Carbon Bike Repair

[Mark Christensen]

I am going to repair a small injury on my very expensive Santa Cruz Carbon Fiber Bike.  I am looking to find information on what type of Carbon Fiber I need to get, how many layers and any other insights anyone may have.  I have watched the videos and read up on it and it seems if you follow the directions, don't deviate its a very doable  process especially if you use shrink rap tape and a heat gun to finish the laying of the carbon.   Thanks in advance and looking forward to people chiming in.  Mark 

[John Kimball]

14 hours ago, Mark Christensen said:

I am going to repair a small injury on my very expensive Santa Cruz Carbon Fiber Bike.  I am looking to find information on what type of Carbon Fiber I need to get, how many layers and any other insights anyone may have.  I have watched the videos and read up on it and it seems if you follow the directions, don't deviate its a very doable  process especially if you use shrink rap tape and a heat gun to finish the laying of the carbon.   Thanks in advance and looking forward to people chiming in.  Mark 

Bike repair is a very fluid topic as each injury and subsequent repair will be based on the location and severity of the damage. Your frame is most likely made from unidirectional carbon fiber prepreg, but repairing with a similar material would require special equipment to cure the prepreg. There are professional outfits that provide this service, but the typical DIYer won't be able to do this.

In your situation, it sounds like you have minor damage on a tube section. If that's the case, you would need to remove any paint from the surface, prep the surface for bonding, then use a dry woven fabric and 2 part epoxy resin or adhesive to cover the damage. Using shrink tape will give good consolidation and help with the cosmetic finishing. The number of layers depends on the size and extent of the damage.

Posting a picture of the damage will help us provide better feedback.

[Mark Christensen]

[lo_0l]

Hey @Mark Christensen,

That actually doesn't look too bad, but @John Kimball is the expert here. He could correct me if I'm wrong, but I'd probably just cut off the rough bits, give it a quick sanding and a shot of paint. Otherwise leave it alone.

We've actually got a DIY guide on how to make a rock guard for your bike to prevent things like this in the future:

 

 

[John Kimball]

On 11/3/2022 at 9:45 AM, Mark Christensen said:

Mark,

That isn't terrible, but there could still be some hidden damage (delamination) lurking below the surface. Removing the fractured fibers will reveal more. But in this case, you may just want to remove any burrs or slivers, sand the paint away and apply a single layer of woven carbon fabric/epoxy resin over the area. Overlap the fractured area by about 1" on all sides. Use the shrink tape to get good compaction. The resin will weep into the wound and somewhat prevent the fracturing from propagating further. Kind of like a windshield repair. Not perfect, but adequate. 

Otherwise, a full repair would require specialized sanding and layered patches to repair the area. You can use a quarter to perform a tap test to see how far the fracture is under the surface. Tap the quarter in an area that you know isn't damaged and then compare the sound to the damaged area. A good laminate will have a sharp "ping" sound, where delaminated areas will have a "thunk" sound.

[Mark Christensen]

Thanks for all the information I feel confident that this it the correct route for keeping my bike up and running.  Looking at the different types and thicknesses I'm not sure what to purchase, also where is the best place to get epoxy in small amounts.  I will be fixing this in early December.

Again.... 

THANKS

[Mark Christensen]

One more Question, when I am finished where would I get the appropriate paint to finish the job???

[John Kimball]

On 11/12/2022 at 1:30 PM, Mark Christensen said:

Thanks for all the information I feel confident that this it the correct route for keeping my bike up and running.  Looking at the different types and thicknesses I'm not sure what to purchase, also where is the best place to get epoxy in small amounts.  I will be fixing this in early December.

Again.... 

THANKS

Rock West does sell sample packs of West System 105/205 that come pre-measured pouches for easy use. This is really fast curing, so you need to work quickly and deliberately.

https://www.rockwestcomposites.com/shop/materials-tools/resins-adhesives/101-t

[John Kimball]

On 11/12/2022 at 1:49 PM, Mark Christensen said:

One more Question, when I am finished where would I get the appropriate paint to finish the job???

You may need to contact the bike manufacturer to get that info. Any automotive paint should fine, but matching colors and finish will be super fun.

[John Kimball]

On 11/12/2022 at 1:30 PM, Mark Christensen said:

Thanks for all the information I feel confident that this it the correct route for keeping my bike up and running.  Looking at the different types and thicknesses I'm not sure what to purchase, also where is the best place to get epoxy in small amounts.  I will be fixing this in early December.

Again.... 

THANKS

Also, You can use either 3k plain weave or 3k 2x2 twill for the fix. I'd probably prefer the plain weave for this application. Check our dry fabrics samples for the material you need.