The Basics

FreeSpoke is a spoke calculator designed to address some of the shortcomings and frustrations I have had with every spoke calculator I have used. Instead of an outdated and vague list of rim and hub data, FreeSpoke offers a centralized database of rim and hub information. This data is user-contributed and maintained, so you can enter your favorite parts for everyone to benefit from. No more keeping lists of measurements to enter into calculators by hand!

The Math

The geometry formulas used by FreeSpoke were adapted from Damon Rinard's highly-regarded Spocalc spreadsheet, which was a big part of the inspiration for this project. In addition to using what is possibly the best and most complete spoke length formula, FreeSpoke also calculates several other useful values to give you a better picture of how a potential wheel will build up.

Behind the Scenes

FreeSpoke is powered by PHP and a MySQL database. Everything you see here was assembled and coded from scratch, starting in October of 2009. This is very much a work in progress, and I welcome feedback, comments, bug reports, etc.

Resuming Development!

Freespoke has been functional yet incomplete and not actively under development for several years now. As of August 2016, I have carved out some time to pick up where I left off. The live site hasn't been changed other than to fix a few minor errors/warnings/bugs, but development has resumed offline! My priorities are to bring the existing code up to modern standards (lots has changed with PHP and MySQL since 2009!), then integrate the existing OpenID login system (as seen in the tension balancing utility) to allow a single user account to be used for everything on, then work hard to get FreeSpoke ready to allow users to contribute to the database of rims and hubs. There's a lot of work to do, and I still fix bikes 40 hours a week to pay the bills, so I know this will take a while. If you have ideas or thoughts or encouragement, please feel free to email me (the address is below).

October 2018 Update

Some major updates went live on 10/16/2018 including rim and hub submission forms, triplet lacing calculator, new wheel side-view renderings improved rim and hub renderings, improved wheel cross-section rendering, organizational and aesthetic improvements to many pages. The main backlog of changes and improvements is now live, but more is in the works behind the scenes.

Karl Stoerzinger
Minneapolis, MN
kstoerz at gmail dot com

My instagram has lots of bike mechanic and wheelbuilding stuff.