- Frame
- Chromoly
- Brakes
- DiaTech 996 U-Brake rear brakes, Dia-Compe MX-101 rear levers
Velopedia Bicycle Archive
Compare Bicycles
Compare published geometry, gearing and specifications for up to three bicycles.
Edit comparison
Add a bicycle
Search the Archive without leaving this comparison.
1 of 2 bicycles
At a glance
Key differences
Supported differences are shown below. Data limitations are labeled separately.
- Data limitation
No geometry is recorded for 2001 GT Thumper.
Gearing comparison
Lower gears help on climbs. Higher gears suit higher speeds.
RPM
RPM = pedal turns per minute.
Ratio2.75:1
Estimated speed at 90 RPMGear
Rear tire: 20×1.75.
Ratio2.75:1
Estimated speed at 90 RPMGear
Uses front tire 20×2.1; rear size isn’t listed.
How it works
Ratio = front teeth ÷ rear teeth. Hub gears also include the hub’s internal ratio. A 400% range means the highest ratio is four times the lowest.
Speeds are estimates from tire size and pedal cadence. Actual speeds vary.
Complete specification tableShows different published values and gaps where a bicycle lacks data. Different wording reflects source language, not necessarily different components. Swipe for more columns.
Specification
2000 GT Thumper
2001 GT Thumper
Overview
Model Year
2000
2001
Brand
GT
GT
Model
Thumper
Thumper
Bicycle Type
Freestyle/jumping
Freestyle/jumping
Original MSRP
$478.00
$549.99
Colors
Gangreen, Propane
Martian Green, Starlight Blue
Sizes
—
Pro
Weight
—
—
Frameset
Frame Construction
TIG-welded
TIG-welded
Frame Material
Chromoly
Chromoly
Fork
GT
GT
Fork Material
Chromoly, unicrown crown
Chromoly, unicrown crown
Drivetrain
Crankset
GT 3-piece chromoly, 44 teeth
GT 3-piece chromoly, 44 teeth
Bottom Bracket
Sealed cartridge
Sealed cartridge
Rear Cogs
1-speed, 16 teeth
1-speed, 16 teeth
Chain
KMC, 1/2 x 1/8"
KMC, 1/2 x 1/8"
Pedals
GT aluminum platform
GT aluminum platform
Brakes
Brakes
DiaTech 996 U-Brake rear brakes, Dia-Compe MX-101 rear levers
Tektro FX-20 U brake rear brakes, Tektro 270-AX rear levers
Cockpit & Contact Points
Headset
1 1/8" threadless Aheadset SB-1 w/SST Oryg detangler
1 1/8" threadless Tange Seiki STE
Handlebar
GT Freestyle
GT F.U.B.a.R.
Handlebar Extensions
Not included
Not included
Stem
GT Johnson
GT Johnson
Saddle
GT
GT
Seatpost
GT aluminum micro-adjust
GT aluminum micro-adjust
Wheels & Tires
Hubs
GT Mohawk
GT Mohawk
Rims
Weinmann ZAC-X, 48-hole
Alex AL-MX22, 48-hole
Spokes
2.0mm
14g
Spoke Nipples
Brass nipples
Brass nipples
Front Tire
20 x 2.125" Powerlite Retro Tread
20 X 2.10" GT LP-III
Rear Tire
20 x 1.75" Powerlite Retro Tread
—
Wheel Size
20" wheels
20" wheels
Geometry · choose a size for each bicycle
Geometry size
—
Head-tube angle
73.5°
—
Seat-tube angle
70°
—
Chainstay / rear center
381 mm
—
Wheelbase
967.5 mm
—
Historical specifications are presented as an archival reference. Components may have varied by market, size, or production run. Legacy reference geometry is model-level historical data whose corresponding frame size is not identified; compare those dimensions as reference values rather than size-normalized fit data.