Chain Failure Disasters

[sumo]

My chain has 24,000 km on it. To me it looks fine as do the sprockets. What happens when a chain fails? I mean, I understand that a broken chain means you've got no power and you'll be rolling to a stop. Not a great scenario if you are in the fast lane of a busy interstate or out in the middle of nowhere. But hey, is there a good place to break down?

Does it happen that a chain failure is more dramatic? Do chains ever wrap up in the wheel causing it to lock up? Or fly up and wrap around your neck then pull you under a bus? Or fling off and go through the windshield of the car behind you?

Does anybody have a chain failure story?

 

[Michael Moore]

You can get a broken engine case if it wads up around the engine sprocket. The Honda has a metal guide to help prevent that.

Honda Motorcycle Parts 2013 NC700X AC ALTERNATOR COVER Diagram

#3 plate drive chain guide

 

[ste7ios]

Many things can go wrong. The power loss may be enough cause for an accident. You may have a lowside if that happens during leaning... You can't know...

Maintain it well, replace it in time and it will be ok. It's an extremely rare case to bother you...

 

[Doc True]

If it looks fine, it is fine. Don't worry about it. Chains don't break due to age but they do wear out through use. If it looks too worn to ride, replace it. The job is cheap and easy (like your mom). If your not sure if the set is worn enough to replace, post a picture. There's quite a bit of useful knowledge on here if know who to listen to.



Also, that crack about you mom was out of line. I should really be suspended for it.

 

[670cc]

This is not a reply to your question, but rather general thoughts on the subject.

I would assume, but have not researched it, that chains would break due to weakening of the pins due to wear. I doubt the side plates give way. Wearing of the pins can be somewhat determined by the chain "stretch". The chain wear indicator on the swing arm is there for that purpose. When you reach the wear limit, replace the chain. The only gotcha is there is no way to know if some pins have worn significantly more than others, and pose the greatest risk of breakage. I would like to think there is enough safety margin built into the wear indicator to account for potential variations in pin wear.

Some manufacturers will provide a maximum chain length measured over so many links, which serves the same purpose as the swing arm indicator. I can't recall if Honda published such a spec for maximum chain length for the NC700.

 

[mreric]

Loose Chain Highside Crash - Mulholland - YouTube

it could be something like this

 

[MZ5]

I feel bad for that guy in the vid. Looking closely, though, I do NOT see the loop of chain (it came off the sprocket a while back, so he lost drive power, which I expect is why he raised his hand) suddenly go tight as the rear wheel locked up. Neither do I see any significant change in the chain, visually, as the rear wheel starts slowly turning again. So, what aspect of a caught chain lets go nice and gently while it's locking the rear wheel up, such that the rear wheel can start turning again nice and smoothly? I've never experienced any sort of chain-related lock-up (and I've worked with truly miles of roller chain on tons of equipment over the years) where the chain gently lets go without warning, as the lock-up tension was still on it.

What seems very likely is an operator who was too hard on the rear brake while entering a decreasing-radius corner causing a rear-wheel lock-up, then letting go of the rear brake once he realizes what's happening and reacts by letting go of the rear brake, thus allowing the rear tire to start smoothly turning again, the rear tire to grip the asphalt again, and the bike to highside.