Superlight vs. Stumpjumer
Bishop,
When choosing a bicycle always remember that they're like blue jeans--they gotta fit. When your bike doesn't fit you properly, your weight isn't evenly distributed across your wheels (men usually wind up with too much weight on their front), and all the techno-trickery you buy can't make up for that imbalance. Any bike shop/employee worth their salt shouldn't even let you buy a bicycle without watching you ride it and evaluating how it fits you.
Here are a couple quick tips:
If the saddle is close to either end of its adjustment, all the up or all the down, the bike, or at least that size, is not for you.
Minor adjustements in the cockpit, different bars, different stem, etc., are fine. Huge adjustments are not. If they're needed, that's not the bike/size for you.
For the type of bike you are shopping for, you should not, I repeat, not, be able to put your feet on the ground while sitting on the saddle. If you can, the bike is too small for you.
At the bottom of your pedal stroke, you knee should be almost straight. Not entirely, but close.
Finally, most people buy bikes that are too small for them. I'd estimate about 80% of the bicycles I see are too small for the people riding them. Now matter how crazy it sounds, always, always test ride a size larger than you think you need. And take your time--get to know it before you decide it's too big.
I should mention that I'm speaking from experience here; I spent 12 years fitting mountain bikes in shops all over the northern rockies.
Here's a great website with a weath indispensable info.
http://www.mtbr.com/reviews/xc_full_suspension/product_123150.shtml
http://www.mtbr.com/reviews/xc_full_suspension/product_123231.shtml
Just in case I'm not allowed to post links (I'm a newbie to BARF), just google "mountain bike reviews" and click the first link that comes up. Then use the pull-downs for reviews of what you're shopping for.
Good luck to you and I hope to see you on a trail some day!
Greggar