Bicycle Archive · Specification report

2001 DirtMaster Big Bertha

Velopedia Archive ID 35136

Overview

Model year	2001
Brand	DirtMaster
Model	Big Bertha
Bicycle type	Freestyle/jumping
Archive ID	35136
Original MSRP	$569.00
Colors	Black, Green
Sizes	Pro
Weight	36 lb

Frameset

Frame construction	TIG-welded
Frame material	Chromoly
Fork	DirtMaster
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	3-piece aluminum/chromoly, 40 teeth
Bottom bracket	Three piece, sealed
BB shell width	American
Rear cogs	1-speed, 18 teeth
Chain	KMC Z410, 1/2 x 1/8"
Pedals	Radix

Brakes

Brakes	Dia-Compe 990 rear brakes, Dia-Compe Tech 99 rear levers

Cockpit & contact points

Headset	1 1/8" threadless Aheadset-Tank
Handlebar	DirtMaster Monkey Bar
Handlebar extensions	N/A
Stem	Radix
Saddle	Radix
Seatpost	Radix, 25.4mm diameter

Wheels & tires

Hubs	Radix
Rims	Alex aluminum, 48-hole
Spokes	Chung Nan stainless steel, 2.0mm straight gauge
Spoke nipples	Brass nipples
Front tire	24 x 1.95" Radix
Wheel size	24" wheels

Geometry · Legacy reference

Top tube	558.8 mm
Head-tube angle	74°
Seat-tube angle	69°
Chainstay / rear center	387.3 mm
Wheelbase	977.9 mm
Fork offset / rake	31.8 mm

Manufacturer-published archive data. Confirm exact standards and dimensions before ordering parts or performing service. Generated by Velopedia on September 30, 2026.