You can use MagicCut to Split your files visually.You can adjust file size from 1G to one byte by just simply click and drag.
Main features:
1.Visually simulate file split plan.
2.Visually adjust and merge file slices.
3.Support five kind of split mode,Wizard mode and Classic mode.
4.Accept files from windows explorer by Drag and drop.
5.Split files from windows explorer popup menu.
6.No need to install any program when merge files.