Tank slapper, speed wobble, head shake… no matter what you call it, when it happens on a motorcycle—especially a road racing motorcycle, it’s usually bad news.
Racebikes have powerful engines, short wheelbases, and aggressive steering geometries that enable them to make very quick changes in direction. The side effect of that flickability is decreased stability, less feedback from uneven road surfaces, and a machine that is more difficult to control. When the front wheel touches down after a small wheelie and it’s not completely in line with the bike’s direction of travel, the result is an unwanted wobble.
A steering damper is a special device that helps to manage the forces acting on a motorcycle’s front end. It’s specifically designed to inhibit undesirable, uncontrolled movement or oscillation of a motorcycle’s steering mechanism. In other words, it helps control tank slappers.
So, how do steering dampers work?
Available either in a linear and rotary style, steering dampers are hydraulic mechanisms that increase resistance to movement in motorcycle steering systems. Linear steering dampers are similar to a shock absorber, and they have a rod and piston that slides through oil. Rotary steering dampers are mounted on the top of a bike’s triple clamp, and they have a unit that forces oil through small passages. With linear or rotary in design, most steering dampers are adjustable, usually with a small knob.
With a steering damper installed on a motorcycle, the handlebars require more input to turn from side to side, which helps the rider maintain control of an unintended motion, like a head shake at high speed.
If a steering damper controls the bike’s steering, doesn’t it make it harder to turn the bike’s handlebars?
Most steering dampers provide progressive damping, which means that the more force you apply to the handlebars, the more resistance is provided by the damper. When a motorcycle is sitting stationary and you turn the handlebars from lock to lock, it probably won’t feel any different with or without a steering damper mounted. But, get the bike rolling, and that’s when you’ll feel the difference.
Will a steering damper completely eliminate tank slappers?
A steering damper won’t make your bike completely tank-slapper-proof, but it definitely helps quell the majority of them. The thing to remember is that a steering damper will not fix handling problems in the bike that are caused by everything from loose steering-head bearings, to an out-of-balance or out-of-round front tire, to a bent wheel or frame. A steering damper is not meant to be a band-aid solution to a larger, underlying problem. The key is to make sure that all is well with the bike’s chassis first, and then, a steering damper is the last step in the handling package.
During your next race weekend, when you’re walking around the paddock and checking out the bikes, take note of how many of them have steering dampers installed on them. Almost all of them do. Sometimes, it’s difficult to find them on a racebike because they may be partially concealed by bodywork or onboard equipment.
Most road racing motorcycles are sweet-handling machines, but even the best-handling motorcycles in the world can usually benefit from the addition of a steering damper. It’s that little extra – like a cherry on top of an ice cream sundae – that can put a rider in the winner’s circle.