Last night I was out on the R6 riding as usual.  Not very aggressive, just zippin' through the twisties at a comfortable pace on my way to my favorite coffee shop.  My chain was in good shape.  Cleaned and lubed about 500 miles ago (a few weeks).  Slack looked good, etc.  Just as I crested mount nittany I lost power to the rear wheel completely.  I heard a very slight gringing sound as I coasted to the bottom of the mountain to inspect the bike.

somehow the chain had jumped off the front sprocket!!!     The grinding sound was the chain getting chewed up as the rear sprocket forced it around.  I have no idea how it happened.   There was no indication that the chain was lose or the sprocket was failing... it just jumped... on the smoothest section of the whole road no less.  :dunno:

I was riding alone after dark.  If my chain had gotten caught and I binned it I could have been hanging off the side of the mountain all night waiting to bee seen by someone.   Not a cool experience.   BE CAREFUL AND WEAR YOUR GEAR... you never know when its gonna hit the fan.

A good lesson for all of us no doubt.

 -Anti

Does your "proper gear" include a St. Christopher medal, a rabbit's foot, or some other lucky token? Your incident was definitely the best-case scenario.  Did the chain chew into the engine cases?  

That sucks, you didn't do any damage to the cases or water pump did you?

I'm pretty sure I lucked out in the collateral damage category.  looks like the chain got ground up a little bit, buy my mechanic says all the damage was to the chain/sprocket.  He races an R6 and says he has seen more than one chain derailment, so I trust his judgement.  Overall, it should only set me back about 250 to 300 bucks for a chain/sprocket kit plus labor.

I feel like a dodged a bullet  

There's no way in hell I'd ride a motorcycle that had a tendency to throw chains, no matter how rare the occurence (I have an older road bicycle with Ultegra 8 speed that is painfully proficient at this, thank you very much).

There's a lot to be said for "slow-handling, underpowered" motorcycles--  no barrel rolls on the highway and chains that don't fly off sprockets.  Has sportbike design become too razor-edged for safe use on public roads?

I don't think sportbikes are too 'razors edge' to be on the roads.  They are designed to handle stresses far in excess of what I put mine under... I ride mine quite gently by sportbike standards.   I'm uncertain what went on exactly... but the R6 is the last of the supersports to hang on to the 530 chain while the rest have pushed down to 520 in the quest to shave weight.  the final drive on the R6 is actually the most robust of all the supersports.  :dunno:

I bought the bike used.  I don't think the drive system had been messed with, but I don't know what else to blame it on, because apparently the nut and lockwasher for the front sprocket were nowhere to be found... maybe someone is trying to kill me  :dunno:

I'm pretty sure I read in the specs for my 600rr that it also has a 530 chain.

I'll have to verify when I get a chance...

DUDE, double check the casings around the front sprocket very closely, my GS did the same thing and nearly destroyed its self, JBWELD was very helpful and fixed the break