Maybe it changes height to last longer or something... Eh. I can actually see the 4D bottom idea working for Defense. Stamina isn't easy to improve given what it has (though I wouldn't be surprised if, now that they have room to fit it in, we see a proper MFB Bearing Core), but with defense, there's the possibility of a 4D Bottom with enough grip at the start of the battle to weather the early onslaught from attack types, and then switch into a stamina mode to outlast certain balance types. Or something, I'm just guessing.
And I wouldn't entirely write Big Bang off yet, it has got decent enough smash, and it's width and shape, plus the PCB Ring or whatever, do leave room for versatility. Maybe we'll get a new piece that'll have great chemistry with it. That said, I'm far more excited about LDD.
Nano, that happens to me when the track is cracked, and it comes loose after a few hits.
I' concerned vulcan is breaking my tracks. The wheel has unbelievable smash, but I'm concerned between that and the grip to the floor, the track is bearing the stresses, and that's why my CH120 (and 85) are starting to crack a little. I've been very, very careful with my new CH120's, but after removing it from Vulcan after some testing against Basalt, it started to feel "tight" when changing heights. Low and behold, it's starting to crack on one side...