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Discussion Starter · #1 ·
I was out for a ride today, and was just on regular streets heading to the hills. I downshifted my front derail to the inner most gear. so from 2 to 1. and the chain dropped from 2 to crank shaft..... and wrapped around the inner crank shaft. I tried to replicate the issue and was not able to make it happen again. Everything seems properly adjusted and is shifting correctly. I double checked all of the gears and adjustments after the ride.

So do these things just happen once in a blue moon.
Could it have been my pedaling consistency at that moment?

Thanks
 

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mbtr member
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sometimes **** happens, sometimes your low limit screw on your front derailleur has backed out from the derailleur bonking it, or it was never set correctly in the first place.
 

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As they said, sometimes it just happens - who knows why. But it'd be a good idea to check the low limit screw on the front derailleur just in case - the chain should, oh so lightly, rub on it when back pedalling in granny-granny; Once you are actually pedalling it won't rub though.
 

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No that shouldn't happen. I had that problem earlier this year and I solved it by adjusting the limit screw. I had that happen to me in a race and I smashed my knees into the handlebar or the headset area. I can't remember which, but it hurt. I suggest you get it fixed before you have the same experience I had.
 

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Clarity...

Rod said:
No that shouldn't happen. I had that problem earlier this year and I solved it by adjusting the limit screw. I had that happen to me in a race and I smashed my knees into the handlebar or the headset area. I can't remember which, but it hurt. I suggest you get it fixed before you have the same experience I had.
It shouldn't happen on a regular basis (every ride) but it will happen from time to time based on multiple factors (gear, trail conditions, riding style, etc) regardless of whether your limit screw is adjusted properly or not.
 

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Probably drunk right now
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Right...

dan0 said:
for no reason, no. There is always a reason, limit adjuster, bent tooth(teeth), tweaked chain, bent, damaged, or miss aligned dérailleur to name a few
Or you ride over some rocks, your derailer moves and the chain drops. It happens sometimes. If a chain drops on me, I don't spend any time trying to figure out "why" and just accept it as part of the sport. On the other hand, if a chain drops more than once in a ride, there's usually a reason and I try to find out why.
 

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local trails rider
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It does happen. Some want to make sure it never does and install something like an N-Gear Jump Stop, to make sure the chain will not fall off on the inside.
 

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It shouldnt happen, unless your riding really hard.

could be your lower limit screw. Or it could be from too much heavy lube on your chain. If you have alot of lube on your chain whipe it down. This happend to me after I took my bike to the shop for maintenance. They told me "it just happens" I asked another bike shop and they told me (without seeing the bike) to wipe down the extra greese on my chain.
It worked!

I would recomend rock-n-roll lube to eliminate this problem
 

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a slightly bent ring will do exactly that. you have to shift when your crank is in the bent spot and it'll toss it over the ring, so it wont do it all the time, but as the bent ring gets worse it'll happen more frequently.

keep an eye on it, if it starts tossing the chain more often when shifting, and your limit screw is fine, you probably killed a ring.
 

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I like bacon... (clyde)
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The only time I've had mine fall off is during a bad shift, i.e. downshifting in front under load at low speed (while going uphill). There is a balance in the low limit screw here. You have to keep the inner side of the cage as close to the small ring as possible to prevent fall-off and give you as much non-rubbing access to your cassette as possible but still have enough of a gap so that the outer side of the cage can quickly and easily knock the chain off the 2nd ring.
 

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Dirt Deviant
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It also depends what gear you are in on the rear. Other factors like frame flex could make it happen as well. Especially if you are a heavier rider.
Most likely it was just a fluke, unless it starts happening alot.
 

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local trails rider
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There's one situation where I used to occasionally drop the chain: hitting the bottom of a short but steep uphill as fast as I could manage in middle ring, and then trying to shift to granny ring before I lose momentum. Then there's some bump just when the chain is "in the air"...

Shifting in the front seems to be much less predictable than in the rear: it is a pretty big move for the chain.
 
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