Talk Composites - The Forum for Advanced Composites

Repair of cracked carbon bicycle frame

http://www.talkcomposites.com/Topic23508.aspx

By adzpz - 6/15/2017 4:07:45 PM

I'm after some advice on the best way to repair a cracked carbon bicycle frame.

As a newbie to carbon layup, I'm planning on a wet layup method and any advice or tips would be greatly received.

One of my queries is how best to tackle all the various angles when laying the carbon fabric onto the frame (see attached image)? 
By mikeyg - 6/23/2017 9:30:33 AM

Are you sure the carbon is broken? and to what extent? I would probably start by removing some of the paint to check if the carbon is damaged. Carbon bikes take quite a lot of abuse before breaking properly, hitting potholes, stone hits etc. Your seatube looks like its broken under the stress of the clamp bolt, and assuming you still have a good 15cm of seatpost in the frame, it might be fine without any repair.

If you still plan to repair it then I would recommend trying reinforce the seatube against the stress the clamp bolt is applying, by creating a ring of fibre around the tube. I.e. dont worry about putting repair material where the crack is.

The way i repair stuff:
  • Degrease/clean everything (i.e. seatpost removed)
  • Strip back paint to carbon by sanding leaving course grit surface to bond to
  • Degrease again
  • Block up, mask areas you dont want resin (e.g. seatube inside)
  • Apply repair material
  • Compact and cure
To compact it, I would keep it simple and use strapping tape.

I would probably just use UD fibre or Biaxial.