Proper bicycle fit is the single most important factor when
looking for a new bike. Performance, safety and comfort are directly
related to the size of your bike.
Adult bikes come in a variety of frame sizes to fit a variety
of people sizes, smaller people need smaller bikes and larger
people need larger bikes.
Mountain bikes are usually measured in inches, road bikes in
centimeters. All adult mountain
bikes have 26" wheels but have frame sizes from 12" - 24". Road
bikes have 700cm wheels (about 27") and have frame sizes from 38cm
to 65cm. Frames are measured from the center of the bottom bracket
shell to either the top of the seat-tube or to the center of the
top-tube where it intersects the seat tube. (See Figure
A)
The first check for correct frame
size is standover height. Standover height is the basic element of
bike fit. It is the distance from the ground to the top of the top
tube at the point where your crotch would be if you were straddling
the bike standing half way between the saddle and the handlebar
stem. To check for safe standover height, straddle the bike while
wearing the kind of shoes in which you'll be riding. Grab the bike
by the handlebar stem with one hand and the top tube of the frame
behind you with the other hand. Lift the bike straight up off the
ground. You should be able to lift the bike off the ground the
following distances: Road bikes-2", Mountain bikes-3"-4", Hybrid
bikes-2"-3". Some aggressive mountain bike riders ride bikes with
standover height of 4"-6". (see Figure B)
Buying the right size frame guarantees a better
fit. Too large of a frame means too long of a reach
to the handlebar, too small of a frame means too short of a reach to
the bar. Seat posts should be raised to create the proper leg
extension. At the bottom of your pedal stroke, your leg should have
only a slight bend to it (see Figure C). This prevents
you from over extending but puts you at the greatest mechanical
advantage (you'll feel more powerful).
Upper body positons should be a natural, comfortable reach to
the handlebars. Too long of a reach will probably cause lower back
and neck pain. Notice the difference in the upper body positions on
the three different types of bikes below (see Figure
D).
Figure
D
Road Bike
Hybrid
Bike
Mountain Bike
Upper body is more stretched out for more
aerodynamics. There should be a slight bend in the elbow when
the hands are on the brake hoods.
The upper body is in a more upright
position for a more comfortable riding position. Less stress
on the neck and back.
More aggressive than the Hybrid but not
as much as the road bike. Increased weight over the front
wheel for better control of your
steering.
As with proper
leg extension, your upper body should be in the proper position. If
you are not comfortable on your bike, there are minor changes that
can be made to your bike such as stem length and rise or a change in
handlebars. Don't give up hope. If you haven't ridden a bike for a
while, you'll need to be patient until your body adjusts to this new
position. (Most of us are used to sitting in a chair or lying in
bed.) BE PATIENT, YOU WILL ADAPT.... P.S. YOUR BUTTOCKS NEED A
LITTLE TIME TO ADJUST TOO.
Remember:
Your elbows should always have a slight bend to them. Your shoulders
should feel relaxed. Things such as padded bike shorts and gloves
also help in this area.
mountain
bikes have 26" wheels but have frame sizes from 12" - 24". Road
bikes have 700cm wheels (about 27") and have frame sizes from 38cm
to 65cm. Frames are measured from the center of the bottom bracket
shell to either the top of the seat-tube or to the center of the
top-tube where it intersects the seat tube. (See Figure
A)
The first check for correct frame
size is standover height. Standover height is the basic element of
bike fit. It is the distance from the ground to the top of the top
tube at the point where your crotch would be if you were straddling
the bike standing half way between the saddle and the handlebar
stem. To check for safe standover height, straddle the bike while
wearing the kind of shoes in which you'll be riding. Grab the bike
by the handlebar stem with one hand and the top tube of the frame
behind you with the other hand. Lift the bike straight up off the
ground. You should be able to lift the bike off the ground the
following distances: Road bikes-2", Mountain bikes-3"-4", Hybrid
bikes-2"-3". Some aggressive mountain bike riders ride bikes with
standover height of 4"-6". (see Figure B)
Buying the right size frame guarantees a better
fit. Too large of a frame means too long of a reach
to the handlebar, too small of a frame means too short of a reach to
the bar. Seat posts should be raised to create the proper leg
extension. At the bottom of your pedal stroke, your leg should have
only a slight bend to it (see Figure C). This prevents
you from over extending but puts you at the greatest mechanical
advantage (you'll feel more powerful).
