When selecting a new bicycle, the correct choice of frame size is a very important safety consideration. The ideal clearance will vary between types of bicycles and rider preference. This makes straddling the frame when off the saddle easier and safer in situations such as sudden traffic stops.
Notes
There should be a clearance of no less than 1-2 inches between the groin area of the intended rider and the top tube of the bicycle, while the rider straddles the bicycle with both feet flat on the ground.
The seat post "minimum insertion" / "maximum height" mark should not be visible when the seat post is inserted into the seat mast of the bike. do not raise the seat post beyond this mark. the seat post or frame may break causing you to lose control and fall. Always check to make sure the seat post adjusting mechanism is tightened securely before riding.