Walk around the streets of Beijing these days and the sidewalks are thronged with yellow and orange bicycles. These are the weapons of choice in one of the strangest, most colorful battles in the technology world. Ofo, the company behind the yellow two-wheelers, just raised $450 million at a valuation of more than $1 billion. Orange-hued Mobike raised $300 million a month earlier. And they’re not the only two: Bluegogo and green-favoring Forever have also sprouted up over the past year to offer bicycle sharing amid the controlled chaos that is Chinese urban traffic.