Complex sentence: A launch loop would be held up at this altitude by momentum of the belt as it circulates around the structure, in effect it transfers the weight of the structure onto a pair of magnetic bearings, one at each end, which support it.
Split into simpler sentences: A launch loop would be held up at this altitude by momentum of the belt as it circulates around the structure. This circulation, in effect, transfers the weight of the structure onto a pair of magnetic bearings, one at each end, which support it.