Polygon Tambora A4 All-Road Gravel Bike
The Polygon Tambora A4 is a versatile all-road and gravel bike designed for speed, stability and adventure. Its adjustable geometry allows it to provide responsive handling on smoother roads or greater stability when riding over gravel and rough terrain.
A durable ALX alloy frame is paired with a lightweight carbon fork, Shimano GRX 2x11-speed drivetrain and Shimano GRX hydraulic disc brakes. With clearance for tyres up to 45mm and 14 mounting points, the Tambora A4 is ready for daily riding, gravel exploration and multi-day bikepacking.
Two Bikes in One
Flip chips at the rear dropouts and the base of the fork allow the rider to switch between all-road and gravel geometry. Changing the position adjusts the wheelbase and handling characteristics of the bike.
The all-road position creates a shorter wheelbase for quicker and more responsive handling. The gravel position extends the wheelbase to improve stability and control on loose or uneven terrain.
ALX Alloy Frame and Carbon Fork
The ALX alloy frame provides durability, efficient power transfer and dependable performance. Its balanced geometry gives the Tambora A4 a fast road-bike feel while retaining the stability required for gravel riding.
The carbon rigid fork helps reduce weight and absorb vibration from broken roads and gravel tracks. It also provides accurate steering and confident control.
Shimano GRX 2x11-Speed Drivetrain
The Shimano GRX 2x11-speed drivetrain provides a wide selection of gears for fast road riding, steep climbs and long-distance adventures. Gravel-specific Shimano GRX controls are designed to provide secure and comfortable operation over rough surfaces.
A 48/31T crankset is paired with an 11-34T Shimano cassette. The two-chainring setup provides smaller steps between gears while retaining a broad range for mixed terrain.
Shimano GRX Hydraulic Disc Brakes
Shimano GRX hydraulic disc brakes deliver strong and controlled stopping power in dry, wet and dusty conditions. Shimano RT-CL700 160mm rotors provide dependable braking during fast descents and loaded bikepacking trips.
Tyre Clearance up to 45mm
The Tambora frame provides clearance for tyres up to approximately 45mm wide. This allows riders to use faster tyres for all-road riding or wider tyres for increased grip and comfort on gravel.
The bike is supplied with Maxxis Pursuer 700x32C tyres. Its alloy double-wall rims are tubeless ready and can be converted using compatible tubeless tyres, suitable rim tape, valves and sealant.
Ready for Bikepacking
The Tambora platform includes 14 mounting points across the frame and fork. These can be used for compatible bottle cages, luggage, racks and bikepacking accessories.
This extensive carrying capacity makes the Tambora A4 suitable for commuting, long-distance touring and self-supported cycling adventures.
Key Features
- Durable ALX alloy frame
- Lightweight carbon rigid fork
- Adjustable all-road and gravel geometry
- Flip chips at the fork and rear dropouts
- Shimano GRX 2x11-speed drivetrain
- 48/31T double-chainring crankset
- Wide-range Shimano 11-34T cassette
- Shimano GRX hydraulic disc brakes
- 160mm Shimano Center Lock rotors
- Maxxis Pursuer 700x32C tyres
- Clearance for tyres up to approximately 45mm
- Tubeless-ready alloy rims
- 12mm front and rear thru axles
- 14 mounting points for luggage and accessories
- Available in four frame sizes
Specification
- Frame: ALX XC Trail alloy frame
- Fork: Carbon rigid fork
- Shifters: Shimano GRX ST-RX600, 2x11-speed
- Rear derailleur: Shimano GRX RD-RX810
- Crankset: Prowheel RPZ C701X TT, 48/31T
- Cassette: Shimano CS-HG700, 11-34T
- Bottom bracket: BSA threaded, 68mm
- Chain: KMC X11
- Brake levers: Shimano GRX ST-RX600
- Brake calipers: Shimano GRX hydraulic disc
- Brake rotors: Shimano RT-CL700 160mm
- Wheel size: 700C
- Rims: Alloy double-wall, 32-hole, tubeless ready
- Front hub: Novatec D791SB, 12x100mm thru axle
- Rear hub: Novatec D792SB, 12x142mm thru axle
- Tyres: Maxxis Pursuer 700x32C
- Handlebar: Polygon Expert alloy
- Stem: Polygon Expert alloy
- Seatpost: Polygon Expert, 27.2x400mm
- Saddle: Linc Flux 2
- Headset: Token TK156SP-36 with sealed bearings
- Colour: Charcoal and Blue with silver decals
Handlebar Width
- Small and Medium: 420mm
- Large and Extra Large: 440mm
Stem Length
- Small and Medium: 90mm
- Large and Extra Large: 100mm
Recommended Rider Height
- Small: 150-163cm
- Medium: 163-175cm
- Large: 175-188cm
- Extra Large: 188-195cm
Frequently Asked Questions
What type of bike is the Polygon Tambora A4?
The Polygon Tambora A4 is an adjustable all-road and gravel bike designed for road riding, gravel tracks, commuting, touring and bikepacking.
Does the Tambora A4 have adjustable geometry?
Yes. Flip chips at the fork and rear dropouts allow the rider to switch between responsive all-road geometry and more stable gravel geometry.
How do the two geometry settings differ?
The all-road position shortens the wheelbase for quicker handling. The gravel position lengthens the wheelbase to improve stability and control on rough terrain.
Does the Polygon Tambora A4 have a carbon frame?
No. It has a durable ALX alloy frame combined with a lightweight carbon fork.
What drivetrain does the Tambora A4 use?
It uses a Shimano GRX 2x11-speed drivetrain with a 48/31T crankset and an 11-34T cassette.
Why does the Tambora A4 use two front chainrings?
The 2x drivetrain provides a wide gear range with smaller steps between gears. This is useful for maintaining a comfortable pedalling speed on roads, climbs and changing terrain.
Does the Tambora A4 have hydraulic disc brakes?
Yes. It is equipped with Shimano GRX hydraulic disc brakes and 160mm Shimano rotors.
What is the maximum tyre clearance?
The Polygon Tambora platform provides clearance for tyres up to approximately 45mm wide, depending on the tyre, rim and riding conditions.
Are the wheels tubeless ready?
Yes. The alloy rims are tubeless ready. Compatible tubeless tyres, suitable rim tape, valves and sealant are required for conversion.
Is the Polygon Tambora A4 suitable for bikepacking?
Yes. It has 14 mounting points for compatible bottles, bags, racks and bikepacking accessories.
Can I fit a dropper seatpost?
Yes. The Tambora frame can accept a compatible 27.2mm gravel dropper seatpost, normally with approximately 50mm to 125mm of travel.
Component specifications may be changed by the manufacturer without prior notice.
