Theres alot of missconception around carbon repairs and its no surprise that safety is a big concern when youre flying down a hill at 90kph in a 60zone on a tringlular piece of carbon.

Colourfuel conducted over 100 carbon repairs in 2022 alone. So we asked our carbon guy some questions to find out more about carbon frame repairs.

What’s your background?

I have been in the cycling industry since 2001 with carbon repairs starting in 2006. This has given me the opportunity to see how the carbon fibre technology has changed from the very first carbon bike frames and components all the way through to what we see today.

In 2012 I made a move over to the defence sector working with composite ballistic armour. Since then I have worked designing, engineering and manufacturing various forms of composite ballistic armour systems. This has given me an incredibly advanced knowledge of the failure mechanisms of composite materials.

I also have been known to produce custom sporting equipment using carbon fibre such as time trial handlebar, frames, shoes along with support devices.

Gloss finish on the modified metrons.
An example of hidden damage found during the painting process. (From a failed factory glue joint)

What can be repaired?

Technically speaking, all carbon based cycling equipment can be repaired, it just comes down to a matter of cost. Typically, frames, one piece wheels like disc wheels, three, four and five spokes wheels along wheels with bonded carbon spokes are all worthwhile due to their high replacement cost. Handlebars and forks are on a case by case basis and carbon rims are rarely worth the effort given the ready access and low to OEM rims out of Asia for replacement. Fork steerers are quite easy to extend and we have also modified handlebars on occasions.

Are carbon repairs safe?

When repaired by someone with a high degree of knowledge performs the repair, I would argue that the repaired area would have a higher degree of workmanship than what comes out of the factory. Most frame these days are made by a handful of factories in either China or Taiwan, mass produced by relatively low skilled labour. Most production frames contain a certain number of manufacturing defects from voids in the laminates to resin heavy pockets. That’s not to say that these frame and components are unsafe, you rarely see catastrophic failures out in the real world, just a reflection on the manufacturing environment.

With my repairs, I use higher quality materials than is typical with 5500Mpa tensile strength carbon fibres along with graphene fortified resins. Aerospace rated adhesives are also standard. This results in a stronger than factory repair.

An example of a wet layup.

What tools do you use?

Pretty standard toolkit for the composite industry, ultrasound probes, acoustic testing, inspection cameras along with the historical knowledge of the various manufacturing methodologies used for frames to know how secondary damage can occur from a large impact events.

OEM Raw carbon with custom gold leaf logos.

Will the repair affect resale?

A repair shouldn’t affect the value but people and the markets are irrational at times as we have all seen with the ridiculous prices we saw under the covid shortages. With a highly skilled repairer, the repair quality will typically exceed the quality of the rest of the frame. Quite often, many repairs I see are, in part, a result of a manufacturing defect. An acute impact event, such as a crash or transport damage, will occur over a manufacturing defect that contributes to the damage due to the weakness caused by said defect. You only need to turn to the Youtube engineers that cover the cycling industry to see examples of the manufacturing quality standards on carbon frames.

When you sell a frame it loses most of its value because the warranty services in most cases aren’t passed on to the buyer.

The truth is, your bike is worth exactly as much as someone is willing to pay for it. But a repair shouldn’t play any roll in that evaluation.

PrePreg vs liquid resin?

PrePreg is very useful for mass production and large laminates. When used in production environments, it is faster for production, allows for lower skilled labour to be used without sacrificing part quality since many of the variables such as resin content are controlled for within the material. It also limits the materials that are available, particularly within Australia, since we use such small volumes. Liquid resin systems can and do produce some of the highest quality parts within the cycling world. you can see examples of this with Thm (now Schmolke) parts, Time frames as well as at least some items coming from 3t. The process is much more intensive and requires a higher degree of skill but the result in second to none. Using liquid resins also opens up a much wider range of material options that just isn’t available with prepreg. in unskilled hands, however, you just end up with really expensive paper mache. I typically use liquid resin system as it allows for better quality materials like the higher grade carbon fibres. I’m a bit uncomfortable with being able to have the tight temperature controls needed for prepreg carbon in a spot repair application. The risk of having an incomplete cure of the repair or causing thermal damage to the factory area surrounding the repair is too high for my liking along with not knowing the chemistry of the resin used from factory. In this particular application, using a wet resin system gives a much more robust and predictable result.