Gears shift badly (geared bike)

The lever catches, gears crunch when shifting, neutral is hard to find, or gears pop out while riding. On a bike with a manual gearbox, these symptoms have very different origins depending on whether they come from an adjustment/maintenance issue (the most common and accessible) or from the gearbox itself (rarer and more serious). The key distinction: does it CRUNCH when shifting (the clutch isn't separating the plates properly), or does it POP OUT of gear under load (internal wear)? The accessible causes: a poorly adjusted clutch (excess free play means it doesn't disengage fully, causing crunching and a stiff neutral), and worn or unsuitable engine oil — an important reminder: on a motorcycle, engine oil also lubricates the gearbox and clutch, and tired or non-compliant oil (with 'friction modifier' additives) stiffens shifting. Next comes a bent shift lever or linkage (often after a fall), which gets in the way of the lever's travel. Finally, the serious case: worn gearbox shift forks or dogs, which cause gears to pop out under load and require opening up the engine (professional work). You can tell them apart by the type of symptom (crunch vs. pop out), a clutch test (does it disengage fully?), and the context (right after a fall?). Urgency threshold: hard shifting isn't dangerous in itself, but gears popping out can catch you off guard, and forcing a crunching gearbox wears it out prematurely. Always start with clutch adjustment and oil (free/cheap) before suspecting the gearbox itself.