i run the stock 140mm pike up front on my 29er stumpy evo and its fine. i dont see a need for any more suspension up front. I've taken my stumpy on trails that have eaten DH bikes and I've done "DH" races on it while my DH bike was down for maintenance and while its not as fast as a DH bike, it still handles the rough fine. you can feel the back flex when you get into super rough stuff and you'll wish you had more rear travel much before you wish you had front travel(although it still takes it like a champ). don't worry about it