I LOVE SSing. 29er is the way to go. Once you build up that momentum it is so much easier to crank down on the pedals while you are standing up on a 29er than a 26er and keep it rolling.

SSing works the heck out of your core and shoulders - it is a whole body thing. It makes your legs super strong climbing and makes you efficient spinning your brains out on the flats.

SSing may wreck your knees if you SS everyday - mix it up with gears some days for a bueno time.

I have a Voodoo Zaka which is 29er and can be set up as a SS or a geared bike. I also have a SS FS bike, a Lenz Milk Money, which is a really, really fun rig to play around on.

Next question if you get into SSing is gearing