There is no best length... whatever suits you and whatever you prefer... everyone's different..
The rule of thumb when buying bars is that they are as wide or slightly wider than your shoulders...
And I really don't understand why people cut down bars...??
Just buy the right fuppin' size in the first place..!!
don't you ever read the magazines like your supposed to ? Heimlich Noodles of Team Spanky in MTBwipeyourarsewiththismag did a feature last month about cutting your bars down, if your left handed he recommended cutting more off the right hand side to counter the devilish weakness being left handed can cause you on the local trails..c'mon Gerry, get current will you !!
Cheers for the input. I'm using the bike for xc racing only so I don't mind how long they could be. I'm not sure how ling the ones I have on the bike are so I'll check when I get home but I want to change them as the rise is to high on them. Moving the grips in sounds like a good idea. I thought that most bars come long so the option is there to cut them if you want?