Bicycle Archive · Specification report

2003 Diamondback RM JR

Velopedia Archive ID 39408

Overview

Model year	2003
Brand	Diamondback
Model	RM JR
Bicycle type	BMX
Archive ID	39408
Original MSRP	$279.99
Colors	Fast Black/Silver/Black
Sizes	Race

Frameset

Frame construction	TIG-welded
Frame material	7005 aluminum
Fork material	Chromoly, unicrown crown
Rear shock	N/A

Drivetrain

Component group	N/A
Shifters	N/A
Front derailleur	N/A
Rear derailleur	N/A
Crankset	1-piece 165mm, 42 teeth
Bottom bracket	YST BB-621
BB shell width	68mm English
Rear cogs	1-speed, 16 teeth
Chain	KMC Z610HX, 1/2 X 3/32"
Pedals	Aluminum platform

Brakes

Brakes	ProMax linear-pull rear brakes, Promax alloy rear levers

Cockpit & contact points

Headset	1" threadless FSA
Handlebar	Chromoly BMX
Handlebar extensions	N/A
Stem	Aluminum
Saddle	Diamondback Uni-style
Seatpost	Aluminum, 22.2mm (7/8 inch) diameter

Wheels & tires

Hubs	Aluminum
Rims	Alex AL-DA22, 36-hole
Spokes	Stainless steel, 14ga. (2.0mm) straight gauge
Spoke nipples	Brass nipples
Front tire	20 x 1 3/8" Comp III style
Wheel size	20" wheels

Geometry · Legacy reference

Top tube	539.8 mm
Head-tube angle	73°
Seat-tube angle	71°
Chainstay / rear center	386.1 mm
Wheelbase	868.7 mm
Fork offset / rake	20.3 mm

Manufacturer-published archive data. Confirm exact standards and dimensions before ordering parts or performing service. Generated by Velopedia on September 28, 2026.