Well...I have 21" front wheel and I don't trust the rim to hold a tubeless tyre. It doesn't have the extra rim bead (like a shoulder) to retain the tyre in case it deflates. So for me the 5mm UHD tube (Continental) does an excellent job. No more mini-spikes (from plants) that used to pierce all the way through the standard tube.
Later edit: Damn, a long and thin nail in my front tire (the one with UHD tube) from my last offroad trip. After 5 days the tire was still holding some pressure, just like a tubeless would. Not bad....
cristi-mic screwed with this post 04-18-2013 at 01:24 PM