Spinergy wheels.

[fyrstormer]

This article is almost as old as the internet, but pictures here suggest a few people are still riding the old Spinergy wheels, so this is worth a read for them.

http://pardo.net/bike/pic/fail-020/index.html

[shovelon]

 

Although I have never had any issues with mine, I am going to look them over.

[fyrstormer]

The structural analysis is sound: when the spokes are at diagonal angles, there will always be a shear component to the force being applied to them , effectively trying to tear them off the rim of the wheel like strips of paper. On the original 4-spoke design, if one spoke lets go, as soon as the wheel rotates to where that missing spoke is at the top of the wheel, there will be absolutely nothing supporting the weight of the bike and rider, and the wheel will collapse. There was a revised 6-spoke design, as I recall, which is somewhat safer, but the problem remains that having so few spokes means there's very little redundancy in a design that otherwise has no means of graceful failure.

On the other hand, the 857 I bought off Craigslist has normal wheels, and one of the spoke nuts was busted in half, and there's so much redundant support in a normal wheel that I didn't even notice the busted spoke nut until I tried to true the wheel. Those 4-spoke Spinergy wheels look mighty trick -- I was actually searching for a used set when I stumbled on this article -- but there's a reason they don't make them anymore.