The crankset is largely hidden behind the front wheel. As long as the stresses are spread out there is no concern or need for anything central. On my Brompton I have a triple crank that obviously sticks a bit more than standard but there had never been any problems in travel in either a soft bag or the tight B&W case that presumably puts more stress than a soft bag will in airline circumstances. I cannot comment on the brake caliper, without understanding details, except for an off the cuff that there is a need to choose one's battles.