Bike Forums - View Single Post - Big hole in top tube of new bike (Pics attached) aluminum repair with carbon fiber

11-22-20, 05:53 PM

#59

vespasianus

Senior Member

Join Date: Jul 2019

Location: In the south but from North

Posts: 700

Bikes: Turner 5-Spot Burner converted; IBIS Ripley, Specialized Crave, Tommasini Sintesi, Cinelli Superstar, Tommasini X-Fire Gravel

Mentioned: 0 Post(s)

Tagged: 0 Thread(s)

Quoted: 406 Post(s)

Likes: 746

Liked 389 Times in 219 Posts

Quote:

Originally Posted by Yellowlab

Part 2

Step nine: Sand first carbon treatment to desired look. I tried to keep as much of the original shape as possible without sanding off enough to compromise the structural integrity of the carbon fiber.

Step ten: Wash, rinse, repeat steps seven through nine for second carbon fiber wrap. The first wrap was about 6 inches wide, this second one was about 11 inches wide, again with thinner edges and getting thicker towards the middle to maintain a tapered look. The first 6 inch wrap was 4 layers of carbon. The second wrap was three layers as I ran out of fiber but there are a total of seven layers directly over the damaged section which should be plenty.

Step eleven: Again, wait a full day and remove tape to sand to desired shape. At this point once I had the basic shape, there was still a couple of "pits" here and there and I wanted a nicer finish so I took the time to apply two more coats of just epoxy during the next two days, over the final sanded layer of carbon fiber.

Once the final two layers of epoxy cured I sanded the final product down 400 grit sandpaper. If I was going for an actual carbon fiber look I'd probably get down to wet sanding with 800 grit but I'm just going to paint it clear so I can continue to have a visual on the repair and see if there are any potential issues popping up with it in the future.

Nothing can be done to prevent the fact that seven layers of carbon fiber and a layer of fiberglass will inevitably add a visible bulge to the fixed area that can be noticed upon closer inspection.

So that's it. The total cost of materials for the fix was about $70. It's mostly just a lot of time and elbow grease but I think it was worth it to not scrap the frame. There are still a couple of tiny pits that aren't perfect. I may or may not fill these with some bondo before painting. I wasn't originally going for a perfect aesthetic looks so much as I wanted to ensure a competent structural fix that will keep the bike safe to ride for years to come.

Let me know what you think or if anyone here has any experience with this type of fix and did it hold up.

Thank you!
Cliff

I have no experience with that type of fix or the durability of such a repair but I still say well done! I admire the spirit and work performed for the repair.

Reply