BIKES: Kit's cost may be reason it hasn't caught on in Alaska. The loud pop, coming as it... Tubeless tires deflate fear of fal

First, there is the bang of the tire. Then comes the whomp of a body hitting pavement or the ground. And finally there is some pathetic human moaning or cursing.

Cost may be why, said Jon Kunesh, manager at Paramount Cycles. You can buy more than a dozen bike tubes for the $80 it costs for the Stan's kit to convert two wheels to tubeless.

Riders in thorn country have discovered Stan's sealant will quickly find and plug holes made by thorns, no matter if the thorn punctures the tire and pulls out or stays stuck in the rubber.

On Stan's Web site -- www.notubes.com -- the company illustrates the effectiveness of its sealant by showing a still fully inflated tire with nails, screws, thorns, even ice picks and screwdrivers jutting from it.

A problem with tire leaks in 2004 first attracted my attention to Stan's. I was riding frequently on a rough road littered with sharp, broken rocks.

None of these flats were catastrophic, but they were aggravating. Often the leaks were small enough that the tire would look fine on arrival home but would be flat the next morning.

After a couple of weeks of pulling off tires, stripping out tubes, patching them and putting them back, I decided there had to be a better way. Enter Stan's.

An after-market product designed to make almost any bicycle wheel tubeless -- just like automobile tires -- it consists of a rim strip and some liquid sealant. The rim strip, which keeps air from leaking out of the spoke holes in the rims, can in many cases be used by itself with a tubeless tire to make a tubeless wheel.

Unfortunately, most tubeless tires are significantly heavier than their tubed counterparts, and tire weight is the most burdensome weight you can put on a bike, particularly one ridden uphill regularly.

Thus I've pretty much given up on tubeless tires and simply use a few tablespoons of Stan's Sealant in a regular tire to make it tubeless. There are detailed instructions on the Stan's Web site explaining how to do this.

On my commuter mountain bike, which goes both on- and off-road between downtown and the Hillside, I've used this system to convert some ultralight Kenda Klimax Lite tires to tubeless.

Pumped up to 70 or 80 pounds, they're about as hard and fast as anyone could hope for in a mountain bike tire. And they're light enough that they help drop the weight of my old Specialized Stumpjumper hardtail below that of many of the road bikes parked next to it in the bike rack.

It makes a mountain bike commuter almost as fast as a road biker but with an additional degree of safety. I haven't had a catastrophic tire failure since converting to Stan's, and I've got the road-rash-free body to prove it.

Both Paramount and The Bicycle Shop in Anchorage have or can get Stan's kits. If you've got a serious rider on your Christmas list, you might even think about this as a gift.

It isn't pretty. It's a bit of a pain to install. And the sealant goop can be messy. But whatever the points on the downside, they are vastly outweighed by the points on the upside.

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