[SiliconKnight]

We used them last year. They are pretty grippy, and the biggest advantage is because the wheels deform to take the weight, it is a bit more forgiving if you aren't lined up perfectly in the vertical direction, all the wheels will still contact, and you'll get a decent contact patch.

If you are using the sprocket driven hubs, I'd recommend that you put about 2-4 oz of slime (tm) into the inner tube before you inflate them. I've been using slime in my mountain bike(s) for the past 10 years, and can count on 1 hand the amount of times I've had a flat tyre. Once the hubs go on it's dang near impossible to pump the tubes back up, so tire sealant in the tubes to guard against slow leaks (which *will* happen) is a worthy investment. Go to your friendly local bike store for slime, it's a green goop that they sell in a tall plastic bottle.

Happy chips,

-=- Terence