Why does "Tankslapper / headshake on exit" happen?

The most common causes are: Preload, Loose arms, progressive throttle on corner exit, Sag. Check them in this order; it is often the setup, sometimes the technique.

All symptoms

Tankslapper / headshake on exit

When your bike shows "Tankslapper / headshake on exit", these are the most likely causes - ranked by relevance: Preload, Loose arms, progressive throttle on corner exit, Sag. LAISA separates setup causes (adjusters, components) from riding technique.

Short answer for this problem

Recommended starting point: Check first: Shock: Preload
Most important change: Smallest documented change: 1 mm
Why: Nose-low/rear-high attitude: reduce rear preload (and/or add front) to calm it down.
How to test it: Read the current value off the bike and compare it with the recommended one. Write it down before you change anything.
Source: LAISA diagnosis catalogue, drafted automatically and editorially released Methodology →
Last reviewed: No review date documented

Pick your bike to apply the fixes directly →

The order comes from the stored strength of the symptom-cause link in the catalogue - per symptom, not across symptoms. These are not probabilities and not measurements.

Suspension

Shock: PreloadCheck first

Why this could fit: Nose-low/rear-high attitude: reduce rear preload (and/or add front) to calm it down.

How to check it: Read the current value off the bike and compare it with the recommended one. Write it down before you change anything.

Smallest change: 1 mm

Shock: SagCheck next

Why this could fit: Front/rear sag balance is off - measure it before turning anything.

How to check it: Read the current value off the bike and compare it with the recommended one. Write it down before you change anything.

Smallest change: 1 mm - loaded, rider in gear

Fork: ReboundCheck next

Why this could fit: Front rebound too stiff hinders recovery over exit bumps - open it a touch.

How to check it: Read the current value off the bike and compare it with the recommended one. Write it down before you change anything.

Smallest change: 1 click - clicks out from fully closed

Hardware

ChassisRarer

Why this could fit: Steering-damper setting or condition - add damping or have it serviced.

How to check it: Check the part's condition and that it is properly seated before touching the setup.

Technique

Loose arms, progressive throttle on corner exitCheck first

Why this could fit: Stiff arms feed the oscillation - stay loose, smooth throttle, let the bike settle itself.

How to check it: Ride the drill deliberately for a few laps on the same section and watch whether the behaviour changes.

How to set your sag →

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Related symptoms

Bike will not hold a tight line Front chatter on corner entry Front pumps / dives harshly under hard braking Front pushes (understeers) on entry

A starting point to verify on the bike - not a safety guarantee. Change one thing at a time and check on track.