- 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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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 2008 GT Bump.
- Data limitation
Only 2009 GT Bump has enough published drivetrain data for gearing calculations.
- Identity & price
2008 GT Bump had an original MSRP $120 lower than 2009 GT Bump.
Original MSRP is the published list price when new, not today’s used-bike value.
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.
Gearing unavailable for this size.
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
2008 GT Bump
Overview
Model Year
2009
2008
Brand
GT
GT
Model
Bump
Bump
Bicycle Type
BMX
BMX
Original MSRP
$399.99
$279.99
Colors
Light Green, Purple
Off White/Orange, Navy/White
Sizes
21.1" TT
One size fits all
Weight
—
—
Frameset
Frame Construction
TIG-welded
TIG-welded
Frame Material
Chromoly main triangle
GT cro-moly BMX dirt/street design
Fork
GT Dirt/Street
GT BMX design
Fork Material
Chromoly, unicrown crown
Chromoly, unicrown crown
Drivetrain
Component Group
BMX
BMX
Crankset
GT Tubular Cr-Mo 3pc., 33 teeth
GT Tubular Cr-Mo 3pc.
Bottom Bracket
Mid BB
Ball type with 8 spline Cr-Mo axle
Cassette
Cassette cog
—
Rear Cogs
1-speed, 12 teeth
1-speed, 12 teeth
Chain
KMC Z510
KMC Z410
Pedals
GT Dirt/Street platform
GT Dirt/Street platform
Brakes
Brakes
Tektro 907A U-brake rear brakes, Tektro 274A rear levers
N/A front/Tektro 907A rear brakes, Tektro 274A rear levers
Cockpit & Contact Points
Headset
1 1/8" Tange Seiki Fatty 22
1 1/8" Tange Seiki Fatty 22
Handlebar
GT dirt/street Cr-mo
GT dirt/street Cr-mo
Handlebar Extensions
Not included
Not included
Stem
GT FS design
GT FS design
Saddle
GT Slim
BMX mini street
Seatpost
Aluminum micro-adjust double bolt
Aluminum micro-adjust
Wheels & Tires
Hubs
Front: GT aluminum sealed, Rear: GT sealed cassette
Front: GT aluminum sealed, Rear: GT sealed cassette
Rims
Alienation PBR, 32-hole/36-hole
36-hole
Spokes
Stainless, 14ga. (2.0mm)
14ga. (2.0mm)
Spoke Nipples
Brass
Brass nipples
Front Tire
20 x 2.125" Kenda K-Rad
20" Kenda K-Rad
Rear Tire
20 x 2.10" Kenda Kiniption
20" Kenda Konxsion
Wheel Size
20" wheels
20" wheels
Historical specifications are presented as an archival reference. Components may have varied by market, size, or production run.