I am super impressed by your repair. How did you get the two parts to bond together, there must be overlap between the bit you replaced and the frame, right? And how did you get the right shape out of the bit you replaced?
I got the stuff from a local composite shop. I used dry carbon cloth sheets and 2 component ready-to-mix epoxy. I used multidirectional rather than UD sheets. Now dry carbon cloth is rather fragile to handle because you can easily move and shift the fibres in the matrix and applying the epoxy can be a rather messy job. BUT the upside is that it can easily be manipulated into any shape you want.
You need to liberally sand off the affected area to expose any cracks. I’ve read various guides as to how to do this and depending on how high stressed the area is you should reinforce at least three to five times the length of the crack.
I made sure to use material with the same properties as the T700 that the frame is made out of. I checked the spec sheet and the fibres I used have a slightly lower tensile strength but the same e-module/elasticity which means they should flex the same way under load than the original material.
I applied one layer on the inside and two layers on the outside. Now the hard part is compressing the whole thing for it to cure. On the inside, I actually used the seatpost wedge itself wrapped in thin plastic foil to compress the area. On the outside I wrapped everything tightly in plastic and heat it up slightly for it to shrink.
Once it’s completely dry you can peel the foil off.
The inside was rather messy and it took A LOT of sanding and trying until the seatpost and wedge fit correctly. It was actually too tight after the repair. Now the wedge sits flush and fits better than before arguably. On the outside the surface was pretty good to begin with.
The manufacturer recommends that the repaired area be tempered at about 50 degrees Celsius for the epoxy to cure even harder. Now that I could not do. But it still hardened reasonably well.
The final step is smoothing out the edges of the repaired area to create a smooth surface to paint over without any visible overlap. That’s what I haven’t done yet.
I’ve now ridden the frame around 800k with the repair and I’m confident it’ll hold up. Just don’t know yet how exactly I’ll paint it because I won’t be able to match the color. I’ll probably go just with black.
I thought about manipulating the fibres to form the two holes in order for the fibres to not be interrupted and increase strength. I tried it but it shifts the whole matrix around and you don’t want that. So I’m the end I just covered the in- and outside completely and drilled it afterwards.
The whole repair cost me 20EUR / about 20USD. I got a quote from a local composite expert before I tried it and he would have charged me 350 including the paintjob. He would probably have done it a bit cleaner than I was able to. But I’m glad I tried it.
Sorry for the lengthy post!
