TAMBORA: Our Most Versatile Gravel Machine
TAMBORA A4
Features
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ACX Carbon Frame
Specifically tuned to balance lightweight performance with vibration damping, the ACX carbon frame is engineered to absorb chatter, allowing you to ride further with less fatigue.
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Flip Chip Geometry
Flip chips located at the rear dropouts and the base of the fork allowing you to extend the wheelbase, easily switching between snappy handling or more stable configurations.
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45c tire clearance
Increased tire clearance increases comfort and capability on mixed terrain.
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Frame and accessory mounts
With up to 14 universal mounts , there's plenty of scope to attach any bag or kit that suits your adventure.
Specification
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Frameset
FramesetForkSizeFrame ColorDecal Color
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Drivetrain
ShifterCrankCassetteRear DerailleurBBChain
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Cockpit
SaddleSeatpostHandlebarHandlestemHeadset
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Wheel & Tire
Wheel SetWheel SizeTireRimHubSpokes
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Brake
Brake LeverBrake CaliperRotor
Geometry & Size
| S | M | L | XL | |
|---|---|---|---|---|
| Height (cm) | 150-163 | 163-175 | 175-188 | 188-195 |
| Seat Tube Length (A) | 404 15.91 | 448 17.64 | 492 19.37 | 535 21.06 |
| Seat Tube Angle (B) | 74.75 2.94 | 74.26 2.92 | 73.76 2.9 | 73.26 2.88 |
| Effective Seat Tube Angle (C) | 74.75 2.94 | 74.26 2.92 | 73.76 2.9 | 73.26 2.88 |
| Head Tube Length (D) | 143 5.63 | 163 6.42 | 193 7.6 | 221 8.7 |
| Head Tube Angle (E) | 70.25 2.77 | 71.77 2.83 | 72.06 2.84 | 72.26 2.84 |
| Effective Top Tube (F) | 526 20.71 | 550 21.65 | 581 22.87 | 610 24.02 |
| Bb Height (G) | 265 10.43 | 265 10.43 | 265 10.43 | 265 10.43 |
| Bb Offset (H) | 79 3.11 | 79 3.11 | 79 3.11 | 79 3.11 |
| Chainstay Length (I) | 415 16.34 | 415 16.34 | 415 16.34 | 415 16.34 |
| Wheelbase (J) | 997 39.25 | 1003 39.49 | 1026 40.39 | 1048 41.26 |
| Frame Reach (K) | 371 14.61 | 383 15.08 | 400 15.75 | 415 16.34 |
| Frame Stack (L) | 566 22.28 | 591 23.27 | 621 24.45 | 648 25.51 |
| Standover Height (M) | 701 27.6 | 741 29.17 | 784 30.87 | 819 32.24 |
| S | M | L | XL | |
|---|---|---|---|---|
| Height (cm) | 150-163 | 163-175 | 175-188 | 188-195 |
| Seat Tube Length (A) | 404 15.91 | 448 17.64 | 492 19.37 | 535 21.06 |
| Seat Tube Angle (B) | 74.5 2.93 | 74 2.91 | 73.5 2.89 | 73 2.87 |
| Effective Seat Tube Angle (C) | 74.5 2.93 | 74 2.91 | 73.5 2.89 | 73 2.87 |
| Head Tube Length (D) | 143 5.63 | 163 6.42 | 193 7.6 | 221 8.7 |
| Head Tube Angle (E) | 70 2.76 | 71.5 2.81 | 71.8 2.83 | 72 2.83 |
| Effective Top Tube (F) | 526 20.71 | 551 21.69 | 581 22.87 | 611 24.06 |
| Bb Height (G) | 280 11.02 | 280 11.02 | 280 11.02 | 280 11.02 |
| Bb Offset (H) | 78 3.07 | 78 3.07 | 78 3.07 | 78 3.07 |
| Chainstay Length (I) | 425 16.73 | 425 16.73 | 425 16.73 | 425 16.73 |
| Wheelbase (J) | 1017 40.04 | 1022 40.24 | 1045 41.14 | 1067 42.01 |
| Frame Reach (K) | 369 14.53 | 381 15 | 397 15.63 | 412 16.22 |
| Frame Stack (L) | 568 22.36 | 593 23.35 | 622 24.49 | 650 25.59 |
| Standover Height (M) | 716 28.19 | 755 29.72 | 798 31.42 | 833 32.8 |
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FAQ
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Where are the mounts to hold gear? If I wanted to buy a bolted bag, what are the specifications? For full frame and half frame
There are 14 mounts on the Polygon Tambora series; 3 on the top tube, 7 on the down tube, 2 on the seat tube, and a pair of rear carrier mounts. We're using universal-size mounts, so there are no special specifications for the compatible bolted bag. You can freely choose the bolted bag that fits you best.
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What is the biggest chainring I can fit?
The maximum chainring of Tambora series is 48T.
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What are the biggest rotors I can fit?
The biggest rotors for the Tambora series are 160 mm.
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Can you fit mudguards and carriers?
Yes, only a rear mudguard and carrier can be fitted.
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How do you change the flip chip?
The Tambora has flip chips located at the rear dropouts and the base of the fork, allowing you to easily switch between gravel and all-road configurations. Watch the full video here.
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Can I fit a dropper post?
Yes! But it should be a gravel bike dropper post which commonly designed from 50mm to 125mm of travel.
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Is it possible to upgrade a road bike to a gravel bike?
This should not be possible because of the small tire clearance and its fixed aggressive geometry.
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How does the geometry of Tambora bikes differ from gravel bikes and other road bikes?
The gravel bike has a higher stack, slacker head angle, and longer wheelbase for stability.