How to repair carbon fiber bike frame? Some tips for you to repair the carbon bike frame and repaint it

How to repair carbon fiber bike frame

With the special qualities, Carbon has its own advantages and shortfalls. We all have to have a  bit of understanding about the nature of the carbon fiber and its structure as well as lay-up. A riding accident will break your carbon fiber frame completely but that is not the end. You need not to discard the broken pieces as they may be repairable in the hands of repairing experts. Some specialists compare the process of repair to the building with LEGO. As for a frame surface carbon fiber frame there is a lot of area to work with. Carbon is much easier to be broken by a crash and the risk is much higher than the steel and aluminium. In general, most things are salvageable.

Lightness and strength | From Lytron bike

It is generally known that the prerequisite for the carbon to bond back into one piece is to have a certain density. According to the UCI standard the minimum weight limit is 6.8kg. As the frame is getting lighter and lighter the tubing is getting gradually thinner. It is the principal factor to create the problems.

When someone is repairing the frame he or she should to make the repair as good as the original carbon fiber frame. To mend the broken part we need to add material. Modern oversized carbon fiber frame has a larger area to attach more new material to it. But at certain area of the carbon fiber frame it is difficult to do the repair, for example, the bottom bracket. Yet there is still another place where is better to perform an operation to prolong the lifespan of the bicycle, for its higher price. Certain expertise and maintanence have something to do with the after-repair period.


Our methods

First, we are not engineers or experts of composites. We are giving you some advice for you to make a quick aid for your bikes. This guide is meant to be a useful tip for you who want to repair your carbon frame at your home. Yet do not try to mend the broken carbon forks, saddles or handlebars and so on. Even the professional repair worker won’t have perfect confidence in repairing the parts at all.




  • preparation

What I recommend for you is the cooperative kit includes a sheet of 3K carbon fiber, a bottle of epoxy and the other hardener,

mold release wax, a professional brush, mixing bottle, and a pairs of gloves.

Not all of them can directly make out the function we desire. We also need to process it to get it in to a feasible and available condition. What’s more we also need a shrink release tape to compress the carbon material to apple it to making the appearance better. It is a highly-specialized kind of tape used in making the composites.




Because we have to dismantle our bikes completely so that I can begin my repair action, it is also a good chance for us to repaint our carbon fiber frames. We have post a detail of repainting the carbon frame before. In addition to the repair kit, here are a few other items that I bought or used for this project. It is depend on your repair process so you are able to take what you need.

For instance: Sandpaper, Dust masks, painter’s tape and some paint.


  • Repair process

  1. dismentle your bike

Completely stripping the whole component of the frame and hang up your frame on the hardware to make the next steps easier.




  1. sanding and clean it

We have to sand down the broken area to raw carbon. In this condition the surface of the carbon is easier for us to adhere the new paint. A piece of wet sandpaper help to roughen the surface of the damaged carbon bike frame.

Don’t forget to clean it completely with alcohol.




  1. masking it

To avoid the escaping of the epoxy we should mask the rest area to get rid of its running around.




  1. Cut Carbon Fiber

We have to cut a small piece of carbon fiber from the template. Take care of it for its loosen situation and you should send it between foil to keep it safer.




5.Mix the Epoxy

We have to mix the epoxy and hardener at the rate of 2:1. For this mixed liquid is only used for the base layer You should only mix fairly really little amount of them. The instruction mentioned we would best to mix them for no less than 5 mins to get their totally mixed.




6.   Apply Surface Coat of Epoxy

The epoxy is applied by a professional brush and after that just aside of it and get it outside to let it dry.

If you want to make the liquid to be tacky the most thing you should do is to make sure that there is no residue on your gloves. It would take about 2 hours to do the step.


7. Lay Down Carbon Fiber piece

If the condition of the epoxy has been at the approximate right level of tack it was the right time to lay down the piece of the carbon fiber.

Before that we should prepare the other pot of epoxy. For the next step I recommend you to prepare about twice or much as the first time. You need to lay down the first patch carefully after that. We all have only one chance to lay down it right to the broken area so it is important for you to be careful. The best part to start it is from the top edge of the patch then you should lightly put it on the epoxy you have applied before. Be care of not to create even one bubble or ridges in it.


8. Wet the patch and put another carbon fiber piece on it.

What the goal we should to get to is to wet the part totally and get ready to put the next layer carbon fiber patch. First, any excess dust must be shaved off from the surface so it is significant to clean the repair area totally. After your cleaning the area then just put a larger carbon fiber patch on the wet surface of the last layer. Repeat the process as you own the another piece of carbon fiber patches.


9.wrap the frame with the shrink release tape

This step is little bit annoying. After paint it completely with epoxy you should be careful of not damage it by the wrong side of the tape. There is only one side with release agent. Finally don’t forget to heat it by your hair dryer or a true heat gun is even better. It would be fine to leave it more than 24 hours.


 10.Remove the tape

Finally peel the tape warping on the surface. We may find it a perfect repair with some excess resin. Just sand it a little bit and clean the carbon fiber frame with the lint-cloth.

Nowadays the frame would seem dirty and messy and you might want to repaint it by the chance. We have written an article about how to repaint the frame of your carbon fiber bike. Have a try to prepare yourself a brand-new frame. Have a nice day!


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