Summertime at Ski Liberty. The lift ascends the hill and drops its human cargo at the summit. The forecast is snow - in about six months.

Instead of using skis, the downhill racer makes his moves on a two-wheel sled down a 3,400-foot trough called the Alpine Slide.

There are 23 of these slides in North America, all but one - at Raccoon Mountain in Tennessee - at ski resorts, where the essential lift is already built. Compared tothe slide my son and I tried in Fairfield, Pa., there's one longer by just 800 feet, down Bromley Mountain in Vermont.

When we first arrived, squinting at the lift in the distance, we could see the barest of movements as the two-seaters crept up the hill. As for the slide, it didn't look like much. We didn't realize until we rode the lift up that the top half of the slide is hidden by trees - as are its seven successive hairpin curves.

From the Lift, we looked down at the double track of the Alpine Slide. Now and then a sled went too fast, got out of control and jumped the track, but the riders didn't seem to mind.

At the top getting instructions, I asked the attendant about a sign that warns "No racing." He smiled: "Well, what we don't see won't hurt you."

Easing onto the sled, I push off. I move a little slowly and tentatively at first. Picking up speed, it feels like bobsledding as my son and I, on separate but parrell tracks, lean into the turns. I try out the rubber brakes by pulling back on the stick. With the stick at middle position, you just slide on nylon skids. Forward position raises "the craft" and exposes the wheels.

Taking the turns is a little scary at first, and I begin to wonder what I'm doing here. But not for long. I need to concentrate, because there's little margin for error. Leaning forward minimizes wobbling, I find, and widening my eyes and opening my mouth puts me in synch with the slide. I hope no one is watching me and no bugs fly into my mouth.

The curves lead into a straightaway. Half-way down, if you take advantage of it, a bump built into the track can be used to catapult the sled and increase speed. If you choose to ease over the bump, the sled generally leaves the slide for a second anyway. From here on, you can relax - but not too much.

My son and I race each other - it's unavoidable - by holding the sticks almost as far forward as they will go. It's hard not to race when you're on Track 1 and your kid's on Track 2. When you start off together, let's say, it's hard not to notice who's getting ahead of whom. I lose an edge I'd gained on the curves: His straightaway appears to be faster. We hit the rubber tires at the end of the slide simultaneously - thump. We pick up our sleds and, still laughing, head back to the lift.

At the top again, we wait in line for a heavy-set woman and her toddler to get comfortable before sliding off. Their sled crawls down the chute. At the attendant's suggestion, we give them a couple minutes' head start.

We choose our poison: My 12-year-old says, I'll take number 1 now. I think it's more dangerous even though it looks the same."

Then off we go. Although I never hit capacity speed, I flirt with the threshhold in my mind where I would lose my nerve and start to get really scared. On a chicken scale of 10, I am a seven.

I don't realize my son has dropped back until, reaching the bottom, I pass the mother and toddler. I think maybe he had to slow down for them. The little girl's father asks, "Does she want to do it again?" "We were doing fine," the mother says, "until the boy fell off behind us."

I shade my eyes and take in the hillside. No one. An empty sled rolls in. The next sled down Track 1 is occupied by a grown man. Turning to him, I say, half-jokingly, "I lost a son up there somewhere." "Yeah," he replies, helpfully. "Well, how did he fall? Did you see him? "No, I just saw the empty sled come down."

Moments later, my son is striding down at the hillside. His pride is bruised and there are two nickel-size brush burns on his left knee.

No serious damage, so we go a few more times. We're on all-you-can-ride tickets. On the lift uphill, my son says to me, "Mom, you're acting like - You know what you're acting like? - a kid."

My last ride is coming up - the unlimited ticket expires soon. Relaxing on the lift, I smell the summertime sweetness of the trees and almost doze off.

Feeling like an expert, I take the ride down easily - until just before the bump, when the sleds starts to wobble. Before I realize what has happened, the sled and I have separated and I am sliding on my left side. I come to a halt minus four inches of skin on my forearm and two inches on my knee. I hurt.

My right leg is still on the sled. I look behind me. No one coming. There's only one thing to do: I climb back on, heading home. My son has fallen off, too, and has two little brush burns on his other knee.

"They just keep going till they get scraped up," the attendant said as he helped me from my sled. He took us both into a little house I hadn't noticed before and slathered our sores with some stingy Betadine.

As my son and I limped away, some young men were calling to the attendant, "Just give him something for his pain." We looked to see another casualty.

His name was Bruce Robbins, and his forearm was bleeding. He was there on a weekday because he works nights, unloading United Parcel Service trucks in Baltimore.

Last time he came to Ski Liberty was four days ago. He wiped out then, too, he said, and today he just reopened the scabs. He and his five friends, all in their early 20s, seem made for the slide.

The guys were finished for the day and going to a friend's for a beer. "When you coming back? I called, "Next week." "You're crazy!" They laughed. "We don't have anything else to do!"