dimples on carbon frames

[aclinjury]

Every month or so, there will be a post regarding this.
And from just observations, these dimples seem to be along the the seat tube area, but could be at other areas too, even at the fork.

So are dimples a fact of life with carbon frames? And what could cause them? Is it inherit in the manufacturing process?

PS: I don't know about yall but if I paid top money for a frame and there are dimples (even though them dimples don't affect structural), they would still be eye sores somewhat!

[esldude]

I have seen some pretty high dollar bikes with the dimples you are describing. Or at least I think you are. Are you referring to bubbles or imperfections usually in the clear resin layer?

As much as people here sometimes malign them, I think Trek carbon bikes show less of this than other brands in those bikes I have seen.

[Kerry Irons]

Every month or so, there will be a post regarding this.
And from just observations, these dimples seem to be along the the seat tube area, but could be at other areas too, even at the fork.

So are dimples a fact of life with carbon frames? And what could cause them? Is it inherit in the manufacturing process?

PS: I don't know about yall but if I paid top money for a frame and there are dimples (even though them dimples don't affect structural), they would still be eye sores somewhat!

If what you are talking about are those paint blemishes, they are often called blevs or fish eyes. Purely cosmetic though not something that should be part of a good paint job. I fixed that issue when I went to a Ti frame but I never saw it on multiple paint jobs on multiple steel frames back in the 70s, 80s, and 90s.

[aclinjury]

@esldude
I know what you're talking about, the clear bubbles. But not what I was referring to. But bubbles are another fact of life with carbon frames. I have never seen a carbon frame that does not have bubbles in the clear coating.


@Kerry:
I'm talking about actual depression on the carbon, a depression that you can visibly see and feel. It's more than an imperfect paint job.

[mann2]

when i got my first carbon bike, a supersix hm, it was flawless. after a couple of years, some ripples/dimples started appearing on top of the headtube. this seemed to be formed from stress on those parts. not at all like paint imperfections.

when i got a scott foil, same thing appeared and in the same general area. seems normal to me. no ill effects on performance whatsoever.

[mikerp]

So are dimples a fact of life with carbon frames? And what could cause them? Is it inherit in the manufacturing process?

PS: I don't know about yall but if I paid top money for a frame and there are dimples (even though them dimples don't affect structural), they would still be eye sores somewhat!

Based on what I've seen carbon frame manufacturing wise, I'd say it is part of the general process used.
When using "pre-impregnated" carbon lay up vs. a vacuum resin process.
IE while the "pre-impregnated" carbon process (place cut layup pieces in a mold with a bladder apply pressure and heat) creates a part with a general shape it does not guarantee a 100% mold line interface.
The options are:
* leave it as is
* fill it in - the fill could drop out in the future, adds weight, and manufacturing effort ($$$)
Which would be your preference?