Mountain Biking - Riser bars?

I have a Stumpjumper and i'd like to raise the height of the bars a bit for several reasons. One to provide clearance between the shifters and top tube when bar is spun during a crash, and two, to provide a little easier riding position for my lower back.

My question is: What is the best way to do this ..... a riser bar, or change the stem angle? I appreciate any feedback!

Thanks

Both solutions will work, risers are nice.
A very upright stem would look kinda funny on a mtb.

maybe get a 1.5" rise with a slightly more upright stem?

I just got a riser on my Stumpjumper. It is much better now. It is a little weird at first. It was more comfortable but i felt like i was riding a different bike so it took a little to get used to. I recomend a riser bar maybe 1.5" like seely said.

I did both in my situation

Thanks for the replies. I think my LBS has ordered up a Specialized riser bar for me to try. Did all of you stick with the thicker 31.8mm bars or switch back to the thinner 25.4mm? The only thing I don't like about the 31.8's is it makes it harder to mount a headlight towards the center of the bar???

Delta makes a nice stem extension for threadless 1 1/8" stems that works also. It simply bolts onto the steer tube where the stem goes on, then you bolt the stem onto the top of the extension. It will give you about 2-3 inches of rise. I corrected my mistake, it was made by delta not ahead.

Thanks for the replies. I think my LBS has ordered up a Specialized riser bar for me to try. Did all of you stick with the thicker 31.8mm bars or switch back to the thinner 25.4mm? The only thing I don't like about the 31.8's is it makes it harder to mount a headlight towards the center of the bar???
I use 25.4 on mine