Velopedia Bicycle Archive

2011 GT Bump

Original specifications: BMX Mix drivetrain · 20" wheels.

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At a glance

Archive #25117

Model year: 2011
Category: BMX
Colors: White, Matte Green
In this record: 24 specifications · archived image

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Identification clues

2011 archived details

Published colors: White, Matte Green
Frame: CroMo
Original equipment: BMX Mix

Clues, not proof of model year. Colors vary and components may have been replaced.

Original buildCroMo · BMX Mix · 20" wheels

Historical catalog variants

Archived sizes and colors

2 item records

Item-level catalog entries recovered from Velopedia’s original bicycle archive. They document how this model was listed historically; they do not identify the frame size associated with legacy reference geometry or indicate current availability.

Published colors

WhiteMatte Green

View 2 archived size/color combinations

Size	Color
—	White
—	Matte Green

Historical catalog evidence. Exact specifications and naming may vary by market, production run or manufacturer revision.

Frameset

Frame Construction	Steel
Frame Material	CroMo
Fork	Cromo
Fork Material	Steel

Drivetrain

Component Group	BMX Mix
Crankset	CroMO 3 piece, 25t teeth
Bottom Bracket	Sealed Bearing
Cassette	Cassette cog
Rear Cogs	9 teeth
Chain	KMC Z510
Pedals	GT Dirt/Street platform

Cockpit & Contact Points

Headset	1 1/8" integrated
Handlebar	GT Pro Steel
Handlebar Extensions	Not included
Stem	GT freestyle drop
Saddle	Pivotal Street Design
Seatpost	Pivotal, 25.4mm diameter

Wheels & Tires

Hubs	Front: GT Aluminum, Rear: GT Alloy
Rims	Alienation PBR, 32-hole/36-hole
Spokes	14ga. (2.0mm)
Spoke Nipples	Brass
Front Tire	20 x 2.125" Kenda K-Rad
Rear Tire	20 x 2.1" Kenda Ko-Rolla
Wheel Size	20" wheels

Gearing

Lower gears help on climbs. Higher gears suit higher speeds.

Pedal cadence

RPM

Speed units

RPM = pedal turns per minute.

Published build25T · 9T

Ratio2.78:1

Estimated speed At 90 RPM Gear15.0 mph

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.

Try other gearing

Try your current gearingChanged tires or gears? Calculate your setup.

Your changes apply to this calculation. The archived build stays unchanged.

Gears Drivetrain

Front teeth Smallest rear teeth Largest rear teeth

Use up to three front tooth counts, separated by /. For one rear sprocket, enter the same count twice.

Rear tire

Rear tire marking

Apply the marking on your rear tire or edit its dimensions below. Older or fractional inch sizes need the ISO marking (e.g. 37-590).

Rim diameter (BSD, mm) Tire width (mm)

For 32-622, width is 32 mm and rim diameter is 622 mm. Use the rear tire on mixed-wheel bikes. Leave both fields empty to compare ratios only.

Cadence (RPM) Speed units

Gear, dimension and cadence changes update results automatically.

Gearing comparison
Measure	Original	Your setup
Lowest ratio	—	—
Highest ratio	—	—
Total range	—	—
Lowest-gear speed	—	—
Highest-gear speed	—	—

Speeds are estimates. These calculations do not establish component compatibility or available tire clearance.

Parts & serviceability

Find replacement parts

Original specifications

Front tire · Original

20 x 2.125" Kenda K-Rad

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Rear tire · Original

20 x 2.1" Kenda Ko-Rolla

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Seatpost · Original

Pivotal

25.4mm diameter

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Parts and service referenceQuick reference before buying parts

Archived specifications for reference. Check the fitted parts before ordering.

Front tire: Front: 20 x 2.125" Kenda K-Rad, Rear: 20 x 2.1" Kenda Ko-Rolla
Drivetrain: BMX Mix
Seatpost diameter: 25.4 mm
Bottom bracket / shell: Sealed Bearing

Equipment inspection checks 9 checks based on 4 archived component groups Open equipment checksClose equipment checks

Checks selected from the archived equipment. Confirm what is fitted today. This is not a complete safety inspection; use the full inspection guide before test riding.

Full used-bike inspection guide →

Frame and fork

Inspect the frame and fork →

Archived: Frame: Steel · Fork: Cromo · Steel

Check paint damage, vent holes and accessible internal surfaces for corrosion. Look for dents, bent tubes and cracking around welded or brazed joints.
Inspect the fork crown, blades, dropouts and visible steerer area. Check that it is straight, securely installed and free of cracks or impact damage.

Drivetrain

Check drivetrain wear →

Archived: Group: BMX Mix · Crankset: CroMO 3 piece, 25t teeth · Bottom bracket: Sealed Bearing · Cassette: Cassette cog · Rear cogs: 9 teeth · Chain: KMC Z510

Shift through every available gear under light load. Hesitation, skipping or inconsistent indexing can reflect wear, damage, poor adjustment or mismatched replacement parts.
Measure chain wear with a compatible gauge and inspect chainring, cassette or freewheel teeth. A new chain does not rule out wear in the remaining drivetrain.
Turn the cranks slowly, feel for rough bearings and check for side-to-side play. Inspect crank arms, chainring bolts and pedal threads for looseness or damage.

Wheels and tires

Check wheels and tires →

Archived: Wheel size: 20" wheels · Rims: Alienation PBR, 32-hole/36-hole · Hubs: Front: GT Aluminum, Rear: GT Alloy · Front tire: Front: 20 x 2.125" Kenda K-Rad, Rear: 20 x 2.1" Kenda Ko-Rolla

Spin both wheels and watch for side-to-side and vertical movement. Check spoke tension, rim condition and hub play.
Inspect both tire casings for cuts, cracking, plugs, bulges or exposed threads and confirm the installed sizes are safe for the rims and available frame and fork clearance.

Controls and contact points

Archived: Headset: 1 1/8" integrated · Handlebar: GT Pro Steel · Stem: GT freestyle drop · Seatpost: Pivotal, 25.4mm diameter · Saddle: Pivotal Street Design · Pedals: GT Dirt/Street platform

Apply the front brake and rock the bike to check for headset play or notchiness. Inspect the stem, handlebar and clamp zones, then confirm every fastener and control is secure.
Check that the seatpost moves for adjustment and that the saddle, post and clamp hold securely without cracks, severe corrosion or damaged hardware.

Have you owned this model?Help document firsthand fit, ride and maintenance details that may no longer be available.

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Specifications are presented as a reference. Components may vary by market, size, production run, or later manufacturer revisions.

2011 GT Bump