SEATTLE -- Dave Shaw didn't consider himself any kind of a pioneer in 1973 when he bought a helmet for bicycling.

"I just didn't think the soft-leather hairnets racers wore offered any head protection," said Shaw, 44, a former cycling road racer.

"A few rock-climbing helmets were available then, but they all were too hot, so I settled for a kayaking helmet. It was ventilated to let water out, offered very little crash-impact protection, but was much better than no helmet."

A fashion statement it wasn't. He looked downright goofy in it, but no worse than with the helmet he switched to a few years later. With its inverted-fishbowl appearance, Shaw looked like a space cadet.

The helmet had poor ventilation, so it was hot to wear in summer on even a moderately hilly ride. And at 18 ounces it was heavy enough to cause neck strain.

Still, he never left home on his bike without it, because it offered him his best hope of avoiding serious head injury in an accident.

Hard evidence of what Shaw and other cyclists knew through common sense did not surface until publication last year of results of a study by Seattle's Group Health Cooperative and Harborview Hospital.

The study said of the 1,000 cycling deaths in the nation each year, about 75 percent are the result of head injuries. It concluded that use of a helmet reduces a cyclist's risk of head injury by 85 percent.

The biggest push toward helmet use and improved design came four years earlier when the U.S. Cycling Federation announced that American National Standards Institute-approved helmets must be worn in all sanctioned races.

To meet standards, helmets, with head forms in them, must withstand a fall onto an anvil from a height of about two feet. Chin straps and buckles must pass a "jerk" test done at the same time.

Although the federal government does not require bicycle helmets to pass the safety tests required of motorcycle helmets, virtually all helmets sold in the United States now meet ANSI standards. Many also meet the slightly tougher Snell certification, said Randy Swart, director of the Bicycle Helmet Safety Institute in Washington, D.C.

Today's bicycle helmets come in three types:

No Shell: Some are foam-only; some come with a Lycra cover. The major advantage is the light weight, with some models weighing only eight or nine ounces.

Surprisingly, no-shell helmets often score among the highest in impact tests and many are certified by both Snell and ANSI. Most also come with Lycra or nylon covers to keep helmet pieces intact in a crash. And some, such as Pro-Tec's popular Mirage, also have molded-in reinforcement material.

Hard Shell: The hard shell not only helps prevent penetration by sharp objects, but a study, to be published soon by Wayne State (Mich.) University, will show that hard-shell helmets are more likely to slide on impact with pavement at some crash angles, rather than "grabbing" the pavement and causing neck or spinal injury.

The major disadvantage of the hard shell is weight; some weigh more than a pound.

Thin Shell: On the market less than a year, the thin shell is the latest product of helmet evolution. It combines light weight with penetration protection. And it may be less likely than the no-shells to hang up on pavement in a skidding crash.

There are few, if any, disadvantages to the thin shell.

The choice of which helmet to buy is, obviously, up to the individual. Helmets meeting most important criteria, such as certification, weight and penetration resistance, usually cost $30 to $90. A more expensive helmet is not necessarily safer or more comfortable. "Proper fit and ANSI or Snell certification are the most important considerations," Swart said.