Radio Cobalt Pro Bike / Metallic Yellow / 20.5TT

Radio Cobalt Pro Bike BMX with a compact frame, straight handlebars, thick tires, and sealed front hubs shown from the side on a white background—perfect for entry-level racing.

The Radio Cobalt Pro Bike, shown in green with black tires, sealed front hubs, black handlebars, padded seat, and "RADIO" branding on the frame, is displayed from the side on a white background—perfect for entry-level BMX racing.

Description

The Cobalt line pairs proven race geometry with dialled components, so a new racer gets a good start out of the gate in their first days of racing. The line took off to the point that Radio added a Pro size, which opens one of the best entry level race bikes up to bigger riders.

Every Cobalt now runs fully sealed hubs and an integrated headset, which is a lot of bike for the spec, and the new paint and graphics make one easy to pick out on the track.

Features

Pro size, proven Cobalt geometry. A 20.75" top tube and 14" chainstays with dialled parts, so a full size rider gets the same start out of the gate.
Fully sealed hubs, integrated headset. Radio Cobalt CNC alloy hubs run fully sealed on 32H BX-32 double wall rims, and the FSA No.28 headset is sealed too.
175mm forged alloy cranks. A 44 x 16 drivetrain on a sealed BSA square taper bottom bracket, geared for a full size rider out of the gate.
Cr-Mo fork and bars. Cr-Mo legs with a 1-1/8" butted steerer and 30mm offset, under seamless 4130 bars at 7.5" rise and 28" width.
9.95kg on race rubber. Arisun XLR8 tyres, 1.95" up front and 1.75" out back, with a Promax alloy brake and lever on the rear.

Specifications

Size: 20" wheels
Frame: 6061-T6 alloy, forged dropouts with internal chain tensioner
Top tube: 20.75"
Chainstay: 14"
Head tube angle: 73°
Seat tube angle: 72°
Bottom bracket height: 11.5"
Fork: Cr-Mo, 1-1/8" butted steerer tube, Cr-Mo fork legs, 30mm offset
Headset: FSA No.28 integrated, sealed, 1-1/8"
Stem: Radio Cobalt top loader, 50mm extension, alloy
Bars: 4130 seamless Cr-Mo, 7.5" rise, 28" width, 11° backsweep, 3.5° upsweep
Grips: Radio, diamond knurling, closed end, flangeless, 130mm
Brakes: Promax TX-117 alloy, rear
Brake lever: Promax XL-378 alloy, rear
Cranks: Radio Cobalt 3pc, forged alloy, 175mm
Bottom bracket: Radio, BSA square taper, sealed
Chainring: Radio, 44T, alloy
Chain: KMC Z6, 1/2" x 3/32"
Pedals: Radio Cobalt Pro, alloy
Front hub: Radio Cobalt, CNC alloy, fully sealed, 32H, 3/8" Cr-Mo axle
Rear hub: Radio Cobalt, CNC alloy, fully sealed, 32H, flip flop, 3/8" Cr-Mo axle
Rear cog: ATA freewheel, 16T, 1/2" x 3/32", Cr-Mo
Rims: Radio BX-32, double wall, 32H, alloy front and rear
Tyres: Arisun XLR8, front 20" x 1.95", rear 20" x 1.75"
Seat: Radio Cobalt Pro combo seat
Seat post: Radio, 25.4mm, alloy
Seat clamp: Radio, forged alloy
Gearing: 44 x 16
Weight: 9.95kg

Assembly information

Your bike ships mostly assembled in the box. Finishing it takes most people 10 to 20 minutes with basic tools, and the video above walks through every step.

Fit the handlebars and line them up with the front wheel
Fit the front wheel, pedals and seat post
Check the brakes and tyre pressure before the first ride

Tools: Allen key set and a 15mm, 17mm or 19mm spanner for the pedals and axle nuts (bikes can vary between these three sizes). A socket is needed if installing pegs.

Rather have it done? Ask us about extra assembly before you order, or any local bike shop can finish the build for a small fee.

Radio Cobalt Pro Bike

Name: Radio Cobalt Pro Bike
Brand: Radio
SKU: RABK171-21-BLK
Price: 799.99 AUD
Availability: InStock
Rating: 5.0 (1 reviews)

Brand: Radio SKU: Click to copy the SKU and show the pick location

$799.99 AUD

Or 4 payments of $199.99 AUD with

Recommended Rider Height:

150-175cm

Colour - Black

Top Tube Length - 20.75

Race frames are sized by class, and the class you ride is set by rider height rather than age.

Size	Rider height	Top tube
Micro (18" wheels)	Under 120cm	16.25"
Mini (20" wheels)	110 to 140cm	17 to 18"
Junior	120 to 150cm	18.25 to 18.75"
Expert	130 to 170cm	19.5 to 19.75"
Expert XL	145 to 170cm	20 to 20.75"
Pro	150 to 175cm	20.25 to 20.75"
Pro XL	165 to 180cm	21 to 21.25"
Pro XXL	170 to 185cm and up	21.5 to 21.85"
Pro XXXL	175cm and up	22"
Pro XXXXL	180cm and up	22.5"
Cruiser (24" wheels)	175cm and up	21.5" and up

Heights overlap between classes on purpose. Where you land in two, a growing rider is usually better on the larger, and a rider who wants the bike to turn faster on the smaller. Some brands label the Pro size Pro L, with the same fit.

How to measure

Stand your rider against a wall in the shoes they ride in, heels flat, and mark the top of their head. Measure from the floor to the mark.

Between two sizes and still growing? Take the larger size.
Racing gates and wanting the bike to turn faster? Take the smaller size.
Top tube is the number that actually changes the fit, so compare it against the bike they ride now.

Not sure? Send us their height and we will tell you what we would put them on.

Read the full buying guide