The modern approach to calculating wheel building spoke lengths.
It will calculate spoke lengths for:
The calculator uses a CAD based model using vector algebra with algorithms designed to cope with some very complex lacing patterns. It uses elongation equations to calculate very accurate spoke lengths which is important if you are using thin stretchy spokes such as Sapim Laser, Sapim CX-Ray and 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, and worksheets for use whilst you build your wheels, plus data saving options, in short features that are appreciated by experienced 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 is used every day by some serious wheelbuilding shops.
The calculator also draws a scale diagram of the wheel and allows you to explore the wheel in detail. 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!
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 all use the old fashioned spoke length formula (the one with square root of this that and the other and a cosine) which severely limits them to what they can do. They provide no useful information for wheelbuilders - just basic spoke lengths without stretch compensation. This is not being disrespectful to the other calculators, and this includes the calculators provided by the spoke manufacturers Sapim and DT Swiss, this is just the reality of the situation.
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. 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 struggling 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 build 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.
For the record, over the years I have built a LOT of wheels and I have never got a spoke length wrong.
www.spokelength-project.com/calculator
Roger