IN MID-JULY this year, I called my unsainted 79-year-old mother in Albany, N.Y., and said: "Don't worry if you don't hear from us for a while -- we are going on vacation."

My mother said: "Where are you going this year?"

I said: "Iowa."

She said: "Iowa! What's in Iowa?"

I said: "We are going to bicycle across Iowa."

She said: "Oh dear. Why don't you go to the beach?"

Four days later we -- my wife Tod and 13-year-old daughter Becky -- were in Grinnell, Iowa, the guests of Al and Dorothy Pinder, who had first suggested that we might want to join RAGBRAI (The Des Moines Register and Tribune's Annual Great Bicycle Ride Across Iowa). That night at dinner, the Pinders invited a 103-year-old man who they claimed had done the last four RAGBRAIs. He talked and we (casual bicyclists at best) listened attentively and in awe to everthing he said. What a challenge!

After that night, we never saw the 103-year-old man again.

RAGBRAI was conceived seven years ago by Register and Tribune writers John Karras and Don Kaul. The number of participants has grown from 125 to between 4,000 and 5,000 this year (some persons join for a day or two to swell a swollen horde). It takes place every late July and early August to capitalize on the dry season (it thundered and lightninged and deluged three times) and lasts for seven days, rolling along Iowa's back roads from the Missouri River in the west to the Mississippi River in the east.

The rout is west to east to take advantage of the prevailing winds. But we discovered that no matter in which direction we rode, we had headwinds. Indeed, I was so frustrated on Thursday (the 100-mile day) thatI completed part of the ride backwards so I could experience a tailwind before leaving Iowa.

This summer's ride was the longest -- 480 official miles but closer to 500 through a miscalculation.

Each day's route and length of ride is prescribed long before the trek. This year, it began in Rock Rapids in Iowa's northwest corner and ended in Burlington in the state's southeast corner. Towns are preselected to act as host communities so the bicyclists can sleep in their thousands of tents and eat cheap community-prepared dinners or breakfasts (chicken, cole slaw, potato salad, bread, butter and lemonade for $2 in Rockwell City).

More often than not, RAGBRAI's population dwarfs that of the host town: RAGBRAI (pop. 5,000 plus), Wapello (pop. 1,900). Most baggage is carried in two semi-trailer trucks arranged for by the newspaper.

Startup is at sunup and not before. The state police patrols (four of them) frown on riding in the dark. Between sunup and an hour later, thousands of bicyclists bunch together. But as the day wears on and people stop to eat or drink or swim or shade, the bunch begins to stretch like a rolling rubber band until it is 30 or more miles long.

Ambulances travel back and forth along the route, as do bicycle repair vehicles and so-called "sag" wagons which pick up the lame and halt and bone-weary and deposit them at the next host town. Finally, somewhere on alternate routes is a convoy of hundreds of recreation vehicles racing to the next campground to await their two-wheeled friends and relatives.

All along the route, civic and church and youth groups sell fruit and drink; whole towns cooperate to prepare and sell thousands of lunches; individual farm families sell iced tea and lemonade, cookies and cake, and give away cold water.

The spirit of RAGBRAI takes place at all kinds of levels. The bicyclists themselves represent a universe of subcultures. There are the racers, who, like David Stoller in "Breaking Away," race at sunup 70 miles in two hours and turn around and race back to where I am just mounting my bicycle to begin the day's long ride. They are very young.

Racers do not wear helmets. They wear something that looks like a painter's cap. Wheelmen do wear helmets. These are somewhat older bike freaks who think nothing of riding 100 miles or so on a Sunday at home and probably bicycle to work. The helmets distinguish the racers from the wheelmen. Otherwise, their uniform is the same -- special seamless pants with chamois crotch, special shirt and shoes and strong legs.

But most of those on the ride are just that -- on the ride. They come from many parts of the country and a few from Europe, but most are from Iowa. They are not competing except with themselves.The dress for summer.

Not all sports are democratic. One has to be well coordinated to play baseball and tall to play basketball and strong to play football. Jogging and bird watching are far more democratic. And except for the price of the bicycle, so, too, is bicycling.

You can be short or tall, fat or skinny, any color or nationality. You can lack style or class and still finish 500 miles.

The youngest of the Dubansky family of Story City, Iowa, with whom we rode a few days was seven years old on May 1 and she finished the ride. So did several 78-year-olds. There were farmers (I rested with one who walked away from his farm for RAGBRAI and whose only lament was that he had missed the high price for his corn), blue-collar workers, students, university professors, ministers, housewives and doctors.

The spirit of RAGBRAI is also in the anticipation of Iowa's people. One particularly hot afternoon, my wife and I stopped at a farmhouse for iced tea. We noticed that the farmer and his wife were allowing RAGBRAIers to use the bathroom in their house.We remarked to the wife how incredibly generous it was of her to let hundreds, maybe a thousand, persons traipse through her living room to use her bathroom.

She replied: "Oh, but you have no idea how excited we all have been ever since February when we first learned that RAGBRAI would pass right by our house."

A few days later, in Mackey (pop. 300), the Mackey Methodist Church was selling iced tea and donuts and lemonade and cookies and we stopped for some. We asked one of the church ladies whether RAGBRAI was the biggest thing to hit Mackey. She was pensive for a bit and then said: "Yes, since the blacksmith shop blew up."

Before RAGBRAI, my wife and I had been lax weekend bicylists and had managed a 33-mile day along the C & O Canal and back. My daughter had never ridden beyond 22 miles. But Don Kaul, who works in Washington for his newspaper, assured us RAGBRAI "was a piece of cake" and that "we didn't need much practice" and we "could take our time because we had all day everyday."

Three miles out of Rock Rapids, my wife and I were candidates for intensive care. The first things to go are the fingers. Yes, the fingers. They go numb and stay numb (and still are a month later; thank God I only type with two fingers and am not a dentist). Next to go is the backside, from sitting on hard seats much too small for the human anatomy. Then the thighs. Last to go is the marriage.

My wife did not ride with me on two of the first five days. Oddly enough, I missed her complaining and for stretches, when I rode alone, I quickly got bored talking to myself.

Enough.

There is this to be said about Iowa. It is far hillier than anyone led us to believe. Much of western Iowa looks like much of western Iowa. The country changes a bit in the east but what doesn't change is field after field of corn and soy beans and hogs and hogs and soy beans and corn. Iowans sit on 25 percent of the best land in the country and now they know it.

To be sure, there still is a hesitation with strangers, particularly "easterners." Many Iowans we met, especially the older ones, were a bit apologetic about their residual reputation as hicks. Tom Wolfe, one told me, called Iowa a "fly-over" state. But there is nothing apologetic about younger Iowans.

The younger generation senses it has a large role to play internationally because it grows the food that feeds the hungry. And the state is booming, with healthy balance between industry and agriculture and little unemployment. And so there is a good feeling in Iowa now about itself and its place and its values.

There is this, too, to be said about Iowa. It is one of the cleanest areas anywhere in the world. One can eat off the grass, so to speak. Little wonder, then, that in McCallsburg, Iowa (pop. 300), where we stopped at the post office to mail some cards, there was this notice of zoning action at the July 23 City Council meeting:

"Roger Reisetter was called to the meeting about Elmer Newgaard's house. Roger agreed to clean the house and it's surroundings up.

"The Conservation Commission attended the meeting, asking about the complaint of the weeds at the northwest end of town. Procedures will be taken to rid the city of these weeds."

Iowa is young, especially the northwest corner, where many towns celebrated their centennial when the rest of the country was celebrating its bicentennial.

Iowa is gracious and hospitable.

So, will we return for RAGBRAI VIII?

Will Jimmy Carter be reelected?

Will the heavily armed Russians leave Cuba?

Will I call my mother?