Repair / Problems / Gearbox and gear change / Stuck in one gear

Gearbox and gear change

Stuck in one gear

Do not rideAlso called: gearbox jammed, cannot change gear, gear lever locked

Gear shaft parts laid out in an egg carton
Gear shaft parts laid out in an egg carton
Horizontally split crankcase with gears in place
Horizontally split crankcase with gears in place
Shift drum with three shift forks
Shift drum with three shift forks
Gear with broken teeth
Gear with broken teeth

The bike will not change out of one gear: the lever will not move, moves without doing anything, or moves but the gear stays the same. You may not be able to find neutral to stop. Sometimes the dogs inside are simply jammed against each other and free up when the bike is rocked. Other causes are a lever slipping on its shaft, a broken clutch cable (so the clutch never releases), or a broken fork or guide pin inside the gearbox.

Is it safe to ride?

No. You cannot stop without stalling or pull away safely. Move the bike off the road. If the clutch still works, you can push it with the clutch lever pulled; if not, transport it.

Quick checks first

  • Is the clutch cable intact, and does the lever have normal feel?
  • Is the gear lever still tight on its shaft?
  • Was the bike dropped, or did the chain come off?

Diagnose it step by step

1Engine off, clutch lever pulled. Rock the bike backwards and forwards while pressing the gear lever gently. Does it change?

  • Yes: the dogs were jammed face to face. It should now work normally; if it happens again, go to Gears are hard to select.
  • No: go to step 2.

2Does the clutch lever have normal resistance, and does the clutch release?

3Does the gear lever move freely without changing anything?

4Does the lever move one way but not come back?

5Is the lever or linkage blocked by something outside (bent against the case, a stone, a dropped chain behind the sprocket cover)?

Do not force it. Kicking or levering the gear lever hard can bend the shift spindle and forks, which turns a small repair into a large one.

Causes, most likely first

Cause How to confirm Fix
Dogs jammed face to face Frees when the bike is rocked No repair needed
Clutch not releasing (broken cable) Floppy clutch lever Replace the clutch cable
Lever slipping or linkage disconnected Lever moves, gear does not Refit or replace the gear lever
Lever blocked outside the engine Visible obstruction Clear it; Check the gear lever and shift linkage
Broken fork, guide pin or gear Solid lever, nothing outside Assess internal gearbox faults

Videos that help with this problem

How it worksHow a motorcycle transmission works (Animation)TecknoMechanics · 6:08 · YouTube

Animation of a constant-mesh sequential gearbox: gears, dogs, shift drum and forks. Shows shift drum, forks and dogs, which explains false neutrals, jumping out and hard shifts.

Videos by their creators on YouTube, chosen because they show this clearly. Values in a video are for the bike shown; use your own bike's manual.

Related problems

Sources
  • K-Light 125 manual, PDF pages 31, 191, 230, 231

Values marked K-Light 125 are for that reference bike. Use your own bike's manual for its values. Text CC BY-SA 4.0, Transitions Lab.