The present invention provides optical fiber coating systems and coated optical fibers. According to one embodiment of the invention, a coated optical fiber includes an optical fiber having a core and a cladding; and a primary coating encapsulating the optical fiber, the primary coating having a Young's modulus of about 5 MPa or less, the primary coating being the cured reaction product of a primary curable composition having a gel time less than about 1.4 seconds at a UV intensity of 3.4 mW/cm.sup.2.