Preparation Makes for Easy Riding : Extended bike trips are more enjoyable when cyclists start training six months before leaving home.

Toting water bottles and high-energy snacks, some 35,000 people will pedal across the nation’s highways and back roads this year, taking part in pleasure bike tours of a week or longer. Some riders will return home feeling refreshed and physically fit. Others will come back tempted to kick their bikes . . . if only they had the energy.

What explains the gap between the two reactions? Training and planning versus none.

Unlike packing a suitcase, getting in shape for a bike tour cannot be put off until the night before the trip. But neither does it take incomparable fortitude or every spare moment of leisure time to prepare.

First-timers in reasonably good shape should probably begin training six months before a bike tour, advises Philip Walker, a fitness management consultant at the Cooper Clinic in Dallas. Sedentary first-timers should follow the same six-month training schedule but only after first getting clearance from their doctors.

The best training for cycling is cycling, Walker and other experts agree. But cross-training--running, walking or swimming workouts interspersed with biking--can’t hurt either and can boost endurance, most say.

Begin slowly, advised Douglas Torosian, acting director of Pedal for Power, a program of the Bicyclists’ Educational and Legal Foundation of the League of American Wheelmen, a national organization of cyclists. First-timers without much experience could begin with a 15-mile ride, three or four days a week. Increase mileage gradually, perhaps by 10% or 20% a week, Torosian said, thinking in terms of hours on the bike, rather than miles, which can seem threatening to beginners.

Once in shape, cyclists should put in at least one long training day before the tour, logging the number of miles they will put in daily on the road. Close to the tour departure date, cyclists should ride seven days a week, if that’s the schedule on tour, Walker said. Get in the habit, too, of doing leg stretching exercises before getting on the bike, Walker said.

Find out well in advance of the trip what kind of terrain the tour will cover. If your tour includes hills but your training doesn’t, your quadriceps (muscles on the front of the thighs) will probably ache badly, said sports medicine specialist Dr. Tony Daly, a staff physician at Daniel Freeman Marina Hospital in Marina del Rey and team doctor for basketball’s Los Angeles Clippers.

Even if your usual bike route is flat, it’s easy to get in shape for the hills. Concentrate on building endurance during your outside cycling sessions, Walker advises, and do your “hill work” at the health club by programming in “hills” on a stationary exercise bike.

Of course, people who stay physically fit year-round have the easiest time getting in condition for a bike tour. But they, too, should boost activity as tour time approaches. Dr. Phil Yalowitz, 54, a urologist at Cedars-Sinai Medical Center, runs and cycles throughout the year. His typical weekly routine includes 30 to 50 miles running and 15 miles cycling. But he changes his routine before the two 300- to 500-mile bike tours he does each year. “About three or four weeks before the tour, I lengthen my weekly bike ride to 30 or 50 miles, sometimes even 70. I do lots of hills.”

Lest that routine intimidate novices, Torosian offers this reassuring advice: “Mileage does not matter as much as getting on the bike consistently.” And since bike tours are not designed as races but as pleasurable jaunts, endurance counts much more than speed.

Don’t train hard right up to the point of departure, experts advise. Cut down on mileage (Walker recommends trimming it in half) about two weeks before the tour, but keep riding.

Even the best training routine can’t compensate for bad equipment. If you’re buying a bike for the tour, most any kind is accepted, tour operators say. Best bets are touring or racing bikes, according to Torosian. And make sure the bike is the proper size. Cycling on a bicycle that’s too big or too small sets up cyclists for knee and other problems.

Be sure the bike seat is comfortable. An ill-fitting seat can lead to rashes, sores, boils, numbness, even impotency, some experts say. When shopping, tell the bike shop operator details about your tour, such as daily mileage and terrain. Such information can help narrow down the best choice from many styles.

Wearing good cycling shorts with a soft liner to cushion the impact can help prevent chafing. And wearing clean shorts will prevent bacteria buildup and thus minimize the risk of infections and sores.

Besides a good, comfortable bike, a helmet is recommended, as is a water bottle “cage” to hold the bottle to the bike. Some experts recommend a good cross-training shoe; others swear by cycling shoes.

Try out all the equipment for at least a month before your bike tour, Daly recommends. That will allow enough time to exchange or adjust anything that’s not comfortable.

Should you be taking an organized bike tour that is equipped with a “sag” (support-and-gear) van filled with tools for technical assistance and medical supplies, carrying a bike-repair kit and first-aid provisions isn’t necessary. But if your tour is less luxurious or self-guided, experts advise taking along a compact first-aid kit designed for automobile use or to make your own. Daly recommends packing sun block, lip balm, bandages and antibacterial spray. Don’t skimp on the latter two, he said, since most injuries from cycling are the result of falls.

And be prepared for temperature extremes. One simple, inexpensive form of protection can be a piece of brown grocery-bag paper big enough to cover your chest. Stow it in your gear and when it turns unbearably cold and windy, “put the brown paper under your cycling jersey,” Walker said. “It will keep out the chill.”

Take along snacks high in carbohydrates and low in sugar. “Always check the fat content,” Torosian says. “You don’t want to eat anything that is 30% or 40% fat.” On most cyclists’ “A” list are fresh fruits and sports bars. Yalowitz swears by fig cookies (fat-free is best). But Walker is less of a “no-sugar” die-hard. There’s no harm in sneaking in an occasional candy bar, as long as most of the other snacks are high carbohydrate, he said.

Drink plenty of fluids--plain water or sports drinks--to prevent dehydration. Sports drinks such as Gatorade should be diluted unless they are the new “lite” formulas. The regular versions are too concentrated, Walker said.

If water is your choice, don’t drink it ice-cold, Torosian tells riders, and it’s always best to observe the motto, “Drink before you’re thirsty.” Torosian suggests sipping from the bike bottle every 10 minutes.

Even the fittest cyclist should consider unwinding at day’s end to minimize sore muscles later, Daly said. “If it has been an usually hard cycling day, it’s a good idea to take a light warm-down ride. Or if a stationary bike is available, set it at no tension and ride a few minutes.”