(Originally posted on 2007-06-21)
Above Image: By Matthieu PELLETIER from France [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
I experienced my first tank slapper on 2007-06-20. That's when a harmonic instability causes the handlebars to swap from side-to-side as far as they can go (AKA full lock). I purchased a Suzuki SV650SA7 one month earlier (2007-05-19), and I already have over 1200 miles on it. Anyway, I was coming out of the parking lot on the NE corner of Iowa and 23rd in Lawrence, KS after lunch. These cars were coming at me pretty fast so I wanted to accelerate out-of-there. I gunned it while I was leaned over. First the rear wheel starts spinning, or I hit a false neutral, or who knows what (VROOOOOOM), and then the handlebars are doing a high speed dance (JIGGY-JIGGY-JIGGY), and left foot comes of the peg. Afraid? HAH! Danger is my middle name! Embarrassed? You bet.
Here is a video of a tank slapper that looked like mine:
Here is a much-worse-ending one: