When people talk of the Shenandoah River they are usually referring to the popular South Fork, plus the main body of the river that runs north to the Potomac. The lesser-traveled North Fork flows through beautiful countryside on the west side of the Shenandoah Valley, where from Edinburg to Strasburg it tightly meanders for about 100 miles in the space of just 20 road miles. At good water levels it may be navigable from as far upstream as the Brocks Gap area near the VA/WV state line.
A fairly easy 11-mile day trip is to float the lower section of the North Fork from Strasburg to Riverton/Front Royal. This section is not as rural as further upriver, but still scenic, with a postcard view of the north end of Massanutten Mountain and Signal Knob on river right. The first half of this trip is reminiscent of the South Fork, with greenish-colored water framed by trees on both sides, and river-wide karst ledges just under the surface. The North Fork completes its last few meanders here, and Cedar Creek flows in from the north (an awesome paddle stream in its own right).
Halfway through the trip you'll encounter a weir that impounds water for the town of Winchester (there are warning signs well in advance). The river is shallow and the little dam is short enough for the brave to run it through a break in the center of the river, but to be safe, portage it on the left. Good spot for a break too, as the remaining land downstream is mostly private.
After this point the river straightens out as it heads eastward to merge with the South Fork Shenandoah. The occasional Class I ripple and a few rocks to dodge keep it interesting. The bucolic scenery is interrupted by an RV park on river right at a shoals area; in summer you may encounter tubers floating here and a bit of a party going on. After that the river is quiet and the current runs out as you approach the Riverton Dam. This is a MUST-portage dam that is supposed to be removed in 2010. There is plenty of warning, and a portage ramp and trail on river right just before the highway bridge. After a 25-rod portage, put back in below the dam and ferry across to the boat ramp. (Stay downstream of the little island and well away from the hydraulic of the dam.) At a historical marker nearby you can read about the Civil War engagement at Guard Hill.
None, other than at the Town Park at the start. Before the trip you might want to hit Big & Lil D's Diner for breakfast or lunch, just 2 blocks up from the park on Queen St.
To the takeout at Riverton:take I-66 to exit 6, go south on US-340/522 (Winchester Rd) for 1 mile, turn left on Riverton Rd.
To the put-in at Strasburg:
Cross over the river going south on the US-340/522 bridge, then turn right on VA-55. After 9 miles, turn left on Park Rd just before you reach the warehouses. Cross over the train tracks, and follow Park Rd on the other side (slight right then left) into the Town Park.
Ample free parking and easy put-in at Strasburg Town Park (38.974N, 78.351W).
An alternate put-in 6 miles further upstream is at Deer Rapids Rd (38.955N, 78.375W).
Take out at the DGIF ramp in Riverton (38.950N, 78.198W). This ramp/lot can be busy on weekends since it is used as an access point for fishing and pleasure boats on the main Shenandoah.
UPDATE: As of Nov. 2010 the Riverton Dam has been demolished and removed. Paddlers can safely float to the public ramp takeout near the US-340/522 bridge without having to portage.
Virginia DGIF website
Ed Grove's book, "Classic Virginia Rivers" discusses the North Fork Shenandoah, but doesn't say much about this last stretch.