Just received my new Shimano SLX pre-bled brake set but putting them on the bike there's way too much cable both front and rear.

Is there a way in which I can shorten the cables without losing most of the fluid in the system already?

Also which end is best to cut and what's best to cut the cable with I have cutters for gear outers and a stanley knife?

First of all, make sure you have a new olive and insert. Undo the hose to be shortened at the brake lever, cut with a very sharp knife, push new olive onto hose, insert new insert, screw back into brake lever.

Thanks Simon, worked like a charm 😀

Splendid.