One of the longest and steadiest mountain biking trails in Utah, the Rail Trail is perfect for anyone looking for a long cruise on their mountain bikes, horses, or on foot. While doing the whole thing might be difficult, it doesn't get much easier in small doses. Following the route of the former Union Pacific Rail Line, it runs for 28 miles along a relatively flat and packed dirt doubletrack.
If you start in Park City, the first 3 miles can be ridden on your beach cruiser, skateboards, Rollerblades, or jogging strollers as far as Highway 248, thanks to the nicely paved surface. After that point you'll want to be on a mountain bike, but it's still a nice pack. After you pass Wanship. the Weber River hugs the trail, and it's really quite beautiful. As you pass Coalville on the way to Echo Reservoir, the trail gets more rugged, but you now ride just yards from the water. There are large cottonwood trees providing afternoon shade near Echo, but most the trail is very exposed.
There are seven total trailheads from north to south at Echo Reservoir, the town of Coalville, the town of Wanship, the Promontory development, Quinn's Junction, Prospector Park, and Park City. The elevation change is 1,200 feet between the Echo Trailhead, the low point, and the Park City Trailhead, the peak. If you are doing a one-way shuttle, it is much easier to start in Park City. While the downhill grade is slight, you can definitely feel it helping compared to going the opposite direction. There are several historical interpretive signs along the way as well.
A decent medium-length ride is done by starting out from the Park City or Prospector trailheads and turning around at Pace Ranch, just before the I-80. If you turn around here you will do about 15 miles total. That is a good after-work ride in this area, and it's not technical. There are great birdwatching opportunities here; be sure to keep an eye out for cranes. Watch out for the cow pies and for some deep ruts in parts of the track along the way. There are bathrooms at Coalville, Wanship, Promontory, and Quinn trailheads only, and there is a tire gauge and pump about a mile down from Prospector. One of the annoying parts of this trail after this point is there are a lot of stops. The highway crossing is followed by multiple cattle gates that you need to open and close behind you. It definitely stops the flow, but at least there are long stretches without any gates. Once you pass Promontory, it's smooth sailing
If you want to have a more nature-oriented ride, cross over and under cool wooden bridges, then consider the section between Coalville and Wanship. The Weber River is right nearby and a great place to test out your fly fishing skills. There are A-frame steps to get over the barbed wire fences and give you river access. There are far fewer people using the trail in the northern sections than those closer to Park City. Most people don't do the whole trail but usually do one section depending on where they live. If you want solitude and nature, then hang in the northern parts, and if you want it to be paved and near town, then Park City is best for you. Dogs are allowed on leashes.