I recently got a new FS XC bike. The bars are 800mm wide, which is about five times wider than the ones on my 2008 26" FS bike, which has a long stem.

I am not what you would call an Enduro Bro.

Although I have owned mountain bikes since about 1992, I don't really feel like a competent mountain biker.

My instinct is to saw off about 50 to 100mm from each side of the bar, because my wrists hurt, but I also am reluctant to change stuff that would degrade a new bike with "Down Country" modern geometry. (The bike is a Cervelo ZFS-5, which is essentially a Pon clone of the SC Blur, trail version.)

How do I determine how wide the bars "should" be. (The distance from the nose of my saddle to the outer hand position is the same now as that from my saddle nose to the hoods on my drop bar all-road bike, which is custom-fitted, which maybe suggests I should leave it alone.)