Tank slapper, speed wobble and head shake: what causes them and what helps
Short answer
Head shake is the bars oscillating side to side, usually at speed or after a hit. Check the steering head bearings, front tire and suspension setup first. A steering damper slows the movement, but it does not repair a worn or loose part.
Tank slapper, speed wobble, head shake: same family, different names
Riders use these words loosely. Head shake is the common term for the bars shaking side to side, and it is the one off-road riders reach for. Tank slapper is the violent version, where the bars swing far enough to hit the tank. Speed wobble is the phrase road riders use for the front end oscillating at speed.
They are different sizes of the same problem: the front wheel and bars start to oscillate and the oscillation feeds on itself.
What sets it off
Scott's lists the usual triggers as bumps, rocks, roots and ruts, letting off the throttle so the front end dives or goes light, and landing slightly off line after the front wheel lifts.
Speed makes every one of them worse. A bike that is calm at 40 mph can shake at 70 over the same surface.
Check these first
A damper hides these faults without removing them, so rule them out before you spend money.
- Steering head bearings. Loose or notchy bearings let the front end move when it should not.
- Front tire. Check wear and pressure. A worn, cupped or under-inflated tire can start a wobble.
- Fork height in the clamps. Moving the forks changes the head angle and how quickly the front end settles.
- Suspension setup. Sag and damping that suit your weight and speed keep the front wheel on the ground.
- Wheel balance and hardware. An out of balance wheel or a loose axle adds its own vibration.
If it starts while you ride
Stay relaxed on the bars instead of gripping hard, ease off the throttle smoothly, and avoid grabbing the front brake. Slow down, find a safe place to stop, and go through the list above before you ride again.
How a steering damper helps
A steering damper is a hydraulic unit at the steering head. Oil moves through valving that the rider adjusts, and the valving resists fast left to right movement of the bars. Slow, deliberate steering stays easy, while the sudden snap that starts a shake is slowed.
It lets the rest of the suspension do its job. It does not replace it. Our guide to whether you need one covers who gets the most from a damper and who can skip it.
Dirt bike or road bike: the valving differs
Scott's says its road units have rebound damping that works back toward center, while its off-road units damp as the bars turn away from center and let them return freely. That is why a kit made for a dirt bike is not the one to fit on a sport bike.
Find a stabilizer for your bike
Choose by bike type, or go straight to a popular model: Kawasaki ZX-6R, Yamaha YZ 250, Yamaha Tenere 700 or Suzuki SV 650.
Questions
Will a steering damper stop head shake?
It reduces side to side movement. It does not cure loose bearings, worn tires or poor setup, so check those first.
Can a damper make the steering feel heavy?
Scott's says its units are adjustable, including while you ride, so slow riding can use a light setting.
Is it safe to ride without a damper?
Most bikes leave the factory without one, and most riders never need one. If yours has shaken at speed, fix the cause first and then decide whether a damper is worth adding.