Velopedia Bicycle Archive
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Compare published geometry, gearing and specifications for up to three bicycles.
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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 2006 GT Bump.
Gearing comparison
Lower gears help on climbs. Higher gears suit higher speeds.
RPM
RPM = pedal turns per minute.
Ratio2.79:1
Estimated speed at 90 RPMGear
Rear tire: 20×2.1.
Ratio2.77:1
Estimated speed at 90 RPMGear
Rear tire: 26×2.1.
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
2004 GT Bump
2006 GT Bump
Overview
Model Year
2004
2006
Brand
GT
GT
Model
Bump
Bump
Bicycle Type
Freestyle/jumping
BMX
Original MSRP
$249.99
$269.99
Colors
Red, Silver
RootBeer Brown, Pink
Sizes
One
20" wheel
Weight
—
—
Frameset
Frame Construction
TIG-welded
TIG-welded
Frame Material
Chromoly main triangle/hi-tensile steel rear stays
3-tube chromoly
Fork
GT
'05 GT dirt jump design
Fork Material
Chromoly, unicrown crown
Chromoly
Drivetrain
Component Group
—
BMX
Crankset
GT 3-piece chromoly, 39 teeth
GT Tubular Cr-Mo 3pc, 36 teeth
Bottom Bracket
—
Steel, ball type
BB Shell Width
American
—
Rear Cogs
1-speed, 14 teeth
1-speed, 13 teeth
Chain
KMC 410, 1/2 x 3/16"
KMC Z410
Pedals
GT Johnson design
'05 GT Dirt/Street platform design, aluminum body, cr-mo alxe
Brakes
Brakes
Tektro 907A U-brake rear brakes, Tektro 274A rear levers
Alloy side-pull caliper front/Tektro, 907AD, dual anchor bolts, forged aluminum U-brake rear brakes, Tektro, 274A, aluminum levers
Cockpit & Contact Points
Headset
1 1/8" threadless Victor VP-A74F
1 1/8" Tange Seiki FATTY 22, extra deep cup engagement
Handlebar
GT BMX
GT dirt/street bend, Cr-mo, 7" rise
Stem
GT Piston
GT Johnson III design, cold forged aluminum
Saddle
GT Jr Jump, 9mm rails
GT "Star 19" two piece design, 9mm rails
Seatpost
Steel micro-adjust
Aluminum double bolt micro adjust
Wheels & Tires
Hubs
Aluminum, 14mm axle
Front: '05 GT branded, aluminum body, sealed Mech. bearings, 3/8" Cr-Mo axle, 36 h, Rear: '05 GT branded, aluminum body, sealed Mech. bearins, 14mm Cr-Mo axle, 36 ho
Rims
Alex G22, 36-hole
Alex G22, aluminum, 36 hole, 30mm width, 36-hole
Spokes
Stainless steel, 14ga. (2.0mm) straight gauge
14ga. (2.0mm) Straight Gauge
Spoke Nipples
Brass nipples
Brass nipples
Front Tire
20 x 2.20" GT 1453
26 x 2.20" GT-1453
Rear Tire
20 x 2.10" GT LP-4
26 X 2.10" GT LP-IV
Wheel Size
20" wheels
26" wheels
Geometry · choose a size for each bicycle
Geometry size
—
Head-tube angle
74.5°
—
Seat-tube angle
71°
—
Chainstay / rear center
355.6 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.