A singletrack magazine is a really cool magazine that talks all about mountain biking. Mountain biking is like riding your bike on dirt trails instead of on the sidewalk or in the street.
The magazine has pictures and stories about people who ride their bikes in the mountains. They talk about different places to ride and what kind of gear you need to be safe. They also talk about how to make your bike go faster and how to jump off of things without hurting yourself.
Singletrack magazine is like a big book that comes out every few months that you can read if you like to ride your bike in the mountains or if you just think it sounds fun.