Great Question: Bicycle wheels go out of true for a variety of reasons. Wheels are subject to extreme forces, from withstanding a clattering from an unexpected pothole or rough riding off-road. Over time, or in the case of a heavy hit, this may cause the wheel to go ‘out of true’. Other causes include poor quality build, spokes of poor quality material or lack of spoke prep when building. All these can also cause lose of tension of some of the spokes. For instance, you can have a wheel that has high spoke tension in every other spoke on one side and almost none in alternate spokes. The wheel will be true, but those with little tension may cause the wheel to again go out of true or at the very worse cause a spoke to break or the wheel to collapse (we will show this in an up coming video currently in production). For this reason, whenever we true a wheel, we also check for correct spoke tension. In order to correctly measure spoke tension (use the proper conversion chart), we need to know the spoke material as well as certain diameter/width of the spokes. Also see: www.bikeradar.com/advice/workshop/how-to-true-a-wheel Regards and safe cycling, Tony
Yes to the longitudinal stress as the wheel turns under load but are poor in handling lateral stress from the side (if the bike falls over or hit be a rock). Here are some references: nscarbon.com/blogs/news/the-pros-and-cons-of-carbon-spokes and icancycling.com/blogs/articles/carbon-spoke-wheels#:~:text=The%20lightweight%20wheel%20and%20spokes,compared%20to%20conventional%20steel%20spokes. and www.elite-wheels.com/news/advantages-and-disadvantages-of-carbon-wheels#:~:text=So%20the%20tension%20of%20carbon,hit%20sideways%20than%20steel%20spokes.
I build all my wheels with DT double butted stainless steel spokes. They're strong and have yet to see any corrosion or breakage over the past 30+ years. I use a three across pattern to give me the most strength. Although I have also used a 1x bladed stainless on Bontrager hubs and rims that have held up well.
Mavic has made racing wheelsets with aluminum spokes at least from early 2000s. I am told that they break more often and have higher wind resistance than steel spokes, but not too bad to stop people from buying them. Such spokes are still available via Ebay and a few other sites. Here's an interesting review of aluminum spokes: www.spokemaker.com/why-use-aluminium-spokes/
I still use a magnet but realize its limitations. If it's magnetic it may be ordinary steel (called "carbon steel" or "ferric steel") or DT / Wheelmaster stainless. The DT and Wheelmaster have distinct markings on the "j-hook" end of the spoke. Outside of that, I have to go by color, scratch test or internet search. Luckily, stainless is the most common although carbon spokes are now being seen.
Some BMX riders have advocated titanium spokes, but, for the most part, stainless steel seems to be the preference (kids and cheap bikes may use ferric steel). Here are a couple of forums to look at: www.roadbikereview.com/threads/ti-spokes.265811/ and www.vitalmx.com/forums/Tech-Help-Race-Shop,42/Titanium-Spokes,1371488?mobile=false&page=2#:~:text=Titanium%20has%20about%20half%20the,much%20point%20in%20doing%20that!
There are over 100 grades of stainless steel with 304 and 316 being the most common due to their strength and durability. These latter two are, for the most parts non-magnetic. However, forging (that is molding, working and bending) of the steel may disrupt the molecular properties of the steel, imparting some magnetic effects. Other grades of steel may show more magnetism. This is probably why various stainless steel wheel spokes vary from non-magnetic to moderately magnetic. Good question. Thanks, Tony
