Where have the 10-speeds gone? Bike fad fades

America's bike boom has had a blowout.

Despite some media predictions in the early '70s that the bike would help wheel America toward energy independence, the car is still taking most Americans almost everywhere they go.

Observers at the time said the bike would be a boon to commuters, who could save gas and stay fit by pedaling to work. But today only 0.6 percent of the nation's work force is traveling to work on bikes. Overall, industry analysts expect bike production to fall 25 percent this year.

This contrasts with cycling trends of the '70s. For example, in 1972, more bikes were bought than cars. Between 1972 and 1975, an estimated 45 million people bought lightweight 10-speed bikes, according to experts.

Yet as the bikes wore out or were stolen, most cyclists found the cost of a replacement just out of reach. Today, one of the new, ''competitively priced'' Japanese models can cost twice as much as a new $100 Peugeot (one of the more popular bikes during the decade) did 10 years ago. Repair costs are also high - in some cases more than $100 for a complete overhaul, and can end up higher than a bike's original price.

Bike shops around the country are feeling the pinch. Mike Krippendorf, manager of the Turin Bicycle Shop in Evanston, Ill., reports that the bike business in his area is ''exceptionally quiet.'' During the 1971-73 cycling surge, he says, his store ''would sell and deliver 26 bikes a day.'' Now in the busiest season of the year, he sells only seven to nine bikes a day. ''Like any other industry,'' he says, ''this one is experiencing a bit of a slowdown.''

Terry Jo Snyder, a spokeswoman for the Schwinn Bicycle Company, agrees. While Schwinn itself is trying to recover from a six-month strike last year, Snyder says, ''the whole industry has felt the current recession.''

Clint Page, manager for Ace Wheel Works in Cambridge, Mass., predicts for this year a 5 to 8 percent slump, reducing sales nationwide to almost half of the 1973 high of 15.2 million bikes sold. ''A lot of people,'' he says, ''are choosing to use their old bikes.''

Oddly enough, sales of high-priced touring and racing bikes is cranking along at full speed. Less than a year after setting up shop in his Hinesburg, Vt., basement, bike frame builder Michael Petrie has put more than 20 of his $400 -plus hand-built frames on the road, and is booked into the fall with orders.

Petrie claims that ''as soon as you get hooked on cycling, you'll spend whatever you can on a high-end product.''

But most bike manufacturers and retailers concede that the big top-of-the-line bicycle dollars are coming only from those who have the extra money to spend. Schwinn's Snyder says that most of her company's customers are college educated with combined incomes of more than $20,000. Mike Krippendorf sees mostly young professionals in his shop buying bikes costing over $400.

Optimism still exists, though, among those such as Katie Moran of the National Bicycle Federation, which coordinates state and local bicycle programs. Moran is encouraged by what she calls the ''subdued increase'' of cycling in the United States, noting that New York still has three people working full-time on bike projects after the city dismantled its bikeways. She also says Denver officials have noted a 30 percent increase in bicycle commuters each year, and that 15 percent of the Madison, Wis., work force commutes by bike.

''Biking at the local level is going well,'' she says, with more and more safety-conscious cyclers wearing helmets, and a large number of riders with modest incomes using one- and three-speeds.

But she hesitates to call cycling's slow but steady growth anything like a boom, ''because with every boom, there's a bust.''