Head tube angle: Head tube angle
is the measurement in degrees at which
the head tube points towards the ground.
A 90-degree head tube angle would be
straight up and down. Think of a shopping
cart with the wheels spinning in circles.
Bikes use head tube angles ranging
from 72 to 63 degrees. The difference
in degrees causes a dramatic difference
in the way the bike handles. Bikes with a
steeper angle will have quicker steering
and better climbing capabilities. A bike with
a slacker angle will have slower steering
and more stability at high speeds (think
chopper). Cross-country bikes benefit more
from steeper angles ranging from 69 to 72
degrees, while a full-on downhill bike will
have a slacker angle between 63 and 65
degrees. A trailbike’s head tube angle can
vary from 66 to 68 degrees, depending on
its intended purpose.
Chainstay length: A bike’s chainstay
is the lower part of the rear triangle with
a horizontal connection to the rear wheel.
Chainstay length plays a major role in the
playfulness of a bike. A bike with shorter
16- to 17-inch chainstays will wheelie
and manual better than a bike with lon-
ger stays. Cornering is also improved
with short chainstays due to a shortened
wheelbase. If the chainstays are too short,
however, it can cause problems. Slightly
longer chainstays will help keep the front
wheel planted on the ground during steep
climbs, and the increased wheelbase can
add stability at high speeds. Chainstay
length should be chosen carefully in order
to achieve the right balance.
Bottom bracket height: Bottom bracket height is the measurement from the
center of the bottom bracket to the ground.
A lower height will result in better cornering due to a lower center of gravity. Bikes
with super-low bottom brackets, however,
will often have clearance issues with the