North Fork is an uphill grind, but one of the most beautiful uphills you'll ever experience. You pass a handful of gorgeous waterfalls, including the impressive Tumalo Falls.
The trail is mostly smooth, but there are a number of roots, and a few rocky obstacles. Also, a few skinnies (log crossings). The first one that crosses Tumalo Creek is not recommended for riding. The last one (near the end of the trail) is totally doable, but surprises you with an actual drop-off, rather than a log ramp!
In summer months, there are many bikers and hikers. It's a beautiful spot to be in nature!