I checked out the Tolt-Pipeline trail a few months ago in search of a nice gravel ride not too far from the city. I read the prior reviews stating that it was pretty hilly and not good for children. Feeling I'm a pretty "fit" cyclist, I threw caution to the wind in hopes of a good scenic work-out. I started from the baseball fields where there's easy access to the Tolt-Pipeline trail via the Sammamish River Trail. To save a headache, take a right onto the trail from the parking lot, or else you'll be heading the opposite direction which takes you down by the waterfront. As you pedal along the Sammamish river trail, look for a sign (I believe it says "Tolt-Pipeline Trail") and dirt road that branches off to your right. Traverse the dirt road and cross the busy street at the end. The next part is arguably the most difficult part of the trail, where you'll proceed up a pretty steep grade with your bike over your shoulder. This part had me confused as this wasn't mentioned in any of the reviews and I felt like it was intense enough of a climb with a bike that it should have been, so maybe there's an easier way to access the trail further up somewhere. Once you reach the top you're greeted with a wide gravel road and rolling hills. This trail navigates past multiple farms which makes for an enjoyable experience. Chances are you'll be sharing the road with horses, so make sure not to spook 'em. The remaining hills, while not as intense as the first, will have you out of the saddle most of the time in granny-gear, so be warned. I would not recommend doing this on a skinny tire! The gravel is course here. I was on a road bike with medium 650b tires and was wishing they were wider at points. The trail mellows out at points and there's a few scenic stops ("Bear Creek" comes to mind, which is about the point I decided to turn around). On my way out I encountered some unsavory folk hanging out on the concrete driveway that you cross over on that big initial hike-a-bike hill-climb. I had decided to ride down the steep grade, which given my bike has side-pulls it wasn't the smartest decision, but I was up for it. As I got towards the concrete driveway I had released the brakes to jet past the guys I was convinced were going to try and jump me (it was pretty obvious they were up to no good and waiting for me to come down...) I had gained so much momentum from that I had barely stopped before hitting the gate at the bottom. So, words of advice: fat tires and disc brakes are a plus, but not necessary, carry pepper spray or bring your martial arts a-game, and be prepared for some steep grades! Have fun!