What is the average speed of a mountain bike?

Answer 1

There are plenty of different bike types, plenty of different riding terrains and conditions, and plenty of different fitness levels among the riders - so the question really doesn't make much sense. A fit rider on a road bike in flattish terrain can average 20 MPH w/o trouble, while a MTBer on a technically challenging trail might average 8 MPH. You pick which average you think is more fitting.

Answer 2

That's a pretty pointless question, as it's very much dependent on riding conditions, which can be very different from one ride to another. If it's a really technical singletrack or a climb it can be 6-8 MPH, while a DH run can max out at 40 MPH or so.

Answer 3

There's really no sensible answer to that, as it's too dependent on riding conditions. Can be anything from 8-10 MPH to 15-20 MPH. Like asking for the speed of a SUV, w/o telling if it's at the highway or out on a trail.

Also, the speed of the bike is entirely dependent on the rider. A professional cyclist will have a much higher speed then a beginner. Rider plays a big a role as terrain.