One of my winter projects is installation of a disc brake on my front wheel, which will mean changing out the fork, too. Many pre-built e-bikes are now coming with disc brakes. Anyone planning on installing a powerful motor that can propel them to 30 MPH or faster really needs disc brakes. You can retrofit the front brake on most bikes with V brakes if you change out the fork. However, it's almost impossible to retrofit rear V brakes and most bicycle manufacturers discourage attempts to retrofit rear V brakes with disc brakes.