The correct spoke length is the key factor that affects the durability and reliability of bicycle wheels. A reliable wheel builder should be able to choose the correct spoke length in order to build wheels that will last for many years.
Mistakes in this area happen to everyone – from small workshops to the largest brands. Unfortunately, it happens to us as well. There is no more depressing moment in a wheel builder’s work than when, after trying hard to look at it from different angles and bending reality, he has to admit that the wheel was built on spokes of the wrong length. The only correct solution to this situation is to disassemble the wheel and re-lace it with new spokes of the correct length using new nipples. Unfortunately, many mechanics at this point decide to betray physics in favor of magic and start to “conjure”.
The most common trick is to use longer nipples to hide the protruding threads of too short spokes. In most cases, nipples have the same amount of thread regardless of length and it is located in the “rear” part of the nipple.
This procedure leads to the inevitable cracking of the nipples after a short run, because they do not work as an extension of the spokes. The acceptable margin of error in choosing spokes is really small – the entire thread of the spoke must be covered with the thread of the nipple. To assess whether the spoke length is properly selected, you should look from the back of the nipple under the tape or strip. Using too short spokes can also cause the spokes to crack on the first turns of the thread.
Too long spokes generate significantly fewer problems, as long as the protruding part is no longer than a millimeter. If the spokes are longer by two millimeters or more, it means that the tension force of the spoke is distributed over a smaller number of thread turns. Sooner or later this will cause problems.
The basic tool for calculating the spoke length is special calculator. However, they do not consider a number of factors, such as the cross-section of the spokes or the way they are crossed. The values given by the calculator should be treated as suggestions, not final results. This is why we do not build wheels on spokes supplied by customers or give advice on their selection. To be sure about the choice of spokes, we must have all the components in our hands.
Spokes are available on the market in lengths that follow each other by 2mm – for example 280mm, 282mm, 284mm etc., and the results of the calculator calculations often suggest the use of 281mm, 283mm, 285mm. This means that wheel builders are often forced to compromise. The solution to this situation is to shorten the spokes to the desired length with an accuracy of a millimeter. We are fortunate to have the best available market Morizumi machine, which allows for quick shortening and threading of spokes. Thanks to this, the wheels we build always have the perfectly chosen spoke lengths. We do not compromise on this field.
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