Bicycle Archive · Specification report

2004 GT Mach 1 Jr.

Velopedia Archive ID 31455

Overview

Model year	2004
Brand	GT
Model	Mach 1 Jr.
Bicycle type	BMX
Archive ID	31455
Original MSRP	$119.99
Colors	Blue
Sizes	Junior

Frameset

Frame construction	TIG-welded
Frame material	Hi-tensile steel
Fork	GT
Fork material	Hi-tensile steel, unicrown crown
Rear shock	N/A

Drivetrain

Component group	N/A
Shifters	N/A
Front derailleur	N/A
Rear derailleur	N/A
Crankset	Steel one-piece, 36 teeth
BB shell width	American
Rear cogs	1-speed, 16 teeth
Chain	KMC Z410, 1/2 x 1/8"
Pedals	BMX

Brakes

Brakes	Coaster brake rear

Cockpit & contact points

Headset	1" steel, threaded
Handlebar	GT BMX
Handlebar extensions	N/A
Stem	Aluminum
Saddle	GT JR. BMX
Seatpost	Chromoly, 22.2mm (7/8 inch) diameter

Wheels & tires

Hubs	Front: steel, nutted, Rear: steel, coaster brake
Rims	Steel, 28-hole
Spokes	Steel, 14ga. (2.0mm) straight gauge
Spoke nipples	Brass nipples
Front tire	16 x 2.125" BMX knobby
Wheel size	16" wheels

Geometry · Legacy reference

Top tube	393.7 mm
Head-tube angle	72°
Seat-tube angle	71°
Chainstay / rear center	299.7 mm

Manufacturer-published archive data. Confirm exact standards and dimensions before ordering parts or performing service. Generated by Velopedia on September 26, 2026.