I've been wanting to do this for a long time! I managed to chance across a pair of BST wheels which were sold as damaged - in the interest of science and asking a few questions of the seller relating to the damage I bought them for not much monies. As it happens, the rear wheel was actually good, it was only some laquer which had chipped off it following a chain jump but other than that it was all good. Bonus. The front was the one which was damaged. The initial premise was that the owner had smashed the wheel onto a kerb. The bike had managed to limp home but the tyre had retained pressure, and having had the tyre still on the wheel for over a week without pressure loss. On receiving the wheels, I set about photographing the damage. I wanted to see to what extent the damage had penetrated and also the feasibility of infiltration and re-moulding to effect a repair if the damage was not severe. As you may have gathered I have great faith in this material. The initial visual read shows us an area approximately 90 where there is noticeable cracking of the surface ply and resin matrix. A woodpecker test shows that the delamination extends around 100mm either side of the spoke. This isn't readily apparent as the extremities of the delamination the plies are intact save for some resin crack witnessing. Unfortunately what is also apparent is a buckling of the composite. On the inside face, the only catastrophic ply failure is on the bead, but not on the tyre seat - which is intact. However you can see either side of it the fibres have taken a massive impact load. I was impressed. I know how much abuse this material can take, and to boot, I know how much abuse these wheels can take. They are pre-preg decent aerospace structural composite (very different to bodywork pre-preg systems) construction and autoclave cured unlike dymag who wet-lay their wheels. It's safe to say that this load was in excess of 3g if not 4 and it still didn't penetrate the main body of the wheel. The initial impression was that perhaps this wasn't beyond saving. I could easily repair this sort of damage - and have done. So more closer inspection was due to see if there was anything I'd missed. Unfortunately I then noticed more damaged at the spoke. Ok, so now it's a different story. What first appeared as stressed lacquer was indeed distressed resin damage which means that we've seen some high energy loads pass this way. Without knowing the lay-up in this area I was cautious as to how to proceed next. As fate would have it, BST popped into work, and I had the opportunity to have a really long chat with them. I have to say great guys. Justifiably they were nervous about the spokes. So at this point, I cut out the hub, and handed it back to them and began the autopsy on the wheel. In cutting out the hub I was really pleasantly surprised. It was nicely laminated and well laminated. the material thickness was constant and the ply overlaps were nicely done. There wasn't any detritus in there, nor was there any sign of sacrificial bags or release films. Done right. Severe impact caused heavy delamination on the surface ply - christ you might think... The extent of damage was a nice clean split: This is good for many reasons, but the one you need to know is that there's a sacrificial ply in there. This is engineered to take the brunt of the force and intentionally fail before the rest of the wheel gets blasted. Testament to that is the fact that they still allowed the tyre to hold air. Chopping a section through this bit, we see where the brunt of the impact was and again, the laminate has done a good job of absorbing the worst of the energy from the strike. The spoke areas itself though was the bit that made my little heart jump for joy... apart from surface damage to some resin and lacquer there was no internal ply delamination I draw your attention to the stripe that you can see in a different shade that permeates the stratified plies. This is unidirectional material, the structural heartwood if you like of the layup. Summary The wheel itself despite suffering massive impact was at its most critical structural point still capable of and had survived, and that's great news for anyone thinking or worrying about whether BST rims are a good idea or not. I'd have happily gone ahead and repaired that rim, and albeit it would have been a very long and involved repair, I'd have still been happy to put my faith in it. Would I say to you guys go and do it? - of course not. But i'd definitely rate these BST hoops over a dymag in the event of a running out of talent situation. Dymag take a slightly different approach where they have put a weakened bead structure in. It's designed to collapse on taking damage with the intention of causing intentional deflation of the tyre, whereas BST have adopted the visual failsafe approach in respect to ensuring that damage to the rim is visibly apparent so forcing you the owner to seek advice. They both achieve the same end, but I like this approach better as there's no fudging that the wheel has taken damage. They're not only TUV rated but also certified for Japan, so meet the same stringent requirements as the OEM wheels.