With a sleek design, cutting-edge Bosch technology, and versatile performance features, the Polygon Tambora AE is a bold leap forward for gravel enthusiasts and urban explorers alike. This e-gravel bike promises to redefine the boundaries of adventure and utility.

Whether you’re tackling rugged gravel paths, scaling steep inclines, or looking for an elevated commuting experience, the Tambora AE offers the perfect blend of performance and innovation. Its lightweight ACX carbon frame and fork deliver unmatched comfort and responsiveness, while the powerful Bosch Performance Line Sprint motor, paired with the Compact Tube 400 battery, ensures long-lasting performance over any terrain.

As with all of our Tech Checks, this is not intended to be a long term review or endorsement of a product but is instead a chance for our viewers and readers to get a deeper look into some of the newest tech and products in electric bikes. We thank Polygon for the opportunity to create this feature and for getting you some valuable insight on this new offering.

The Tambora AE lineup includes two distinct models starting at $4099 for the AE-GRX and $4999 for the AE-GX, both are equipped with premium components to cater to diverse riding styles:

Tambora AE-GX

• SRAM Rival eTap AXS Shifters (Wireless)
• SRAM GX Eagle AXS 1×12 Drivetrain
• SRAM Rival Hydraulic Brakes with 160mm rotors

Tambora AE-GRX

• Shimano GRX 1×12 Drivetrain (Mechanical)
• Shimano GRX Hydraulic Brakes with 160mm rotors

Both models feature Novatec G24 carbon wheels and Schwalbe G-One Allround tires for optimal grip and stability. Fitted with the 40c Schwalbe’s the Tambora AE has clearance for up to 45c.

The bike’s Class 3 Bosch Performance Line Sprint motor delivers up to 28mph of pedal-assist, making it perfect for both European and North American riders. Between Bosch’s Performance line options, the SX is the lightest at 4.4lbs, while the Sprint prioritizes quick acceleration and high cadence, and the CX focuses on delivering the power for demanding terrain.

The Tambora AE uses the System controller integrated into the top tube and a Mini Remote located on the bars. As a Smart System device the Bosch system can be used with the Flow app.

The Tambora AE comes with a Compact Tube 400 battery integrated into the frame and a Powermore 250 range extender. Estimated range is about 48 miles on a full charge and up to 73 miles with the Powermore 250. Polygon has made a very easy to use quick release mechanism to release and replace the water bottle cage with the Powermore.

Contact points for the rider include a Fiziki Tera Argo saddle and a carbon seatpost. Out front there is a Vision SMR stem and FSA Energy Super Compact bar. 90mm stem and 400mm width bars on sizes Small/ Medium and a 100mm stem and 420mm bars on Large/ X-Large.

Polygon has designed the Tambora AE for adaptability. The FLIP CHIP system allows riders to customize their geometry for either a relaxed, ergonomic setup or a more aggressive, aerodynamic stance. Whether you prefer a mullet setup or traditional gravel configuration, the Tambora AE accommodates your style.

Key geometry specs include:

• Reach (Medium): 381mm
• Stack (Medium): 592mm
• Standover (Medium): 758mm
• Seat Tube Angle (Medium): 74°
• Head Tube Angle (Medium): 72°
• Chainstay Length: 432mm (all sizes)

The FLIP CHIP is located in the fork changing the position of the front axle. Changing the orientation of the chip and repositioning the brake caliper effectively will increase or decrease the head tube angle. Additionally, it will make changes to the wheelbase and BB height. Long mode for a more relaxed and ergonomic riding position and Short mode for a more aggressive aerodynamic position while riding.

Frame: ACX Carbon
Fork: ACX Carbon w/ FLIP CHIP

Drive Unit: Bosch Performance Line Sprint | Class 3
Battery: Bosch Compact Tube 400 | Powermore 250

Handlebar: FSA Energy Super Compact | 400mm (S-M), 420mm (L-XL)
Stem: Vision NS SMR-II ST | 90mm (S-M), 100mm (L-XL)

Shifters: SRAM Rival E-Tap AXS 12-speed
Brakes: SRAM Rival | 160mm
Derailleur: SRAM GX Eagle AXS 12-speed
Crankset: FSA Megatooth 44T
Cassette: SRAM XG 1275 GX Eagle 10-52T
Chain: SRAM GX Eagle

Saddle: FIZIK Tera Argo
Seatpost: 27.2 Carbon DXL | 300mm (S), 350mm (M-XL)
Wheels: Novatec G24 Disc Carbon | Tubeless Ready
Tires: Schwalbe G-ONE Allroad TLE Addix 700x40c

Frame: ACX Carbon
Fork: ACX Carbon w/ FLIP CHIP

Drive Unit: Bosch Performance Line Sprint | Class 3
Battery: Bosch Compact Tube 400 | Powermore 250

Handlebar: FSA Energy Super Compact | 400mm (S-M), 420mm (L-XL)
Stem: Vision NS SMR-II ST | 90mm (S-M), 100mm (L-XL)

Shifters: Shimano GRX BR-RX820 12-speed
Brakes: Shimano GRX | 160mm
Derailleur: Shimano GRX RD-RX822 12-speed
Crankset: FSA Megatooth 44T
Cassette: Shimano CS-M8100 XT 10-51T
Chain: Shimano CN-M6100

Saddle: FIZIK Tera Argo
Seatpost: 27.2 Carbon DXL | 300mm (S), 350mm (M-XL)
Wheels: Novatec G24 Disc Carbon | Tubeless Ready
Tires: Schwalbe G-ONE Allroad TLE Addix 700x40c

The Tambora AE does come with some limitations: there are no mounts on the frame for fenders and guards. Fortunately, in today’s world, there are still plenty of mounting solutions. You can still equip a frame bag for your essentials, maintaining its clean, minimalist design while readying it for adventure. The ACX Frame/ Fork have a max load capacity of 120kg to bring a lot of gear along the way.

Lightweight quick release fenders like the SKS Speedrocker or Ass Savers Win Wing 2 will fit easily without complications. If you’re looking to maximize your storage, a handlebar bag or seat pack will be the ideal way to optimize your load.

While tackling our first few shakedown rides, we were beyond pleased with the comfort and power of the Tambora AE. Coming in at $4999, the SRAM AXS driven AE-GX makes for quick and reliable shifting. After over 50 miles of both tarmac and gravel roads, feeling comfortable and confident came quickly after a basic setup of saddle height, angle, and adjusting the bars a bit. Getting things under way the ACX Carbon frame and fork feels firm and responsive thanks to the stiff and short 432mm chainstays, while being supple and smooth due to the dropped seat stays. The ideal combination for long days in the saddle on rough terrain.

The power of the Bosch Performance Line Sprint took a bit to get used to plan out the proper way to attack climbs and maintain high speeds over long paved stretches. I found it favoring higher cadence to keep the speed and power on demand. The wide spread of the GX cassette is what really makes the Tambora come alive. From an 10 tooth high gear out on the road to a 52 tooth low gear to creep your way up the steepest grades. The mullet Rival/GX drivetrain with the Bosch Performance Line Sprint proves to be a great balance of power and speed.

Taking a look back at our shakedown rides and checking our numbers, I found that maintaining a 20mph average in ECO and Tour+ was comfortable and will be what many riders should expect. All the same, real world numbers on relatively flat terrain in 30°- 40°F temps with minimal wind led the Tambora AE to consistently use about 65% battery for a 25 mile road ride.

Whether you’re charting new trails or upgrading your commute, the Polygon Tambora AE combines innovation, performance, and style. Available in AE-GX and AE-GRX models, this gravel e-bike is ready to take you further, faster, and smoother than ever before.

Price: AE-GX $4999| AE-GRX $4099
Sizes: S, M, L, XL
Weight: ~32 lbs (size large w/ pedals)
Website: polygonbikes.com