Pipeline is a great trail with a very gradual climb/decent.  A lot of people opt to climb up via Hardscrabble Road and then descend Pipeline.  It is called Pipeline because it parallels an old irrigation pipeline that is no longer in use.  You cross over the semi-exposed pipeline in a few places, but for the most part it is off to the sides or buried.  At the top of this trail you are in the Aspen trees and on single track.  You have a few stream crossing.  The first has a pretty nice little bridge over it, but the drop off either side wouldn’t be fun.  It is ride-able if you are confident in your skills.  If not, just walk it across.  The second crossing is through the stream, but it isn’t deep and I have never encountered any structure that prevented me from riding right through.  Note, it is a rocky stream and gets heavy run off in the spring, so it can change from year to year.  I did once ride it too early and the stream was raging way to fast to ride through, so I had to find a safe place to cross.

Once you come out of the trees and into the valley, it is pretty much a double track that is gradual, but fast.  You can take a right just after coming out of the trees and after the second stream crossing, but it is a very steep climb up over the ridge into Second Gulch.  More people climb Second and then use this connector to drop into Third/Pipeline.

This trail drops you right into the Arroyo Drive parking lot.  From here you can do Turniphead or Bailey’s or simply enjoy smooth bike path back to where ever you need to go.