Inner Chainring rubbed on frame.. but its not close?

[Danielaaron94]

As seen in the photo, it appears that the chainring on my Wilier somehow rubbed up against the frame enough to take paint off and even scratch the carbon. I am not really sure how this happened since, as it sits, the chainring is a good 1/4 inch away from the frame, and hand cranks nice and straight.

Has anyone seen this before or know how this could have happened? It is hard to believe that a rock got jammed in between the two, but I suppose that is possible.

 

[figbat]

Chain jumped off the ring?

 

[Webbo2]

You haven’t dropped the chain at some point.

 

[fossyant]

A dropped chain will cause that. Worth getting a chain catcher on carbon bikes, or bikes where you want to protect the paint.

 

[Danielaaron94]

You haven’t dropped the chain at some point.

Sorry guys im still new to cycling. So you're saying at some point the chain came off the chainring and was jammed in between, right? This has not happened to me since Ive owned it, however I bought it second hand. Perhaps I just missed this while I was checking it out before buying.

 

[Webbo2]

It’s possible that the chain had come off before you bought it and damaged the paint. Then the paint flaked off later.

 

[Way-Out-West]

Damage like that is usually caused by chain-suck.

Quote:

WHAT IS IT ?​

‘The chain fails to disengage from the bottom teeth of a front chain-ring ; instead the teeth carry it up and around the full circumference of the ring, to wind back onto itself, and to jam between the chain-ring and chain-stay. Because it usually occurs during forceful pedalling, the chain can become permanently twisted, teeth can be damaged, and chain-stays of aluminium or carbon-fibre also damaged by the chain being wedged hard against them.’

I find it’s most likely to occur when the large chainring is worn and the teeth wear into a hook shape (shark fin).
Helicopter tape can help protect the chainstay to some extent.

 

[Ajax Bay]

Chain suck, once upon a time
https://www.cyclechat.net/threads/rear-wheel-lock-up-mystery.288675/

 

[silva]

What about filing off (alu) or machine-grind off (steel) the roller-disengagement- hampering/blocking hooks of the teeth (and while on it anyway maybe also the sideways burrs on the other edge, engagement, of the teeth) ?

 

[figbat]

What about filing off (alu) or machine-grind off (steel) the roller-disengagement- hampering/blocking hooks of the teeth (and while on it anyway maybe also the sideways burrs on the other edge, engagement, of the teeth) ?

Or, y’know, just replacing the chainring?

 

[Ajax Bay]

The OP is not getting chain suck. This is an old injury, before their time. @silva the picture is an illustration used by @Way-Out-West , not the OP's chainring (they are not on Campagnolo).