Frame measurement is the key to bike sizing.Stand-over height and top tube length must suit the rider's inseam as well as torso and arm length. Frame size is usually measured from the center of the bottom bracket to the center (or top) of the top tube where it joins the seat tube (the vertical tube that holds the seat post): in centimeters for road bikes, inches for hybrid and mountain bikes.

To do a quick sizing, stand over the bike straddling the top tube with both feet flat on the floor, shoulder width apart. Lift the bike by the handlebar and saddle as far off the ground as is comfortable. With a rod bike, you want 1 to 2 inches of clearance between the tires and the floor. For mountain or hybrid bike, there should be 3 to 4 inches. A rider should be able to reach the handlebar comfortably. When sitting on the saddle and holding the handlebar, the cyclist should not be too stretched out, or too hunched or cramped.

SADDLE HEIGHT - With the ball of the foot on the pedal, there should be a slight bend in the knee when the pedal is at the very bottom of the pedal stroke. If your hips rock when pedaling, the seat is too high. Recumbent bicycles, leg extension is the best judge of frame size.

The saddle should be level, not pointing down or up. Any slant to your saddle puts unnecessary pressure on your pelvis, torso and arms.

The forward or backward position of the saddle should be adjusted so that your knee is directly above the pedal spindle when the cranks are horizontal.

Handlebars come in a variety of shapes and sizes. You should select handlebars that are approximately the same width as your shoulders or wider. For drop bars, handlebar angle should be adjusted for comfort on the tops. For flat or riser bars, position to ride with slightly bent elbows and a straight line from forearms through the wrists.

For drop bars, adjust for comfortable reach. The rider should be able to apply the brakes in the forward position and maintain a comfortable hand position on brake hoods. Brake lever adjustment cannot be done without unwrapping and re-wrapping handlebar tape. For flat bars or riser bars, the angle and reach of the levers can be adjusted easily.Additional adjustments may enhance your riding pleasure. These may require new components.

Length and rise should be determined by riding style. Generally, longer and lower for more aggressive riders, shorter and higher for more relaxed riders.

While platform pedals suit many people, toe clips or clipless pedals (with cleats that lock onto the pedals) keep feet aligned on the pedals, help you produce more power with each stroke, keep your feet from slipping off the pedals, and make it easier to raise a pedal when stopped.

Different crankarm lengths, chainring combinations and crank materials are available.