Chassis: A fancy term that refers to the frame, fork and suspension as
one unit, or that can be used to describe the frame onl
Chassis: A fancy term that refers to the
frame, fork and suspension as one unit, or that can be used to describe the
frame only.
Headtube: The tube in the front part of the frame that the fork passes
through.
Headset: A pair of ball-bearing assemblies, pressed into the head tube,
that the fork rotates on.
Top tube: The upper member of a conventional frame. Its length
determines the proper fit for different sized riders.
Down tube: The lower member of a conventional frame.
Gusset: Any reinforcement that is added to a frame tube that serves to
strengthen it. Gussets are normally found under the downtube/head tube
junction.
Water bottle bosses (bottle mounts): Threaded fittings that fit bolts
for water bottle cages.
Bottom bracket shell: The lowermost tube of the frame that houses the
crank axle mechanism can be either 68mm or 73mm wide. The left side is threaded
clockwise (the standard direction); the right side is threaded counterclockwise.
Bottom bracket: An ancient name for the axle, bearings and bearing
housing that the crankset rotates around. There are three main designs: A—Square taper (the industry
standard). B—Shimano splined axle (fits upper-level Shimano cranks). C—ISIS splined axle (fits Race Face, Truvativ, FSA and other aftermarket
cranksets).
Seat tube: The frame member between the bottom bracket and the top tube
that the seatpost is inserted into.
Interrupted seat tube: A frame that uses a short seat tube that does not
continue to the bottom bracket—typically used to make room for rear suspension.
E.G. Specialized Big Hit, Stumpjumper FSR
Cable guides: Any of a number of fittings that are attached to the frame
to route cables, cable housings and brake hoses.
Brake bosses: Threaded posts attached to the frame and fork that act as
pivots for caliper brakes.
Seatpost: The tubular part sized to slide
into the seat tube that allows you to adjust the position and angle of the
saddle.
Seatpost clamp: An clamp that fixes the height of the seatpost. Many
bikes use a quick-release mechanism here to lower the seat for technical
riding.
Chainstays: The lower pair of tubes that connect the frame to the rear
wheel.
Swingarm: The lower frame member of a rear suspension system that spans
from the bottom bracket to the rear wheel; performs the same function as
chainstays.
Rear dropouts: The fittings that secure the rear wheel’s axle and the
rear derailleur to the frame.
Seatstays: A pair of tubes that span between the rear axle and the upper
part of the frame, or its counterpart in a rear suspension system.
Caliper
mount: A rigid
fitting that fixes a disc brake caliper to a frame or fork. There are two
different types: A—A-type mounts: (A side-mount flange that fits most disc brake types)
B—Post mount:(A pair of
threaded bosses that fit the underside of Hayes-type calipers.)
Butted tubing: Any tube with walls that are thicker near the ends than
in the center. Taper-butting is the same process, except that the end segments
have a gradient in the thick sections.
Swaged tubing: A mechanical operation that forces a section of a tube to
be larger in diameter. Swaging also can be used to change the shape of a tube
to a taper, rectangle, ect.
Hardtail: A bicycle equipped with a suspension fork that has a
conventional, unsuspended frame.
Softtail: A dual-suspension bicycle with minimal rear wheel travel. Most
use a simple spring instead of a hydraulic shock and use frame flex instead of
mechanical pivots to actuate the rear suspension.
Monocoque: A frame member that uses a hollow, box-shaped structure
instead of tubing or a solid bar to carry the load. Monocoque frames are
usually aluminum or composite construction.
Dropped top tube: A tube that is bent in the center, or made in two pieces to
create more stand-over clearance for the rider.
Seat mast: The frame member that supports the short seat tube on an
interrupted-seat-tube frame design.
