My plan is to create some carbon fiber sleeve around the dent, just to make it a bit stronger. Is it a reasonable solution?
UPD: Impact occured around a year ago. I rode about 100 km on this frame from the time of impact.
UPD: I ride my bike mainly on asphalt roads but also on country roads with some sand, dirt, bumps, cracks etc.
UPD: It happened when I secured my bike on top of my car with Thule ProRide 598 car rack. And then I successfully hit my bike into the cieling of an underground parking lot. So the arm of a Thule rack was grabbing down tube around the bottle holder. It bent the bottleholder and and forced it into the down tube. So you can see those two bent marks - it is where the alluminium frame of bottle holder impacted the bike tube. I have two exact bottle holders and the second one you can see on the photo. The main impact occured to the front wheel which hit the parking roof. So there were two main points of contact: Wheel iself and Thule arm. Wheel bent a bit and was repaired by a mechanic on a machine. Actually right after the accident I rode 10 km home and didn't notice any damage at all. I noticed damage to the wheel only when decided to change front wheel dynamo hub to other model. Thule arm pushed bottle holder into frame and
UPD: My insurance doesn't cover this case.
Conclusion for now 26.05.2023: I will try to create a carbon fiber sleeve. I will fill the dent with some Bondo putty, just to recreate the frame shape. Than I will use solder acid to prepare aluminium for a glue contact. Than I will apply glass fiber as a first layer to prevent aluminium from galvanic oxidation with carbon. Than I will apply around 3 mm of carbon fiber and cure it with a heating lamp.
As far as we investigated that down tube is a subject not only of tensional but also of torsion forces (that is why this model has sort of rectangular shape I guess) I think it will be a reasonable solution to create some kind of support in the place of a dent. It also should prevent any kind of aluminium wear or corrosion in that area.
I will try to post updates on my progress here or in other post.
Also, I will try to do this because I have time and effort. In other case I would just let it be and ride normally with periodical "health check ups" of the down tube.