Hey Randall,
Your idea is a good one, but it's
not really a "tubeless" setup. It is simply a DIY
slime tube (or more like a 'sealant' tube, as we've
mostly all gone to using sealant like Stan's instead
of that green slime), something many of us have been
doing for a long time. In the method you describe,
you're taking off the little cylindrical valve nut
(sometimes requiring filing the valve stem plunger to
get off), and filling the tube with sealant while
keeping your thumb on the back of the tube to keep the
valve stem core from dropping into the tube.
Like I said, it's a good idea, but
not the same as a true tubeless setup. There various
justifications to just go without the tube. The main
thing is the mechanics of the "ride" of the tire, or
how the sidewall deforms under pressure and how it
affects the tire's contact to the road. This is
somewhat different from what the tire does with a tube
in it. You can still pinch-flat a sealant tube, and
it likely will NOT seal because the lacerations in a
pinch flat are just too big to seal.
Also, the tubeless tire setup
actually seals much more quickly than a tube with
sealant -- much more quickly, in most cases.
The investment for the tubeless
setups is not that much, and in the end pays for
itself with the fact that you don't have to deal with
tubes nearly as much as before. If you're like me,
you probably have a bunch of old tubes with a hole or
two sitting around collecting dust and dry rotting. I
used to be able to give them to the junior kids around
here and teach them how to patch them, then they just
got to keep them. Now, not that many kids get into
cycling, so I've collected more than I want to admit.
Anyway, tubeless eliminates a lot of this.
So, to get to my point, you can buy
that same tape that Stan's sells for much cheaper --
3M makes that 1/2" clear weather seal adhesive tape,
which is essentially the same thing. There are lots
of 3M adhesive tapes that work OK for the purpose, and
if you REALLY want it to seal, just make a couple of
quick passes over it with a heat gun (don't burn
through it, though).
You still gotta buy the tubeless
valve stems, though. That is not a big expense. You
also have to use a pretty sturdy folding clincher. I
don't think a tire with a steel bead would work as
tubeless (who uses those anyway?).
The main thing that makes this a
"specialty" product, however, is the need to have an
air compressor. You just can't get that air surge
that you need from a hand pump alone. You gotta have
an air compressor and a presta to schrader valve
adapter.