bblair

The first ding on a new bike or car is actually quite liberating. You now have a used bike so go out and enjoy yourself. You will get worse chips from flying road debris and when your bike invariably falls over in the parking lot when you weren't careful.

Or.....you could do like I did: get a titanium frame with no paint and never worry again.

vane171

You can do the tap test on the opposite side of the chainstay tube but as has been said, most likely it is just a cosmetic damage. The tapping could just detect the paint surface tension which has been compromised in just that spot, maybe 1/8" area it might have lost adhesion to the CF, which itself is very likely undamaged.

For peace of mind, I'd put on drop of clear lacquer (that you can get in any car autobody supermarket section) to seal potential hairline cracks right where the dent is, so moisture can't penetrate the paint and ride it without worry.

hokiefyd 

This is what I was thinking as well. With the localized contour of the paint different in that area, and given a small enough detection device (small enough bar to tap with), it's almost certainly picking up that difference in the density or other physical characteristic of the paint. I would think that damage to carbon fiber (a material that, by definition, gets its strength from a collection of fibers weaved together over a certain distance) would be much less localized than just the one very tiny paint spot. In other words, true structural damage would probably be detectable over a larger area.

SoSmellyAir

Sorry, it is hard to tell if someone is joking on the Internet. In my humble and unlearned opinion, I doubt that the structural integrity of the frame is compromised. The impact may have sounded loud, but the tool that hit the frame was light weight and the distance to impact was low, meaning that your friend did not have much time (over that short distance) to accelerate the tool to hit the chain stay with that much force. (Force = Mass x Acceleration.) If you are concerned, you can put your lips on the chain stay at that spot and suck on it to see if it is still air tight or whether the tool has penetrated the surface. Yes, I am just kidding.

Mosman12

I took another look and noticed with a flash light a shadow hairline scratch (not sure if it is a crack or not) just next to the initial impact point and running along the chainstay. Any thoughts if we are looking at anything more than a paint chip ?

cxwrench

Go. Ride. Your. Bike.

Iride01 

If you live close by or somewhere between here and Denver, I'll pick it up and ride it a few years and let you know if it's a problem to worry about. I can return it on a subsequent trip if my son doesn't move elsewhere.

Seriously though, you have two choices, ride it and watch for further issues, like the current "maybe it's a crack" actually becomes a crack. Or take it to a carbon fiber bike repair place.

Okay, maybe there is a third option, just don't ride.

squirtdad

I am not a huge fan of carbon, but even I don't think it is that fragile.

based on all the posts I don't think you are ever going to be comfortable with a carbon frame. If you worry about every chip, you will never enjoy the bike
I suggest getting a nice steel frame, whether vintage (vintage steel and modern gear is a great combo) or new (they are out there)
Sell the current frame, show the buyer the chip full disclosure and take 50 bucks off.

or talk to one of the frame repair companies, but I think that no matter what your are always going to be not comfortable with carbon

gearbasher

My guess: After the Allen hit, it slid along the face of the stay and put a light scratch in the top coat.

vane171

That's also what I thought of that light scratch. Also could have been there due to another prior handling.

The OP could also take a close up picture with camera at macro setting and with as high resolution he can get, under different lighting from a lamp, a flashlight or with camera flash and under different angles (camera flash at close distance doesn't always work well). Close up pics take few tries to come out good but if you manage, they show what you can't quite see with your eyes. On the other hand, such macro pics can scare you, things that looked so nice when looked at with your eyes all of sudden reveal themselves full of dust and scratches.

Atlas Shrugged

For the third time now. Sell the bike, you are the wrong person for a carbon bike. How can you reasonably expect to actually leave the house and ride this bike, lean it against things, pack it for a trip, place in a bike rack and yes eventually drop it. No amount of everyone telling you to just ride the dam thing will put you at ease.

Camilo

I agree. With the small amount of force caused by a light weight crank, spinning at a relatively slow speed for a short distance, and a light weight tool involved (I'm no engineer or physicist, but that's how I would analyze the impact).... how can the OP possibly tolerate the rocks thrown up by his tires and/or accompanying cyclists or passing cars. Or less than gentle leaning against the wall or car, or.... Dings happen. this is a ding.

Mosman12

Took some macro shots. I think the line is where the Allen key slid along the chainstay after impact. In the point of impact I already see tiny bits of carbon exposed, just cover up with lacquer ?

Chuck M 

One of my other hobbies is home brewing beer. Before I started brewing I was bored and curious about it one evening and came across an internet forum for home brewing. The stories of everything that could go wrong with a batch made me think brewing would be a PITA and I moved on. Some time later I attended a clinic at a local home brew shop and saw exactly how easy it is. It turns out, the home brew forum is full of people regurgitating what they have read about the possible bad things that can happen but had no first hand experience. I think this is pretty much what happens with posts about possible carbon fiber damage. What home brewers eventually learn to do is RDWHAHB, relax, don't worry, have a home brew. Don't let people's anecdotal evidence make you nervous as a hooker in church with a $10 date outside.

FWIW, I don't have a carbon fiber frame, but I have a carbon fiber fork. The appearance of the scuff from laying it down at approximately 20 mph and the scratch from it falling over while washing it bother me more than possible structural damage.

RDWRYB, relax, don't worry, ride your bike.

bOsscO

While scrolling twitter this morning I found this pic of Steven Kruijswijk Cervelo that he rode the TdF with today. He'd crashed (along with tons of other GC contenders) and damaged his bike. But he managed to get back on it and finish the stage...looking like this.
I know it's just one example (albeit an extreme example) but maybe it can help put the OPs mind at ease. Carbon is stronger than you think.

Atlas Shrugged

We are now fully in troll category and time for me to check out. Hope you had fun exploiting people who had good intentions and wanted to help a fellow cyclist.

Erzulis Boat 

Carbon bikes are strong! I have carbon MTB race bikes that get smacked by rocks super hard. Still fine.

tendency

that's why you have two chainstays worst case scenario it cracks while riding. no biggie it wont cause a catastrophic chain reaction death crash.

i had a buddy who's carbon MTB chainstay snapped while bombing a downhill run - he barely noticed it just said the back wheel felt a little funky. later, after a couple beers he noticed the drive side stay was cracked clean through. sucks for the frame but you're not going to hurt yourself if it fails.

IntraVol

If you saw the condition of my carbon chain stay on my Izalco Max you would literally die then.

xiaoman1 

Lot's of bandwidth used on this.....take it to your LBS that has a lot of Carbon and ask them to take a look at it....the net will only be as good as...well the net, nothing really definitive without actually viewing it in person.
Please visit a shop that can tell you more about the "damage" in order to set your mind at ease.....My best advice.
Ben

spelger

practically need a microscope to see it. i don't have one yet but i find it funny how everyone freaks out about carbon.

EDIT: ok, maybe not everyone.

Eric F 

I have 3 CF bikes. All of them have deeper dings than that, and I have 100% confidence in their structural integrity. My 20+ year old MTB is pretty beat up, with multiple dings that expose the raw CF material under the paint. It rides just as solid as it did when it was new.

CF composite material is carbon fibers buried in epoxy resin. For the material to break, you would need to crack the resin and snap the fibers. You can beat the hell out of the paint and still have complete structural integrity of the composite material. The tiny ding in the pics is a bummer because it's a blemish on a new frame, but it's a LONG way from being structural damage. Go ride your bike.

Eric F 

No, you don't. Even if you did, a tiny bit of exposed CF composite isn't a structural issue. It doesn't leak out.

Mad Honk 

Mosman,
I deal with CF everyday. I am a Golf Equipment Professional and about 90% of the golf shafts are made of CF. I have picked out a specimen that was the tip section of a failed carbon fiber tube. This one was a $400 golf shaft so higher end CF. I intentionally rubbed some of the paint down to the CF underneath with a file. And have pictures of what failure looks like in carbon fiber. From what I have seen in all of you pictures, there is no damage other than cosmetic. The golf shaft breakage in this case was the club being slammed and smashed by a closing trunk. The yield strength of CF is pretty high, a normal golf shaft goes through the impact speeds of over 100 mph every time the CF club is used. Here are some pictures:

The paint is scratched down to the CF which is a black color underneath the paint. There is no damage to the carbon fiber. The paint removal does not damage the fibers underneath.

This is what damaged CF looks like. Note the shards of carbon fibers sticking out from the damaged section.

This is a close up of the damaged CF showing the layers or plies of the CF as it was produced.
I trust this was helpful in understanding CF damage for you. Smiles, MH

shelbyfv

Have you considered wrapping the stay with some epoxy tape, just for peace of mind?