In good weather, I like to ride my bike on rail trails. The occasional dust, mud or mine drainage is still better than the potholes and Alpine hills of the public streets.

The rail trails are nearly flat, smooth … ish, and wind through lovely landscapes of rocks, rivers, forests and shooting clubs, where the cracks of gunfire really motivate you to squeeze the last sprint out of your tired legs.

There is also a great deal of wildlife to be seen out on the trails, some of it not on bicycles. I've seen deer, groundhogs, zillions of rabbits and chipmunks, even a family of skunks.

I've also seen a few snakes. If you scan the trail up ahead and see a stick that's moving, it really sends a chill up your fork.

Usually, when you roll up close enough to want to pull your feet up onto the bike frame, you see the conservative pinstriping of a garter snake. They're one of the most common snakes, and you or someone you avoid at high school reunions probably used to catch them.

Less than 3 feet long, skinny, effectively nonvenomous -- if you have to get your ankles near a snake, you probably want it to be a garter snake. They're kind of the mall cops of the herpetological world.

According to the state Fish and Boat Commission Web site, there are 18 species of nonvenomous snakes in Pennsylvania, seven of which are indigenous to the state Legislature. The others live in brush piles, stone walls, campground port-a-johns and, of course, planes.

There are three species of venomous snakes native to Pennsylvania. I had heard tell of copperheads, but I didn't know about the other two.

The other two are rattlesnakes. And I saw my first Pennsylvania rattlesnake last weekend. (If it saw me, it didn't say anything.)

There was a knot of people standing in the middle of the Youghiogheny River Trail a little way outside Ohiopyle, which usually means one of three things:

1. Someone has fallen off a bicycle.

2. There is something to see: a rainbow, a family of deer, a nude sunbather.

3. They are exchanging gorp recipes.

As I braked and rolled up to them, I saw something snaking across the trail.

"Rattlesnake," said a voice that seemed to know what it was talking about.

I couldn't have been any more startled if he had said "kangaroo."

But by golly, there it was: a little turned up conical rattle at the very end of a very long and rather thick snake.

People at the back of the crowds -- one inbound, one outbound, divided by a snaky line 3 1/2 or 4 feet long -- were flagging down trail traffic as it arrived, so there were probably six or eight people on each side. We all stood there in our Lycra, staring, our Vitaminwater getting warm.

The rattlesnake was not rattling. I didn't know whether to be relieved or disappointed. Very few people get bitten by poisonous snakes in Pennsylvania, because the snakes are not really aggressive -- and most Pennsylvanians are smart enough not to poke a rattlesnake with a stick. Or a bicycle pump.

This rattler ignored us entirely. It seemed to have no idea how close it must have come to being a speed bump. It slowly pushed itself off the trail and disappeared among the leaves, perhaps to keep a dinner appointment with one of the chipmunks I'd seen earlier.

"Isn't it beautiful?" the cyclists asked one another. They reached in their handlebar bags and pulled out cameras. They exchanged gorp recipes.

I'm sure things would have been different if the snake had been coiled up and rattling at the children, but, far from being frightened or running away squealing, everyone seemed to feel we had been privileged to see a wonder.

Like a rainbow. Or a nude sunbather.