BODY : NOT WANTING TO HIT THE BOTTLE, ATHLETES DRINK UP WATER PACK.

Byline: Scot Meyer The New York Times

Roger Fawcett began to rethink the sports water bottle after a friend rode in a 100-mile bike ride in Wichita Falls, Texas. The temperature reached 106 degrees that day, and water bottles did not carry enough water or keep it cool. Reaching for a water bottle while pedaling among other riders sometimes meant veering into another cyclist. Fawcett thought there had to be a better way.

``We sewed a sock on a cycling jersey and, just for fun, put an enema bag in the sock,'' said Fawcett, who was an amateur inventor at the time. ``We put it in upside down and ran the tube over, and that was the beginning.''

He's come a long way since then. He is now the president of Fastrak, maker of the Camelbak line of water packs, which are catching on among recreational athletes.

They are simple in design: a soft plastic bladder filled with water and ice fits inside an insulated nylon carrier, which is strapped on the back or around the waist. A long plastic tube is clipped to a convenient spot - say, the shoulder - so that the wearer can grab it and sip without fumbling for a bottle or taking his eyes off the road.

Adjustable straps keep the water packs comfortably in place. And there's no sloshing; the bladder contracts as the water is drawn out.

Water packs cost $20 to $75, depending on capacity and the number of features. A 32-ounce belt pack by the IAO Corp. is $20; a 90-ounce backpack style by Camelbak is $66. Some have valves that allow you to bite the end of the tube to start the water flowing, instead of flipping a switch. IAO's Liquipak has a bladder made from a plastic laminate that can be frozen.

The products have been adopted by hikers and skiers because they encourage frequent sipping. Experts in sports medicine say 6 to 8 ounces of water should be drunk every 15 minutes during vigorous exercise to avoid dehydration.

Camelbaks were a tough sell at first. ``I kept hearing that the thing was geeky,'' Fawcett said. He then gave them a sportier design.

Laurie Brandt, a professional mountain-bike rider from Louisville, Colo., said that at first she thought carrying water on her back would be awkward. But she now uses a water pack when she trains and wears one during some races.

``The thing about riding a mountain bike is that a lot of times you can't take your hands off the bars for very long,'' she said. ``So with a water bottle you tend not to drink enough.''