Focusing on Frame Dimensions

If your local bike shop determines that you need a certain size frame, they’ll still need to have you sit on the bike to confirm that the frame’s dimensions suit your body type. Two 20-inch frames can vary significantly based on the dimensions in which they were manufactured. A shorter version of a 20-inch frame will provide greater performance and handling; in this case, the seat tube will be more upright, requiring you to sit in a more aerodynamic, bent — over position. Another 20-inch frame may have a longer base to provide sta­bility and comfort and a more sloped seat-tube angle for a more upright ride, both of which provide benefits when touring.

As a general rule, when you’re seated on a bike with your hands on the handlebars and feet on the pedals, the handlebars should block your view of the front hub. Another rule of thumb is that in your natural reach, your arms should make a 90-degree angle to your torso. On road drop handlebars, of the three holding positions, the middle lean (hands over brake levers) should obscure the hub with the handlebars.

In general, you shouldn’t be stretched out like Lance Armstrong or sitting upright like you’re getting a haircut. There should be a slight bend in your elbows and they shouldn’t be locked out or pressed into your ribs.

If the top tube is slightly too long or short, this can be compensated for by adjusting the stem length. The stem can be raised or lowered; with adjustable stems, the angle can be adjusted as well.

Positioning Your Handlebars

The handlebars are one of the three points where your body comes into con­tact with your bike, so you need to take the time to set them in the position that’s most comfortable for you.

Before adjusting your handlebars, make sure you’ve found the appropriate height and angle for your saddle. If you don’t have the saddle in the proper position, you won’t be able to set the handlebars correctly.

For most everyday riders, the handlebars should be even with or slightly higher than the seat. When you sit on the bike and grab the uppermost part of the handlebars and straighten your arms, your back should be at a 45-degree position. If you’re looking for a more aerodynamic position, the bar should be an inch or two lower than the saddle. In this position, the angle of your back will be less than 45 degrees.

The height of the handlebars is sometimes limited by the type of stem you have. On some threadless stems, spacers can be used to adjust the height.

If this doesn’t provide enough of a change, you can replace the stem with an adjustable one that provides more range to move the handlebars.

For road bikes with dropdown handlebars, the other adjustment to con­sider is the angle. The traditional approach was to have the bottom of the handlebars line up parallel to the top tube. But if you don’t want to be bent over in a position better left to yoga classes, a more appropriate angle is for the bottom of the handlebars to be closer to parallel with the seat stays, as shown in Figure 19-4.

Figure 19-4: The proper handlebar angle.