Mountain Bike Size Calculator 29 Er. You can read about the different bike types here. Effective top tube (ETT) describes the horizontal distance between the head tube and the seat tube, regardless of whether you have a straight top tube or one that slopes down.
Mountain bikes are generally measured in frame size (inches), which is the distance from the center of the crank to the top of the frame at the seat tube. More momentum, more stability, better traction. A bigger wheel is a faster wheel.
You will get more stability and momentum as well as better traction with these bikes on off-road.
MTB's are engineered for off-road riding.
Mountain bike sizing can be affected by suspension and your tire choices. First, consider what kind of bike you want. So, make sure you look at a tire size chart and try a full-suspension mountain bike for size before buying.