FRANKLIN -- With the growing network of bike trails near this Venango County seat, gasoline isn't required for touring the birthplace of the nation's petroleum industry.

Curt Chandler, Post-Gazette photos The Belmar Bridge spans a 1,385-foot gap over the Allegheny River, providing the occasional glimpse of canoers floating downstream far below (see photo below) and giving access to Sandy Creek and Allegheny River recreation trails. Click photo for larger image. Hitting the Trails This is part of a weekly series spotlighting hiking and biking trails in the region. Publication of the series coincides with the Hike for Health project promoted by the state Department of Conservation and Natural Resources, state Department of Health and other agencies to encourage folks to get fit on foot. The DCNR has additional information on this week's journey on the Sandy Creek, Allegheny River and Justus trails. Related content If you go: Franklin trails More photos from this story Previous stories Find previous installments of this series at our Hitting the Trails Index More pictures from all the stories in this series: Hitting the Trails Photo Journal Next week Boyce Mayview Park in Upper St. Clair Click photo for larger image.

Franklin is both a charming river town 85 miles north of Pittsburgh, and the perfect access point for 35 miles of paved bike trails that provide glimpses of the region's oil heritage.

In 1859, the first commercial oil well was drilled near Titusville, about 20 miles north of Franklin, and the area is dotted with relics of the 19th-century oil boom. On the Allegheny River Trail, just east of town, cyclists pass near the third oil well ever drilled, and a well drilled by John Wilkes Booth about one year before he assassinated President Lincoln.

Much of this intriguing history goes unmarked for now, but interpretive signs are in the works. Meanwhile, nature takes center stage, at least during the summer.

"When the leaves are down in the fall and winter, you can see evidence of pumping jacks all over," said Jim Holden, president of the Allegheny Valley Trails Association. "There are a few active oil wells there now, although the owner hasn't pumped since we've had a trail there."

My wife and I started our journey from a trailhead on the east side of the Allegheny River, which is the far side of Franklin if you approach from Pittsburgh along Route 8. You can rent bikes, canoes and kayaks here at a store called Country Pedalers, and find information on trails and nearby attractions at the Salt Box Visitor Center.

After consulting a trail map, we biked one mile back to a Subway sandwich shop in town, where we filled up on alternative fuel.

Back at the trailhead, we could have followed the Samuel Justus Recreational Trail north for six miles to Oil City, but we decided to go south toward Belmar.

The trail traces the east bank of the river as it meanders east and south. There's traffic noise from Route 322 during the first mile, but it soon yields to the sounds of songbirds and tributary streams.

This used to be the Allegheny Valley Railroad, which followed the river north from Pittsburgh and reached Franklin in 1868. Eventually, the line went to Olean, N.Y., where trains could switch tracks and go to Buffalo.

Now, butterflies seem to be the most frequent travelers on the trail. The panoramic views of the river from the trail included oil slicks, back in the day. As early as 1790, prospectors skimmed oil from the Allegheny and nearby French and Oil creeks and studied whether it could substitute for whale oil burned in lamps.

Five miles downstream from Franklin, the trail passes beneath the massive Belmar Bridge, which at 1,380 feet is longer than the Veterans Bridge in Pittsburgh. It was built in 1907 and carried a railroad that local oil man Charles Miller and John D. Rockefeller hoped would connect New York and Chicago. The line's ultimate fate wasn't so glorious, as it served primarily for hauling Clarion County coal to Ashtabula, Ohio, on Lake Erie.

A steep ramp leads to the bridge and the Sandy Creek Trail, nearly eight miles long. It's a tough climb, but the payoff is grand.

We started by riding across the bridge so we could view the river valley from above (and use a Port-A-John on the west bank). Back on the east side of the river, the smell of pine trees alongside the trail is so pleasantly distracting that I wanted to stop pedaling.

Keep going for spectacular views from five high bridges that take the trail over the creek. About two miles from the Allegheny, the trail passes through one of the scarier tunnels you'll find on a bike path. You'll have to brave gaping holes in the tunnel liner, water dripping from the ceiling and debris all about. But the tunnel structure itself is sound, and the liner is to be repaired this fall.

After traveling another mile or so, we stopped at a bench to rest, and then decided to turn back. We regretted missing the rest of the Sandy Creek Trail, as well as the Allegheny River Trail south of Belmar, which last year was extended through tunnels so long you need a lamp. We also missed Indian Guide Rock, which bears more than 50 carvings that were made by Native Americans between 1200 and 1750 AD.

Alas, we were running low on fuel. So we pedaled back to Franklin for some ice cream.