It all starts with the length of a spoke.
www.spokelength-project.com/calculator
The Project Calculator will calculate spoke lengths for:
It uses elongation equations to determine more accurate spoke lengths which is important if you are using stretchy thin spokes such as Sapim Laser, Sapim CX-Ray, DT Revolution.
As well as spoke length data, the calculation output produces many other useful data values for spoke entry angle, spoke head clearance, tension ratio and many other values. Plus lots of other useful features that will be appreciated by wheelbuilders.
It contains a lot of expert knowledge to trap bad entries and give advice. And a HUGE built in calculator help guide. All presented in a clean simple interface.
The calculator also draws a scale diagram of the wheel and allows you to explore the wheel in detail using display options. The diagram is also used to show you how to lace the more complex patterns such as triplet lacing and for lacing patterns where there are multiple spoke lengths per side. The diagram is also used to study wheel geometry, and if you like Math and Geometry then the calculator will keep you occupied for days!
1987 I needed to build my first wheels, my current "handbuilt wheels" from someone else were useless and would never hold up to what I was intending to do. Building a wheel is not difficult, but what about the spoke lengths, building can't start without first knowing the length of the spokes. So it was a bit of trigonometry, buy the spokes, build the wheels, then start preparing for the Three Peaks Cyclo cross (look that one up if you are unfamiliar with it). Spoke lengths and wheels were great, and performed as required.
As you probably know, building your first wheels takes you into another world of cycle mechanics, a separate hobby in itself. My new wheels were great, but I wanted to understand why my previous wheels and those used by people I knew were not so good. And then on to spoke lengths where I found many wheelbuilders struggled with spoke length calculations. So I produced some printed information on how to calculate spoke lengths. My job in the real world was in manufacturing systems in an engineering environment, system specification, user manuals and end user training, plus I had a technical background in mechanical engineering.
Printed material only reaches a few people, online is where it needed to be. When the Netscape browser introduced frameset layouts it was possible to write a decent online calculator which soon became the number 1 calculator available (it was also popular with the web programming community and often cited as an example of complex frameset design and user interface). Calculator number 1 was featured in early editions of the wheelbuilding book.
There was more I wanted to do, but I had to wait until web browsers improved, in particular the programming environment (Javascript) and the method of controlling the display (style sheets). Finally, Microsoft Internet Explorer was consigned to history, web standards were now in place and modern browsers adhered to them. So calculator number 2 was written and introduced a lot of cool features. By then I had a professional wheelbuilding shop and I kept adding features that I needed for spoke length calculations in my own business - which other people appreciated as well.
When I closed the wheelbuilding shop I had time on my hands, fortunately I enjoy Math and Computing and still built a few wheels, so I decided to write the ultimate spoke length calculator that would do everything. Now I could take advantage of modern computers and phones that had more than enough power to cope with complex formulas and graphics. Hope you like calculator 3 which is used on this website.
The Project Calculator uses a CAD based model using vector algebra with algorithms designed to cope with some very complex lacing patterns. Note, ALL other calculators you come across use the old fashioned spoke length formula (the one with square root of this that and the other and a cosine) which limits them to what they can do.
For the record, over the years I have built a LOT of wheels and I have never got a spoke length wrong.
All the other calculators out there were written many years ago and are unlikely to ever get updated. Being old, they only provide a basic calculation for J bend hubs, although a couple of them cater for straightpull hubs. They do not carry out any error checks or give any warnings, they all just push the numbers through a very basic spoke length formula. Two old calculators that I respect are Freespoke (www.kstoerz.com/freespoke) and the WheelMaker (www.spokecalculator.net which uses vector algebra, but it's not intended as a production spoke length calculator). The rest I have no time for, for me they are totally unsuitable for modern day wheelbuilding, and that includes the calculators from Sapim and DT who actually make spokes yet have very poor spoke length calculators. I'm not being disrespectful to the other calculators, this is just the reality of the situation.
Please support the project by buying the wheelbuilding book. The book is tightly integrated with the calculator and makes many references to it. It also has a full chapter on spoke lengths which ideally you should read before using the calculator.
If you buy a book, then thanks for supporting the Project.
Roger