cunn1n9 wrote:I had my r5ca top tube repair after I ran up the back of a car and had it crack. Cannot tell at all now good as before (albeit 20g heavier) and the repairer told be it is now stronger too.
I would be concerned about a 20g increase in weight and the statement of it now being stronger than before.
20g is a LOT of carbon, the entire top tube of a R4ca would weigh about 60g, to add another 3rd of that again in material would change the stiffness and thus how the loads flow through the structure. The "repair" may be stronger, however the overall frame is not stronger as the load paths have changed. Put a big link into a small chain and it still is as strong as a small chain. For a top tube I would expect a weight difference of no more than 5g and typically about 1-3g including paint.
Also some things aren't suitable for repair, we see cases where a top tube has a small visible crack where the handlebar has swung around and impacted it. When we do the Ultrasound scan of the area, we find the majority of the top tube has delaminated and the frame is scrapped.
There are lots of people springing up offering carbon repairs, as it is easy to wrap a bit of carbon around something and give it a nice paint job. However a real repair is a bit different to that and takes into account the entire structure not just the cosmetic finish. When descending a mtn at high speed do you think about the paint finish looking nice or the structure being sound?
Stay safe out there people, a cheap and nasty repair is false economy.