Okay, so you know how you love riding your bike outside? Mixed terrain cycling is when you ride your bike on different kinds of surfaces. Sometimes you might ride on a smooth road, but other times you might go on a bumpy path or even a dirt road.
When people go on a mixed terrain bike trip, they usually bring special bikes that work better on all those different surfaces. They might have bigger tires with more grip, and some bikes even have shocks to help absorb bumps and make the ride smoother.
Some people even bring special bags that attach to their bikes to carry all their stuff, like clothes and snacks and camping gear. They might ride for a long time, stopping to camp outside at night and then riding again in the morning.
It's a really fun way to explore different places and get some exercise too. Just make sure you wear a helmet and stay safe on the different terrain!