The Sunday Primer 18 Inch Bike (2025) in red, viewed from the side against a white background, features black handlebars, seat, and tires along with pro-style frame geometry and Odyssey Springfield brakes for enhanced control.

The Sunday Primer 18 Inch Bike (2025), shown from the side on a white background, features a yellow frame with black handlebars, seat, and tires, plus pro-style BMX frame geometry.

A Sunday Primer 18 Inch Bike (2025) with a red pro-style frame, black handlebars, seat, and tires is parked on a paved surface.

The Sunday Primer 18 Inch Bike (2025), featuring a yellow frame, black handlebars, seat, and tires, is parked on pavement. It offers pro-style geometry for performance and Odyssey Springfield brakes for reliable stopping power.

Close-up of a black handlebar stem with "SUNDAY" engraved, mounted on the red frame of the Sunday Primer 18 Inch Bike (2025) featuring pro-style geometry.

Front view of the Sunday Primer 18 Inch Bike (2025) showing its branded handlebar, left brake lever, Odyssey Springfield brakes, and yellow pro-style frame geometry below.

Close-up of a black handlebar and stem on the yellow Sunday Primer 18 Inch Bike (2025) with pro-style BMX frame geometry, and a tire visible in the background.

Close-up of Odyssey Springfield brakes on the rear wheel of the Sunday Primer 18 Inch Bike (2025), showing the black brake caliper, brake cable, and part of the tire on a red BMX with pro-style frame geometry.

Close-up of a black handlebar grip and brake lever on the Sunday Primer 18 Inch Bike (2025) with pro-style frame geometry, photographed outdoors.

Close-up of the black crank and chainring on the Sunday Primer 18 Inch Bike (2025), attached to a red pro-style frame with the chain on the teeth.

Close-up view of the Sunday Primer 18 Inch Bike (2025) hub with "SUNDAY" branding, surrounded by black spokes and red components, emphasizing its pro-style frame geometry.

The Sunday Primer 18 Inch Bike (2025) is a black BMX featuring thick tires, pro-style frame geometry, straight handlebars, and a padded seat, pictured from the side against a white background.

The Sunday Primer 18 Inch Bike (2025) is a gold BMX with black handlebars, seat, pedals, and wheels. It features pro-style frame geometry and is shown on a white background.

The Sunday Primer 18 Inch Bike (2025) features a purple pro-style BMX frame, black handlebars, seat, and tires, shown side view against a white background.

Description

The Sunday Primer 18" is the ideal choice for riders who have outgrown a 16" but are not quite ready for a 20". A shorter chain stay, lighter wheels and size specific, pro style frame geometry make it the go to bike for serious BMXers in this size range.

It is packed with quality parts too. Odyssey Springfield U-brakes, a fully sealed 9T cassette hub, an FSA integrated headset and a KMC S1 chain give reliability you can count on, on Sunday Current 18 x 2.2" tyres front and rear.

Features

Bridges the 16" to 20" gap. Size specific, pro style geometry for riders who have outgrown a 16 inch but are not ready for a full size 20.
Shorter chain stay, lighter wheels. The bike is easier to throw around, which is what serious riders in this size range are after.
Fully sealed 9T cassette hub. A sealed 28H rear hub on a 14mm axle with a 9T driver, geared to suit the wheel size.
Odyssey Springfield U-brakes. Aftermarket brakes with an alloy U-brake compatible lever and Odyssey Quik Slic cable.
Sunday Freeze front load stem. A 48mm front load stem, 2 piece Sunday bars and Cornerstone grips give a cockpit that feels like the grown up bikes.

Specifications

Size: 18" wheels, 18.5" top tube
Frame: Sunday Primer, 18.5" top tube, integrated 1-1/8" head tube
Top tube: 18.5"
Fork: Sunday Primer, 18", 2 piece steerer tube with welded pre-load
Headset: FSA integrated 1-1/8" with FSA aluminium cap
Stem: Sunday Freeze front load, 48mm
Bars: Sunday, 2 piece
Grips: Sunday Cornerstone
Brakes: Odyssey Springfield U-brake with Odyssey Quik Slic cable
Brake lever: Aluminium, U-brake compatible
Cranks: 140mm, 3 piece, Cr-Mo
Bottom bracket: Sealed, mid, 19mm
Sprocket: Sunday Sabertooth v2, 25T, steel
Chain: KMC S1
Pedals: Wellgo platform, plastic
Front hub: Sunday, 28H, low flange, loose ball, 3/8" axle
Rear hub: Sunday, 28H, sealed, 14mm axle with 9T driver
Spokes: 14g steel, black
Rims: P-7X aluminium, 18", 28H
Tyres: Sunday Current, 18 x 2.2", front and rear
Seat: Sunday Badge, seat and post combo
Seat post: Integrated
Seat clamp: Sunday

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.

Sunday Primer 18 Inch Bike (2025)

Name: Sunday Primer 18 Inch Bike (2025)
Brand: Sunday
SKU: SUBK230-25-YEL
Price: 799.99 AUD
Availability: OutOfStock
Rating: 5.0 (1 reviews)

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

From

$799.99 AUD

$859.99 AUD

Or 4 payments of $199.99 AUD with

Colour - Gloss Yellow

Top Tube Length - 18.5

An 18 inch bike suits a rider of about 122 to 147cm, usually 7 to 11 years old, on an 18 to 18.5 inch top tube. It is the last step before a full size 20 inch.

Rider height	Wheel size	Top tube
60 to 91cm	12"	12 to 12.5"
81 to 106cm	14"	14 to 14.5"
96 to 122cm	16"	16 to 16.5"
122 to 147cm	18"	18 to 18.5"
147 to 157cm	20"	19.75 to 20.25"
157 to 168cm	20"	20 to 20.5"
168 to 175cm	20"	20.25 to 20.75"
175 to 183cm	20"	20.5 to 21"
183 to 190cm and up	20"	20.75 to 21.5"
160cm and up	22"	21 to 22.25"
160cm and up	24"	21.75 to 22"
160cm and up	26"	22 to 23"

Sizes overlap on purpose, so personal preference comes into it. If your rider is near 147cm and still growing, look at a 20 inch instead: it is the size they will keep riding.

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 an 18 and a 20? Take the 20. It is the size they will keep riding, and an 18 gets outgrown quickly.
They should be able to stand over the top tube with both feet flat on the ground.

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

Read the full buying guide

An 18 inch bike suits a rider of about 122 to 147cm, usually 7 to 11 years old, on an 18 to 18.5 inch top tube. It is the last step before a full size 20 inch.

Rider height	Wheel size	Top tube
60 to 91cm	12"	12 to 12.5"
81 to 106cm	14"	14 to 14.5"
96 to 122cm	16"	16 to 16.5"
122 to 147cm	18"	18 to 18.5"
147 to 157cm	20"	19.75 to 20.25"
157 to 168cm	20"	20 to 20.5"
168 to 175cm	20"	20.25 to 20.75"
175 to 183cm	20"	20.5 to 21"
183 to 190cm and up	20"	20.75 to 21.5"
160cm and up	22"	21 to 22.25"
160cm and up	24"	21.75 to 22"
160cm and up	26"	22 to 23"

Sizes overlap on purpose, so personal preference comes into it. If your rider is near 147cm and still growing, look at a 20 inch instead: it is the size they will keep riding.

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 an 18 and a 20? Take the 20. It is the size they will keep riding, and an 18 gets outgrown quickly.
They should be able to stand over the top tube with both feet flat on the ground.

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

Read the full buying guide

Discount 7%

Instead of ~~$859.99~~

$799.99 AUD

Price match request

Sunday Primer 18 Inch Bike (2025) - Gloss Yellow / 18.5