regarding tubeless for mountain biking...it's the way to go. the cheapest and best way (IMHO) to convert is using the STAN's System. Go to notubes.com for info. The key in going tubeless is the sealant used inside the tire. Stans allows you to use your current wheelset and tires for go tubeless. You can save quite a bit of weight going this route since most tubeless wheels are heavier than standard wheels. Also, tubeless specific tires are also heavier than standard clinchers. I've been using this system for over 4 years and have never flatted (pulled many thorns from my tires though). I even use Stan's sealant in my tubular tires on my road bike.