- Frame
- Chromoly main triangle
- Brakes
- Tektro 907A U-brake rear brakes, Tektro 274A rear levers
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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 2009 GT Bump and 2011 GT Bump.
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: 20×2.1.
Ratio2.78:1
Estimated speed at 90 RPMGear
Rear tire: 20×2.1.
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
2009 GT Bump
2011 GT Bump
Overview
Model Year
2009
2011
Brand
GT
GT
Model
Bump
Bump
Bicycle Type
BMX
BMX
Original MSRP
$399.99
Not documented
Colors
Light Green, Purple
White, Matte Green
Sizes
21.1" TT
—
Weight
—
—
Frameset
Frame Construction
TIG-welded
Steel
Frame Material
Chromoly main triangle
CroMo
Fork
GT Dirt/Street
Cromo
Fork Material
Chromoly, unicrown crown
Steel
Drivetrain
Component Group
BMX
BMX Mix
Crankset
GT Tubular Cr-Mo 3pc., 33 teeth
CroMO 3 piece, 25t teeth
Bottom Bracket
Mid BB
Sealed Bearing
Cassette
Cassette cog
Cassette cog
Rear Cogs
1-speed, 12 teeth
9 teeth
Chain
KMC Z510
KMC Z510
Pedals
GT Dirt/Street platform
GT Dirt/Street platform
Brakes
Brakes
Tektro 907A U-brake rear brakes, Tektro 274A rear levers
—
Cockpit & Contact Points
Headset
1 1/8" Tange Seiki Fatty 22
1 1/8" integrated
Handlebar
GT dirt/street Cr-mo
GT Pro Steel
Handlebar Extensions
Not included
Not included
Stem
GT FS design
GT freestyle drop
Saddle
GT Slim
Pivotal Street Design
Seatpost
Aluminum micro-adjust double bolt
Pivotal, 25.4mm diameter
Wheels & Tires
Hubs
Front: GT aluminum sealed, Rear: GT sealed cassette
Front: GT Aluminum, Rear: GT Alloy
Rims
Alienation PBR, 32-hole/36-hole
Alienation PBR, 32-hole/36-hole
Spokes
Stainless, 14ga. (2.0mm)
14ga. (2.0mm)
Spoke Nipples
Brass
Brass
Front Tire
20 x 2.125" Kenda K-Rad
20 x 2.125" Kenda K-Rad
Rear Tire
20 x 2.10" Kenda Kiniption
20 x 2.1" Kenda Ko-Rolla
Wheel Size
20" wheels
20" wheels
Historical specifications are presented as an archival reference. Components may have varied by market, size, or production run.