearly, I’m a geek, but hey… the world needs geeks!

EDIT: A had a problem with one of my calculations that determine the downtube length. I still haven’t figured it out yet, but fellow Dork (yes, that’s Dork with a capital “D”), and Cornell Mech E, Pete, laid it out for me in Inventor and did away with all that silly trigonometry to provide the right answer:

I owe Pete a beer next time I see him. Plus, at his suggestion, I’m downloading Inventor LT so I can replace all that spreadsheet dorkiness with some modern CAD dorkiness.