When riding from Sycamore South back to the northern parking lot, cross the bridge over Beaver Creek on the Trestle to Trestle paved trail and then turn right (east) about 20 feet north of the bridge and make the steep drop down to the trail (There is an easier option by riding about 50 feet further north). The trail follows along the edge of Beaver Creek for about 1/3 mile before going under the bridge at Beaver Road.
After going under the bridge, the trail splits. Follow the trail to the right and stay adjacent to Beaver Creek. This section is fun as you dodge through the trees and pass over two narrow bridges. Make your way up a small hill with some broken asphalt chunks in it, then back down and through the trees again after turning north along the Des Moines River. There are some rolling up and down areas here and one old concrete mosaic porch you can jump if your skills are adequate.
Just after this section, the trail splits again and you can take the shortcut by going straight. The shortcut includes a huge log over with ramps on each side, or you can turn left and head through a very fun section of rollers and twisting tighter turns. Heading north, you'll come to an open section where the east side and west side trails share the trail. Ride through this and when the trail splits again, take the right trail down a fun sandy grade. This section is very fun with a few uphills and a small rocky drop. There are a few more trail splits, but if you always turn right you'll work your way back to the north parking lot.