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 2008 GT Bump and 2009 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.
Gearing unavailable for this size.
Ratio2.75:1
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
2008 GT Bump
2009 GT Bump
Overview
Model Year
2008
2009
Brand
GT
GT
Model
Bump
Bump
Bicycle Type
BMX
BMX
Original MSRP
$279.99
$399.99
Colors
Off White/Orange, Navy/White
Light Green, Purple
Sizes
One size fits all
21.1" TT
Weight
—
—
Frameset
Frame Construction
TIG-welded
TIG-welded
Frame Material
GT cro-moly BMX dirt/street design
Chromoly main triangle
Fork
GT BMX design
GT Dirt/Street
Fork Material
Chromoly, unicrown crown
Chromoly, unicrown crown
Drivetrain
Component Group
BMX
BMX
Crankset
GT Tubular Cr-Mo 3pc.
GT Tubular Cr-Mo 3pc., 33 teeth
Bottom Bracket
Ball type with 8 spline Cr-Mo axle
Mid BB
Cassette
—
Cassette cog
Rear Cogs
1-speed, 12 teeth
1-speed, 12 teeth
Chain
KMC Z410
KMC Z510
Pedals
GT Dirt/Street platform
GT Dirt/Street platform
Brakes
Brakes
N/A front/Tektro 907A rear brakes, Tektro 274A rear levers
Tektro 907A U-brake 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
BMX mini street
GT Slim
Seatpost
Aluminum micro-adjust
Aluminum micro-adjust double bolt
Wheels & Tires
Hubs
Front: GT aluminum sealed, Rear: GT sealed cassette
Front: GT aluminum sealed, Rear: GT sealed cassette
Rims
36-hole
Alienation PBR, 32-hole/36-hole
Spokes
14ga. (2.0mm)
Stainless, 14ga. (2.0mm)
Spoke Nipples
Brass nipples
Brass
Front Tire
20" Kenda K-Rad
20 x 2.125" Kenda K-Rad
Rear Tire
20" Kenda Konxsion
20 x 2.10" Kenda Kiniption
Wheel Size
20" wheels
20" wheels
Historical specifications are presented as an archival reference. Components may have varied by market, size, or production run.