I warned them about those Great Allegheny Passage tunnels. Make sure you get off the bikes and walk, I told my dozen cycling companions. Did they heed my advice?

Not much. Most plunged into the disorienting void, one wearing sunglasses no less, gazing through dark lenses upon what was already dark. Expressions of concern, let us say, echoed off the walls.

I flashed back to a friend's mid-tunnel wipeout a year earlier. Were they all going down?

The episode proved to be a harmless hiccup in a gem of a cycle trip.

The Great Allegheny Passage (GAP) between Pittsburgh and the Western Maryland town of Cumberland is a smooth-rolling romp through the mountains that pleases cyclists of varying ability and just glows on fine autumn days.

It does not have much in the way of hazards, if you'll just listen to me and walk when I tell you.

It stretches 227 kilometers, offering sparkling river views enlivened by the screeches of whitewater rafters. It gives you a passing panorama of wind-farm turbines beating lazy arcs and loads upon loads of peace and quiet.

The GAP links up with the Chesapeake & Ohio Canal towpath in Cumberland, which then carries on to Washington DC, 298 kilometers away. The C&O trail is rougher and wilder but there's no slam-dunk case that one is more beautiful than the other. They're different, and together form a 525-kilometer off-road expedition without parallel in the United States.

Great Allegheny is getting the buzz because it's newer, more carefully maintained and growing. The recent completion of a 13-kilometer section connects the trail to the old steel town of Homestead on Pittsburgh's outskirts, leaving just one section to be finished to link with downtown.

It's also a family-friendlier trail, much less apt to rattle your eyeballs than the venerable C&O, faster to dry out after rain and more suited to short rides near fun towns. Among them, in Pennsylvania, Ohiopyle is a vibrant intersection for river lovers, cyclists, hikers and campers dseep into fall.

Even so, an end-to-end ride on the GAP requires careful planning.

Skip one lunch opportunity and you may not find another for a long way. Refilling water bottles can be hit and miss.

Accommodation is well-spaced for doing the trail in three or four days but not numerous.

And at the end, finding a way back to cars, the train or the airport is a logistical knot that throws many people.

Here's how we did it this past summer (though the trail makes a fine destination for autumn rides, too)

Day 1: Homestead to Connellsville, Pennsylvania, 80km

Grouseland Tours, chosen because of its rain-date flexibility and rates (US$50 each in groups of four) picked us up in Cumberland, where multiday parking is free by the Amtrak train station, and shuttled us nearly three hours to Homestead.

The trail's early progress goes from rust to rustic, winding through old industrial tracts before swinging off into pastoral lands of the Youghiogheny River, your glittering companion for miles to come.

Lunch 40 kilometers miles later was at the Trailside Cafe in West Newton, one of the few options this day, and a good one. It sits over a bicycle shop, to boot.

Still on the Pennsylvania side, in Connellsville at day's end, we scattered to four B&Bs booked months earlier, none large enough to hold us all. The Victorian Rose - www.thevictorianrosebedandbreakfast.com - and quilt-themed Seams Like Home - www.seamslikehomeretreat.com - were a little outside of town; the owners picked up their guests and bikes. Downtown, the Connellsville B&B - www.connellsvillebedbreakfast.com - hosted the largest number, and its pumpkin-cinnamon pancakes in the morning were a hit. Also in town, the Greenwood House - www.thegreenwoodhouse.com - offered a bare-bones breakfast, the trade-off for a lower price.



Day 2: Connellsville to Rockwood, Pennsylvania, 76km

In no time we're in one of the most remote and gorgeous parts of the ride, a 29-km leg to Ohiopyle, much of it high above the Youghiogheny.

A steady rain begins; you can see it rustling the river but it comes down only as a cooling spritz on your face, under the trail's thick tree canopy. This feels like the heart of the ride.

In Ohiopyle, people are clambering over rocks in shallow rushing water, lollygagging along the river's edge and whooping it up in colorful inflated rafts.

It's bustling place, a destination on its own, but early for lunch so we fill our bottles and move on to Confluence about 17 kilometers away. At this confluence of rivers, the trail leaves the Yock and picks up the Casselman.

You've gained elevation over two days, almost imperceptibly.

Now you feel it, on the last stretch to Rockwood. But take heart: A big reward is ahead the next day.

A thunderstorm nips at our heels, catching some of us riding in the rear while others make it dry to town, only to get drenched there.

Of the Rockwood B&B choices, the Gingerbread House - www.thegingerbreadhousebandb.com - in town and Glade's Pike Inn - www.gladespike.com - outside town are the favorites among the group.



Day 3: Rockwood, Pennsylvania, to Cumberland, Maryland, 71km

If your bed-and-breakfast hosts will pack peanut butter sandwiches, you've got it made.

Otherwise you'll have to do some off-trail climbing to find lunch this day.

The ghostly white wind turbines and valley overlooks are impressive sights in the final uphill going.

Meyersdale is the only trailside town, a vital place to water up. You can get lunch down the hill if needed.

Soon after, it's time for a mini-celebration. You've reached the Eastern Continental Divide. Inside the little tunnel at the divide (you can roll through this one), check the map on the wall, showing how high you've come in three days.

The final 39 kilometers, crossing the state line into Maryland, are a downhill breeze, your closing treat.

But about those last-day tunnels. The Borden Tunnel looks like a cakewalk, which it is, if you walk. Unless you've got a light that cost more than last night's B&B, you'll find everything vanishing from sight except the end, which seems too far away.

Next, Big Savage is much longer but has well-spaced lights, though some are typically out. The last, Brush Tunnel, is like the Borden, out to bite you in the middle.

Clear sailing into Cumberland ends this adventure while teasing you about another. The C&O, that funky old granddaddy of off-road bicycle trails, begins straight ahead.


If you go

About the trail:

Great Allegheny Passage: 227-kilometer rail-trail between Homestead, Pennsylvania, near Pittsburgh, and Cumberland in Western Maryland. For more info, check www.atatrail.org.

Tips:

Starting at the Cumberland end, as many do, gets all climbing out of the way the first day, though it's a slog for nearly 40 kilometers. One cheat: Old-time steam and diesel trains operated by Western Maryland Scenic Railroad run 26 kilometers up the mountain and accept bikes. Schedule at www.wmsr.com.

Some B&Bs are flexible for cyclists who want to reschedule in bad weather, others lock you in as soon as you book or as many as 30 days ahead, so inquire.

The Big Savage Tunnel's giant doors shut for the winter, usually December through March or April, and the road detour is not recommended.