Opposite of concave . A geometric shape is convex if all its edges point outwards. That is no part of it curves or faces inwards. If a shape is convex, a line segment drawn between any two points on the shape will always lie inside the shape. The figure above is a convex pentagon. No part of it is caved in and any line segment, such as the red one shown, linking two points on it always lies inside the shape. See also Concave definition.
Recumbent bicycle. A recumbent bicycle is a bicycle that places the rider in a laid-back reclining position. Most recumbent riders choose this type of design for ergonomic reasons; the rider's weight is distributed comfortably over a larger area, supported by back and buttocks. On a traditional upright bicycle, the body weight rests entirely on a small portion of the sitting bones, the feet, and the hands. Most recumbent models also have an aerodynamic advantage; the reclined, legs-forward position of the ...
A man riding a recumbent bike. Photo Credit: Huntstock/DisabilityImages/Getty Images A recumbent bike is a cardiovascular machine that gives you a similar workout to a regular exercise bike. The difference is with the way the bike is set up. On a recumbent bike, there is a bucket seat with a backrest. The pedals are out in front of you, so when you operate the machine, you are in a horizontal position. This can take pressure off your lower back and prevent you from slouching. Even though the bike is a piece of aerobic equipment, there are multiple muscles that you will work when you use one. Video of the Day