Your absolute max for that controller will be what is printed on the caps. If it says 63v, then you can run "48v", up to 63v fully charged. Most will stop with 14s, which charges to about 58v.
Some 36v controllers will only have 50v caps, which means you could push it only as far as 12s, which will still be slightly over 50v fully charged. But you could undercharge, or risk 5 min over 50v as you ride the first mile.