We're going from yesterdays post that had to do with a lack of flex in handlebars to an anti-flex post today in regards to 29"er frames. Flex: It's good in some places, other places- not so good.
Take front and rear triangles of a lot of 29"ers out there, particularly front triangles. They are too flexy. Too much twist, bend, and tweakage in all the wrong directions. Some frames have this dialed out, but they are the minority, and of those some are real tanks. A leight weight, non-flexy 29"er frameset is hard to come by.
Word is that the Fisher has really dialed in this area for '08. If so, it would be one of the only line ups of 29"ers that was rigid torsionally top to bottom. I rode a Paragon '08 model at the Big Wheeled Ballyhoo in June, and if that ride was any indication, I'd say this was truth.
What am I talking about here? Well, if you have a twenty nine incher handy, hop on, grab the grips, and alternately push and pull on the bars as if you were grunting up a climb. (Only you aren't, you're just straddling the bike) You'll likely notice that the ends of the handle bar are going up and down and that your front end is flexing in a strange way. It's those long top and down tubes that are to blame. More length due to the bigger wheels means more chance for twisty flex. The shorter head tubes don't help much either. This all translates to some strange handling characteristics out on the trail. Stuff we don't need.
Hopefully 29"er geometry and tubing technology will be getting more and more dialed in now with the popularity of the big wheels and this flexiness will become a thing of the past. Quite honestly, it's one of the major things that keeps a lot of high performance racers and enthusiasts off big wheels. With the newer crop of Fishers and others that are following suit, like Salsa and Lenz Sport, this problem should start to fade away as people gravitate towards the more solid handling and feel of these bikes.