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Help! - Unusual chain drop

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Help! - Unusual chain drop

Old 03-02-20, 07:08 AM
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Plungeman
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Help! - Unusual chain drop

I'm running the stock 105 2x11 groupset on an Orro Terra (rigid gravel frame). I'm sporadically (half a dozen times in 7000k) having the chain drop inside the small ring and get dragged up behind the crank (similar to a chain suck, but off the ring). Thanks to geometry of the frame, it's a crank off job to get it back out without damaging the frame or chain - so a touch frustratingly I've taken to carrying the plastic removal tool with me on most rides. This is normally happening whilst shifting at the FD (small to large, I might be wrong but I don't recall this happening when shifting down)

Having assumed it was dropping off the top, I've checked FD alignment and added a K-Edge chain catcher. It still falls off, but hasn't come off the top or slipped past the catcher.

Assuming it was a "flick" from the RD, as it has dropped on rougher ground, I swapped that for a GRX with an adjustable clutch.

This morning it dropped again when shifting the FD up on flat smooth tarmac & low loading.


Any ideas as to the cause? The only certain solution I can think of now is to add a spacer at the front to make it so that the chain doesn't get jammed, but I would prefer to find a proper fix!
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Old 03-02-20, 09:33 AM
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jadocs
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This makes me think that the shift from small to big is incomplete. I would check the limit screw to make sure the front derailleur is shifting as far as it needs while also making sure it does not over shift. Put the bike in a stand and watch the FD closely while making a shift. You should be able to see if it is coming out as far as it needs.
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Old 03-02-20, 11:41 AM
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redlude97
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Originally Posted by Plungeman View Post
I'm running the stock 105 2x11 groupset on an Orro Terra (rigid gravel frame). I'm sporadically (half a dozen times in 7000k) having the chain drop inside the small ring and get dragged up behind the crank (similar to a chain suck, but off the ring). Thanks to geometry of the frame, it's a crank off job to get it back out without damaging the frame or chain - so a touch frustratingly I've taken to carrying the plastic removal tool with me on most rides. This is normally happening whilst shifting at the FD (small to large, I might be wrong but I don't recall this happening when shifting down)

Having assumed it was dropping off the top, I've checked FD alignment and added a K-Edge chain catcher. It still falls off, but hasn't come off the top or slipped past the catcher.

Assuming it was a "flick" from the RD, as it has dropped on rougher ground, I swapped that for a GRX with an adjustable clutch.

This morning it dropped again when shifting the FD up on flat smooth tarmac & low loading.


Any ideas as to the cause? The only certain solution I can think of now is to add a spacer at the front to make it so that the chain doesn't get jammed, but I would prefer to find a proper fix!
Do you mean from the small ring to the big ring? It fell off on the inside? Where on the cassette were you?
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Old 03-02-20, 11:57 AM
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Originally Posted by redlude97 View Post
Do you mean from the small ring to the big ring? It fell off on the inside? Where on the cassette were you?
+1 on this line of inquiry. If you wait until you are on the largest cog to shift to the small ring, that increases the chance of a chain drop. It's generally better to shift to the small ring while you are still somewhere in the middle of the cassette.

Proper setup minimizes the chance of a chain drop, but best practices when riding keep the odds in your favor.
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