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).

 

[silva]

Or, y’know, just replacing the chainring?

Well if you file the hooks off then after that you need to just do nothing, which is less work than replacing, y'know. See it as an investment, that's losing something to win more.

I'm now riding with a rear cog with 13 of its 16T broken off in the middle, and my hope is that by the time the last 3 broke too, the valleys between the teeth will have deepened to compensate for the broken off part.
Then I can continue using the cog until the chain links start to void the mount bolts.
With the money saved by not replacing I can then buy 6 kg potato chips and think about you while crunching them.

 

[Ajax Bay]

Well if you file the hooks off then after that you need to just do nothing,

Look at the image the OP shared. The teeth are fine: no hooks.
And btw, the OP, having joined CycleChat and posted, has never returned (5 days later) so will not benefit from the advice above / thread.

 

[Way-Out-West]

Look at the image the OP shared. The teeth are fine: no hooks.
And btw, the OP, having joined CycleChat and posted, has never returned (5 days later) so will not benefit from the advice above / thread.

In his first post before editing it, the OP stated he had bought the bike second hand and was/is asking how the damage could’ve happened. Answer: it could’ve happened when the previous owner had a chain-suck incident, with old worn chainrings that are no longer fitted, or possibly with those pictured.

 

[silva]

Look at the image the OP shared. The teeth are fine: no hooks.
And btw, the OP, having joined CycleChat and posted, has never returned (5 days later) so will not benefit from the advice above / thread.

Btw I didn't react on the thread starters picture, I reacted on Way-Out-West's picture and the chainsuck problem description, with my post next in the thread.