December 6, 2014
It's more like a 3.5, but I'm rounding up because its convenient by proximity to where I live. If you park at the Star Market in Waverly Square (Belmont), you can cross the street (Route 60) and step into the forest, picking up the coal road and begin climbing your way towards the water tower. Most people park at the Lone Tree Hill lot, but I like getting in the extra warm up and extra mileage.
If you take the trail to its terminus on Beaver Street in Waltham, you'll get in a solid 8 miles, and then you can bike back to wherever you parked for a good, solid loop.
It's beginner to intermediate and can be made more challenging if you choose to hit some jumps or beat your previous time.