Scratch on carbon bike frame

Scratch on carbon bike frame DEFAULT

Post by RawrCalon Fri Jun 12, 2020 12:34 pm

Hi there, I finally registered an account on WW because I feel I can help with this issue. If you are just looking to conceal, I have a much simpler option for you to consider.

I have a 2019 Sworks Venge in matte black/holo with matte black CLX64. So obviously everything is matte black. I am also an obsessive bike cleaner so I am examining my bike pretty often.

I went through a weird thing with this venge where I ended up scratching up the rims of the CLX64disc a lot (whether I accidently knocked it over, or dragged it next to a curb) and it looked terrible afterwards. Lots of white jagged streaks just like in your photo and I was heartbroken because it was an eyesore. My wife felt bad for me and even offered to replace the wheels with something else of my choice (I should have taken her up on it).

But like you, I just wanted it to be not so obvious from a few feet away. I knew a "repair" wasn't something I was likely going to pay for nor do myself in any effective capacity.

So here is what I did. What you need is a black paint tip sharpie (attached) although a regular sharpie will do. Also, isopropyl rubbing alcohol and a paper towel (or clean microfiber rag). It is rather simple: you take that sharpie and just fill in the scratch (after you make sure it's surface cleaned and dried with some alcohol on the paper towel). Get the tip in the groove and fill it in best you can until it's all black. The paint pen sharpie I used is a little better for this since when you push the tip in during use, it will release more liquid ink/paint compared to how a regular sharpie marker works. You will also unavoidably get sharpie all over the surrounding unscratched portion of your black matte frame, which will look bad. Once you have filled in the scratch, you then need to remove the surrounding unwanted ink/paint on the frame. Take your paper towel (or rag), pour some alcohol on it, and then wipe over the affected area until the extra paint/ink on the frame is removed. This method effectively removes the surface unwanted ink from the frame while leaving the ink in the groove created by the scratch. Thus in the end it is a filled in scratch that will become nearly unnoticeable unless you are looking for it. This is not a miracle "fix" though, again it just makes the scratch black, the scratch is still there and can be seen/felt if looking closely.

Hope this was helpful. If you are skeptical, I would try a smaller, less obvious scratch before attempting the big one. Remember, this black ink/paint should remove with alcohol so the risk of creating a larger blemish is low and you can just remove it all if you dont like it. I recognize too that I have not had to do this with my actual matte frame yet (only wheels and seat post) so I recommend using your sharpie under the BB and try to remove with alcohol to confirm that the ink does comes off the frame effectively. (I have attached a few photos from my "fixed" rim scratches)

Best of luck!

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Small cut/scratch in carbon frame...

Originally Posted by humboldt'sroadsView Post

Ok - so I checked it out under better light...I mean, the cut is 1/2 inch long at most, and looks like it went through paint, but I don't see anything that's obviously a fiber, but the cut really is too small to tell. I can tell that if any fiber got cut, it wouldn't be more than a millimeter or two and one layer thick, and that's a big if, from what I can tell. At this point, I can't afford a new frame, even an aluminum one, so I think I'm gonna ride this and see if it makes any noise and see if the clear coat cracks any.
Further opinions?

Ride it.

Okay a short tutorial on composites. We have been building metal airplanes for 85 yrs and composite ones for 25.There are several types of non destructive inspections you can do for metal (dye penetrant, X-ray, eddy current, etc) but very few for composite structures. Ultrasound is about the only game in town. Also our capability to model composites' behavior under various loads is still in it's infancy. Especially a complex shape.
As a result for aircraft applications (and I suspect bike frames) composite structures are grossly overdesigned. (spacecraft are a different story then most aircraft structures because they will except lower margins to shave a few pounds) If the resin fiber matrix can carry load X, we typically design to twice that due to the uncertainities involved.
How these things typically fail are void propagations between layers, ; i.e. delamination, followed by failures of the layers themselves . Think phone book. No one can tear a whole phone book in half but a toddler can destroy one a few layers at a time once it is "delaminated". Failure across intact fiber layup, i.e. cracking simply never happens unless the loads are horrendous.
So if you want to have a warm fuzzy then get a quarter and do a "tap test". This is what we do with really really expensive composite aircraft structures before we untrasound them. You can actually map the edges of a void pretty well with a quarter. Once we know there is a void we will mark the edges after an ultrasound and check it periodiaclly with a tap test to make sure it isn't growing. Tap the edge of the coin along the frame and it should have a nice crisp click noise in response. If it clunks instead of clicks then that means there is a void underneath. Since the BB and tubing are hollow they will have a drum like response to a degree but a real void sounds sorta dead. Assuming you have had no voids propagated yet, tap the suspect area and listen. Do this occaisionally and as long as it keeps clicking then you are fine. Even if it starts clunking you can probably ride it a very long time before it falls apart.
Yes composite frames fail. Poorly designed, poorly built frames of all kinds fail. But if a composite structure doesn't fail in it's infancy they usually live forever unlike aluminum or steel.
Remember Orville and Wilbur started off building bikes...
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Scratched carbon frame - any recommendations?

So it was scratched on a rock, do not think there is any actual structure damage on the frame, as the bike just scrapped the rock, as it was knocked. I called Intense in the UK, they suggested a car body-shop for repairs, which was quite surprised with.

Any recommendations, ideally around home counties area for a repair?


Which side of the Home Counties? I had some car bits done at TGM Sport in Fleet and the paint shop guy there (Will) does all sorts of things (very high end stuff including carbon fibre), and I get the impression is a perfectionist and if he'd be interested in doing a bike frame it would be an incredible job.

Leave it?

It's an MTB & will happen again. It's not going to rust.

As above.

I went to Antur Stiniog last week on my brand new carbon Cube...some horrendous rock hits and a mild no longer looks brand new, but that's what it's for eek

Too late now, but invisframe would have probably saved that

Freakuk said:

Too late now, but invisframe would have probably saved that


Ignore it. Seriously it will cost a fortune to have it painted, which will also void the warranty. Its a mountain bike, they get scratched. If you care, you should have invisisframed it before the first ride. I'm not being arsey, I genuinely think that's probably the best advice.

I had my road bike blow over in the wind and hit a wall. That took a chunk out of the shiny red paint on a seat stay down to the white primer/undercoat?

I "fixed" it with a blob of my wife's nail varnish. It's the wrong red, but it's less obvious than a big white chip out of the paint. I was going to wheel the bike into Boots or Superdrug to match the nail varnish to the paint, but life's too short for being that fussy.

snotrag said:

Ignore it. Seriously it will cost a fortune to have it painted, which will also void the warranty. Its a mountain bike, they get scratched. If you care, you should have invisisframed it before the first ride. I'm not being arsey, I genuinely think that's probably the best advice.

Have much is a fortune please? Bike is outside warranty, no concerns there.. If I didn't care, why am I asking for recommendations for places to repair it?? Your best advice is Invisiframe, but this not what I am asking for?? That advice would great after getting it fixed.. Don't think you are being arsey..


Have you tried any of the car smart repair places?
A lot will give a yes or no and a price with a picture of the damage. I guess its just if they can match the colour well enough.

I had a look at some invisiframe but didnt like it so decided to use the thicker 3m stuff on a roll and put it on in select places. Easy to replace a section if needed. Not sure if they do a matt version though.

james7 said:

Have you tried any of the car smart repair places?
A lot will give a yes or no and a price with a picture of the damage. I guess its just if they can match the colour well enough.

I had a look at some invisiframe but didnt like it so decided to use the thicker 3m stuff on a roll and put it on in select places. Easy to replace a section if needed. Not sure if they do a matt version though.

Yes, tried a few smart repair places, they are not interested. However a specialist company has come back with a quote of £120+vat, which I may consider, will continue to shop around.. Quite a bit of hassle, as many of them want you to strip the bike down with just the frame sent in..


Wooderson said:

These are the people to go to....but they aren't cheap


I had this repaired on my Demo 8. I dont have an after pic to hand but it was an invisable repair and they blended and matched the matt red and pearl black perfectly. Was around £180.

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Quicktips - Don't do this to a carbon frame!

Carbon fiber fork scratched. Paint over or replace?

I wouldn't pitch the fork just yet until you get a professional assessment at a bike shop. You could gently tap on the fork for several centimeters around the wound and listen for a change in the quality of the tone nearer the scratch. If present I wouldn't ride until a better assessment is completed. That said, neither would I call this little test reason enough for comfort if nothing was heard.

Here's an interesting trick I recently read about. Apparently, helicopter mechanics use this technique to fill/repair chips in rotor blades. If one takes liquid cyanoacrylate glue ("super glue," "Krazy glue," etc.) Fills the basin of a scratch or chip and then immediately sprinkles a generous coating of baking SODA onto the wet glue, it dries and hardens in seconds. The resulting dried cyanoacrylate-baking soda filler is extremely hard, sandable and paintable.

I've used this trick when I want a super glue application to be dry almost immeadiately. An improvised chain tool pin I fashioned from a screw tip bit has been held securely within the threaded pusher of the tool. Still solid after a half-dozen chain breaks

answered Jul 26 '19 at 1:56


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Carbon bike frame scratch on

A slight scratch on my Cervelo top tube.
A slight scratch on my Cervelo top tube.

Yesterday, on a long ride with my best friend, I was having a bit of trouble with sore legs. So I decided to unclip and pull my foot up over my top tube to stretch it . . . I know, it’s starting off bad. As I slid it back down, happy with showing off, my cleat just scraped the edge of the top tube and put a set of dimpled scratches right into the red stripe of my carbon frame. Ignoring the lesson about being a show-off, I tried in desperation to buff the marks out with my fingers, but no luck. I learned something in the exchange: always keep your hand under your cleat when pulling such an awesome trick like stretching on the top tube. 😉

How do we repair small scratches and chips in our frames? First, do a close inspection of your bike–top to bottom–and look for cracks or deep scratches. If you see anything that looks a bit sketchy, take it into your local bike shop and ask the mechanic to take a look. He or she can make sure you don’t have any structural damage. It’s always best to make sure everything really is just cosmetic. If you do have serious damage, your frame can probably be fixed as well–simply ask your LBS for a local frame guru who can repair it.

Fixing That Scratch

Depending on the ferocity of your scratch, and the level of your resolve to repair it, you have a couple of options for getting that shine back.

First, you can take the easy route and simply cover the scratches with a clear coat to protect them. Some use high-quality, chip-free nail polish clear coat such as CND Speedy Clear Coat. Just paint a layer or two of the polish for a quick, easy, and no-effort protective coating for your carbon. You can also try to match the paint color in a high quality nail polish–so long as it’s enamel, it should work just fine. The difficult part here is getting the proper color match, and painting it without letting it glob up. I recommend using a better brush than the one in the polish bottle. If it looks rippled, you can use a very fine buffer to shine it up and smooth it out.

If you feel a bit funny about putting nail polish gloss on your frame, you can also use Testor’s Glosscote spray, which is manufactured for model builders to seal in their decals and add a glossy shine. Before spraying the area, make sure you mask and cover everything you don’t want coated! You’ll be surprised at how wild this stuff can spray–and it can be tough to get off of places you didn’t intend on coating. Of course, your bike may not be a high-gloss finish–in which case, look at Testor’s other options in clear coats.
For Tougher Scratches/Chips

You’ll probably want to sand the area smooth before coating it with anything. Try wetsanding the area with a fine grit paper. If it’s a tough scratch, use a progression of rough to fine grit papers like 240, 400, and 600 on up to 1000 until you can’t feel the difference between the damaged and non-damaged areas.

It’s vital to keep everything clean! Make sure you don’t have residual dust, grit, or other things in the area you’re fixing.

Unless you’ve got a fairly large chip in the frame (in which case you’ll have to deal with primer and putty and stuff that’s beyond my experience-level), you should be able to get away with simply finding a matching paint. Go to your local automotive store and find the closest match you can find. With all sorts of colors of cars, they should have one that will blend in perfectly with your paint job.

Fill in the missing paint area, let it dry and sand at your own discretion (in case you’ve got spots that need it), and you’re on to the clear coat. If you need to do any layers of paint before that, make sure to sand between each, and let them dry completely before adding the next coat. The key here is to get a smooth finish without having a noticeable shift between the fixed area and the original paint. You can use a nail buffer to get a really smooth finish on the top, then add another coat of clear gloss.

Et voila! Your bike should look back to normal. Make sure to let it dry completely–like for a week–before putting it through the wringer on a weather-torn day.


Tried this method and it worked well for you? Have some tips you’d like to add? Need clarification? Comment below!

Disclaimer: Complete all repairs at your own risk! I’m not responsible if you mess up your frame/bike/components/wheels using this method. Above all else, please be careful!

How to remove scratches on your carbon bicycle cranks - for the home mechanic

Especially do not expose yourself, the blanket. Was left for you easy, you will freeze. - With you, so hot, and freeze. I say, taking off my boots, then its the turn of the jacket, trousers and tie.

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