Have you ever found yourself at the bottom of a run—or even halfway through—and had to shake out your hands? Or tell yourself, “Suck it up, Buttercup!” while holding on for dear life and nearly lose your front wheel by the bottom? Those high-frequency, low amplitude vibrations, or what we call “trail chatter,” can cause your wheel to lose traction, lead to hand fatigue, and even, as one rider put it, "vibrate your eyeballs." Think of hoofprints in dried mud, small rocks at speed, and shallow ruts—these short and fast frequencies can put an end to an otherwise good day. While dampers are designed to absorb impacts, trail chatter can often make its way past the damper, up the fork, and into your hands.
During the Charger 3 damper development, a handful of engineers were talking about the frequency domain and how to study suspension through this lens. While chopping up a tree with his brother one day, RockShox Senior Design Engineer Tim Lynch discovered the frequency domain in real life, off the bike. Tim’s chainsaw had a rubber-damped grip, while his brother's chainsaw did not. His brother complained of his hands going numb, and it clicked for Lynch that this was the frequency-based damping he had been discussing with his colleagues. The rubber-damped grip prevented the chainsaw's rattling vibration from fatiguing his hands so that he could work longer, and more comfortably, than his brother. Lynch brought this idea to his colleague, Design Engineer Skyler Teachout, who turned to his desk drawer and pulled out what looked like a piece of rubber attached to metal but was actually a version of a frequency isolator. "You mean, like this?"
What, exactly, are ButterCups?
ButterCups live on both the damper and air spring shafts of Ultimate-level forks. Inside their gold packaging, ButterCups utilize rubber pucks and a metal plate to absorb frequencies that would otherwise travel up to the rider.
Now, let’s move over to the air spring side: ButterCups on the air spring shaft work very similarly, but the spring side is biased to be more effective on the compression stroke versus the rebound. Therefore, the air spring shaft only has one taller rubber puck and utilizes an O-ring when the system extends again.
These little ButterCups add about 4mm of vertical compliance to your suspension and an average of 20% reduction in trail chatter from reaching your hands. All of this happens whenever your bike is in motion.
Development and Testing
The first time Lynch tried what became ButterCups on his bike, he was pleasantly surprised at how it felt: "The first thing I remember riding was dried mud with a bunch of footprints, and as I was riding across, it was just silent."
Feel safer and go faster with out the fatigue. That’s why we redesigned the Charger 3 damper and why we created ButterCups. Say yes to an extra lap.
Renderings by Ray Bach. Photos by Mason Mashon and James Stokoe. Words by Sarah Walter.