New England is a great place to go mountain biking. Besides the amazing scenery, the fresh air and the seemingly endless supply of technical trails to ride, it’s also the only place where you can get away from the notorious New England traffic jams. Typically, when I mountain bike I don’t shy away from roots, big rocks or drops, resulting in some real stress on my bike.
An Unfortunate Turn of Events: My Bike Wheel Broke
After riding for multiple years without ever breaking a spoke, my wheel started making a weird noise. Sure enough, a spoke had snapped. I bent it over so it wouldn’t get caught up in my disc brakes and didn’t think much more of it. I still had 31 out of 32 spokes, and it’s not like I am going off Red Bull ramps in the Utah desert. It wasn’t much longer after the first spoke when I noticed another one had broken. This was a little puzzling to me. Maybe I was doing something different when I was riding? I had gone years without even one spoke breaking and now I get two on the same wheel within a week?
I didn’t let this unfortunate turn of events bring me down, so I forged ahead and kept on riding with the same vigor as always, but then the unthinkable happened. A third spoke broke! I was frustrated to say the least, so I brought my problem to the type of person I trust the most, someone else named Andy.
SOLIDWORKS Simulation Study
After telling Andy Jaskey about my problem he suggested that we talk to Keith Pederson about possibly creating a SOLIDWORKS Simulation study. After some fun data collection, Keith told us what he found. As it turns out, even though I only lost one spoke, it threw the entire system out of balance. In fact, it reduced the overall strength of the wheel by almost 20%, even with 97% of the spokes remaining. This was something that wasn’t immediately obvious to me, but after seeing the simulation results, it made perfect sense.
Each spoke is in tension, pulling equally on the hub. Once one is removed from the system, all the other spokes are out of balance and are now exposed to carry much higher loads. This meant that as I rode, many of the other spokes were getting very close to yield, and even though they didn’t all break at once, given enough time another one did. This put exponentially more stress on all the other spokes and so on and so on. We could see this in the results by removing the one spoke that broke and then running the same study, seeing which spokes go over yield and then removing them.
Conclusion
After looking at this problem inside of SOLIDWORKS simulation, it was easy to see reason in a problem that seemed like a random phenomenon. This is the sort of thing I always appreciate as an engineer. If I understand the system I can use it to my benefit. This means in the future, if a spoke breaks, I will ride out of the woods very carefully and then patiently sit in traffic on my way to the bike shop to get my spoke replaced.
Watch the FEA Analysis, performed by Andy Jaskey, in SOLIDWORKS Simulation!
