Exploding Spokes?

June 20, 2014 4 Comments

Wheel builders have an intense curiosity about the small details. Riders are concerned with the entire wheel and its performance. We builders want to know every “why” about the structure.

Steve Liming of SRLPE Wheel Works in Scottsdale noticed something unusual the other day. Steve is a professional engineer and well regarded builder, I’m eager to hear his observations. Thanks to the network of curious wheel builders, the subject is expanding. I will follow this post with more detail and data.

For the time being, remember that we don’t know all there is to the complexity of the structure and the materials used in our wheels. Sometimes it is all within expectations. But we’re always challenging the status quo and new products are raining down. One rider or builder’s weird or unpleasant experience might bring valuable insights available no other way.

Here are spoke ends. These were ridden hard off road, the wheel unbuilt, spokes shortened a couple millimeters, and threads rolled. Wow, in my 40 years of staring at spokes I never saw something like this.

Another view, here from the side. Yup, the spoke is exploding.

What we want to know is:

(1) Are these spokes exhausted from hard riding?

(2) Is trimming and rethreading spokes too much to ask of the material (stainless)?

(3) Are the spokes defective, brittle, weak, contaminated or what?

(4) What happens to cause reliable stainless to fracture, crumble, and develop lengthwise holes?

Good news, there’s no epidemic, this is rare. But we need to understand the causes. Check for a followup post with answers to the above questions. I have some guesses but I think we’re in for some surprise, too. If you have personal experience like this or special insight, now's the time to share.

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