  We report peculiar vortex motion in clean Bi$_2$Sr$_2$CaCu$_2$O$_8$ single
crystals, which reveals nearly linear-$T$ resistivity tails extending to low
temperatures. The resistivity was found to satisfy the classical
Bardeen-Stephen model for free flux flow, which is otherwise hard to observe
under normal experimental conditions in high-$T_c$ cuprates. Moreover, in the
superclean regime, a universal temperature-independent value for the flux flow
resistivity was observed, $\rho_f = 1.4(B-B^*)$. We interpret this
carrier-relaxation {\it independent} behavior as being related to the
dissipation caused by the minigap states within the vortex core. The results
are in agreement with theoretical calculations (N. B. Kopnin and G. E. Volovik,
Phys. Rev. Lett. {\bf 79}, 1377 (1997)).
