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Discussion Starter · #1 ·
Had a pretty ugly get-off this morning courtesy of some sort of weird jam involving my eagle chainring, 1x chain guide and kmc x12 chain.

Happened pretty fast but best I can remember I was out of the saddle pedaling across a flat section at speed when about 4-5 crank rotations in the bike completely locked up hard and fast enough to shift my weight so far forward that I ended up going over the bars in epic fashion. Simultaneous to that I recall hearing a loud snap.. Lots of labored breath-catching grunts later I gather the bike up to find the chainring missing a tooth with obvious scarring, plus the chain is now outside of the chain guide (away from the frame, as in toward the pedal) and one link bent to where it won't pivot anymore.
Pretty much zero rash on the chainstay behind the chainring and absolutely nothing wrong with the derailleur or cassette either. I'll add that until that last crank revolution it had all performed flawlessly for the last 275 miles of use.

Anyone ever had this happen? Really trying to figure out how the chain got started off in the first place and then what it was leveraged against that had enough force to snap a tooth off of the chainring without damaging anything else...
Full x01 system (other than the KMC which I've had zero compatibility issues with).. same exact mileage on everything (around 275). 2018 Scott Genius 700 tuned for what it's worth Bicycle part Teal Bicycle drivetrain part Machine Bicycle
 

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Elitest thrill junkie
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I remember when we ran chainguides before NW and clutches that chain jams were semi-frequent. Got better when e13 came out with their stuff and MRP then came out with some very similar setups, still happened, but much more rare. I can see the need for bash guards, but I can count on my hands how many times over 6 years I’ve had chains come off, less than the number of jams for sure. When they did come out, the e13 stuff was the bomb for guides.
 

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Do you have an incredibly strong right leg?

Wondering if your power stroke flexed the bottom bracket enough to push the chain into the guide and then to the side of your ring lifting it back into the guide thus jamming the chain and breaking the tooth.

That sucks, glad at least you're ok.
 

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Discussion Starter · #4 ·
Do you have an incredibly strong right leg?
Haha I consider myself in pretty good physical shape but I'm around 160 fully geared up so I doubt I was able to flex anything!

Considering it a fluke... but I'm also pretty sold on removing the chain guide because as Jayem mentioned above I can't even recall the last time I pitched a chain anyway. I didn't run a guide on my last 1x Genius and made it many many thousands of hard off-road miles with only a NW chainring and clutch XTR derailleur to make my chain behave.
Honestly, I'd rather lose a chain and have to stop and spend 5 seconds putting it back on than to have it jam up again and not only break equipment but who knows how I'd come out next time
 

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Discussion Starter · #6 ·
The chain guide is adjustable and has a few marks indicating where to place it depending on chainring size but as luck would have it I had to remove it to get the old ring off and didn't specifically take note of where it was. I'm 99% sure it was placed where they say it should have been mostly because I had to remove it to get the ring/crank off
 
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