Close-up of a black Odyssey bicycle pedal attached to a crank arm, mounted on a Sunday Forecaster 20 Inch Bike (2022) / Alec Siemon with a 100% chromoly frame. The background is blurred pavement.

Close-up of a bicycle saddle with a brown fabric cover, mounted on a green Sunday Forecaster 20 Inch Bike (2022) / Alec Siemon frame, casting a shadow on the pavement in the background.

Close-up view of a green Sunday Forecaster 20 Inch Bike (2022) / Alec Siemon, showcasing the frame with white text declaring "100% Chromoly Frame," accompanied by an Odyssey Clutch v2 Freecoaster to deliver smooth, cutting-edge performance.

A Sunday Forecaster 20 Inch Bike (2022) / Alec Siemon model, featuring a green BMX frame with black tires and a brown seat, made with a 100% chromoly frame, is parked on a paved outdoor area with trees and vehicles in the background.

Description

The Forecaster rides, feels and looks like a pro-level bike, and this one is built on a 100% chromoly frame with an integrated 1-1/8" head tube and removable brake hardware. It is Alec Siemon's signature model, so it comes with Sunday Jake Seeley grips and a Sunday Duck Canvas Pivotal seat.

The rest of the build keeps up: an Odyssey Clutch v2 freecoaster with sealed hubs front and rear, Sunday Lightning rims, Odyssey Twisted PC Pro pedals, Odyssey Springfield brakes and 2.4" Path Pro OEM tyres. A dialled bike for every style of riding.

Features

100% chromoly frame. The Forecaster frame is full chromoly with an integrated 1-1/8" head tube, so it takes a beating and still feels pro-level.
Odyssey Clutch v2 freecoaster. Roll backwards without the cranks turning, which opens up fakies and switch riding without kicking your feet off the pedals.
Removable brake hardware. The Odyssey Springfield U-brake and lever come fitted, and the mounts strip off cleanly if you decide to ride brakeless.
Sealed hubs on Sunday Lightning rims. Sealed bearings front and rear keep the wheels spinning smoothly and need far less attention than loose ball hubs.
Alec Siemon signature touches. Sunday Jake Seeley grips, a Duck Canvas Pivotal seat, Odyssey Twisted PC Pro pedals and 2.4" Path Pro OEM tyres.

Specifications

Size: 20.75" top tube
Frame: Sunday Forecaster, 100% chromoly with integrated 1-1/8" head tube and removable brake hardware
Top tube: 20.75"
Chainstay: 13.2-13.5"
Head tube angle: 75.5°
Seat tube angle: 71°
Standover: 9"
Bottom bracket height: 11.7"
Fork: Sunday Forecaster, 20", 2-piece chromoly steerer tube with welded pre-load
Headset: FSA integrated conical, 1-1/8"
Stem: Sunday Freeze front load, 48mm
Bars: Sunday, 2-piece, 9" rise, 29" width, 12° backsweep, 3° upsweep
Grips: Sunday Jake Seeley
Brakes: Odyssey Springfield U-brake with Odyssey Quik Slic cable
Brake lever: Odyssey Springfield
Cranks: 170mm, 3-piece, chromoly
Bottom bracket: Sealed, mid, 19mm
Sprocket: Sunday Sabertooth v2, 25T, steel
Chain: KMC Z1 wide
Pedals: Odyssey Twisted PC Pro
Front hub: Sunday, 36H, low-flange, sealed, 3/8" female axle
Rear hub: Odyssey Clutch v2 freecoaster, 36H, 14mm female axle with 9T driver, RHD, non-drive side plastic guard
Rims: Sunday Lightning, 20", 36H
Tyres: Odyssey Path Pro OEM, 20 x 2.4"
Seat: Sunday Duck Canvas, Pivotal
Seat post: Sunday Pivotal
Seat clamp: Sunday
Weight: 12.1 kg (with brakes)

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 Forecaster 20 Inch Bike (2022) / Alec Siemon

Name: Sunday Forecaster 20 Inch Bike (2022) / Alec Siemon
Brand: Sunday
SKU: SUBK214-22-GRN
Price: 999.99 AUD
Availability: OutOfStock

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

$999.99 AUD

Or 4 payments of $249.99 AUD with

Recommended Rider Height:

168cm+

Colour - Alec Siemon

Top Tube Length - 20.75

A 20 inch bike is the standard adult BMX and suits riders from about 147cm up. At this wheel size the top tube is what changes the fit, so pick that by height.

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 you land in two bands, riding style breaks the tie: longer for flow, trails and transitions, shorter for technical street and park.

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.

Top tube is measured from the centre of the seat tube to the centre of the head tube, so it is not the same as the length of the tube you can see.

A 20 inch bike is the standard adult BMX and most riders end up there, so do not size a tall child down to a smaller wheel.
22, 24 and 26 inch bikes are adult bikes with a bigger wheel, not bigger frames for taller riders.
Size up for stability through trails and transitions. Size down if you want the bike quick and twitchy for spins and grinds.
Top tube is fixed, but stem length, fork offset and bar position all shift how roomy the bike feels once you are on it.

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

Read the full buying guide