The short answer: yes, chains snap — and almost never without weeks of visible warning first. Understanding how failures happen is the best argument ever written for the boring maintenance this site keeps preaching. Here's the anatomy of a chain failure.
What a snap looks like from the seat
A bang, instant loss of drive, and then physics chooses from a menu: best case, the chain drops onto the road and you coast to a stop (the response protocol is in the derailment guide — clutch in, no panic braking). Worse cases: the loose end whips forward into the rider's leg or the engine cases — chains have holed crankcases, ending engines — or the chain bunches between sprocket and swingarm and momentarily locks the rear wheel. All of it argues for taking the precursors seriously.
How chains actually fail
Almost never by a healthy link breaking — tensile ratings carry multiples of any bike's power. Real failures come from: worn chains ridden past the limit, where elongated pitch loads pins at bad angles and side plates fatigue; seized links, which concentrate stress on neighbors every revolution (the stiff links from rust or dead internal grease); master link errors — missing clips, backwards clips, under-flared rivets (the rules); chronic over-tension hammering pins at every suspension hit; and impact damage off-road. Note the pattern: every one is visible or preventable in advance.
The warning signs, in failure order
A chain heading toward failure fails the pull test (measure it), shows kinked or stiff links on a slow wheel-spin, develops new noises, needs constant re-adjustment, and rides on visibly hooked sprockets. Any two of those together is the chain filing its resignation — the full checklist is the wear signs guide.
Prevention is embarrassingly cheap
The entire anti-snap program: keep the chain clean and lubed so links never seize (the one-minute CC360 habit plus proper lubing), keep slack in spec, install master links by the book, and retire chains at their measured limit instead of their financial one (the cost math favors it anyway). Chains on that program don't snap; they get replaced on schedule, undramatically, which is the whole point.
Quick answers
What happens if a motorcycle chain breaks while riding?
Usually sudden loss of drive and a loud bang; the serious risks are the chain whipping into the rider's leg, punching the engine case, or bunching at the sprocket and locking the rear wheel.
How common is a chain snapping?
Rare on maintained chains — the overwhelming majority of failures happen on chains showing advanced, visible wear or after improper master link installation.
What causes a chain to break?
Worn-out chains ridden past their limits, seized links concentrating stress, badly installed master links, over-tension, and impact damage — usually in combination.