2021 Polygon Siskiu D5 – 27.5inch Dual Suspension Mountain Bike

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Light & durable Hydroformed 6061 Aluminum frame features tapered head tube, internal cable routing, optimized anti-squat kinematic and progressive suspension ratio.


Using the most of the modern features, Siskiu D models utilize slack head tube and steep seat tube angle to ensure that the bike handles perfectly and travels effortessly up and down the mountain.


Both units feature 120mm of travel and hydraulic lockout. The firmness can be customized by preload adjuster on fork and by air pressure on rear shock.


Provides smooth and precise shifting for 2×9-speed mountain bike drivetrains. The RapidFire Plus lever gives riders the ability to downshift three gears in one stroke.


Proven, bombproof design with reliable braking performance.


Predictable, fast, grip in every situation.



In a world where bike prices seem to continue to go one direction, the Polygon Siskiu D5 is a breath of fresh air offering a properly capable full suspension mountain bike at a price that won’t break the bank. Utilizing the same platform technology as the higher end Siskiu bikes, the new D5 delivers outstanding performance and reliability and will have you grinning from ear to ear on your next adventure.

The D5 is built around a lightweight, ALX aluminum frame that boasts a modern geometry for the modern rider. The bike now has a slacker head tube angle, longer reach, lower BB and shorter chain-stay to boost your performance in climbing or descending, no matter the distance, technicality or gradient. Polygon has also revised kinematics on the Siskiu D. The anti-squat has been optimized and the suspension is more progressive. It has 120mm of travel in the rear, and the frame now also comes with room for a water bottle mount.

A Suntour XCM HLO, fork dampens up the front end of the bike with 120mm of hydraulically damped travel. A Suntour Raidon rear air shock provides the suspension duties out the back ‘ both the front fork and rear shock feature a lockout, this enables you to improve performance while climbing or to improve efficiency on the road.

Rapid-fire Shimano Alivio shifting components promise smooth, reliable, and responsive action even in situations of extreme torque such as steep hills. With the 18 Speed Shimano Alivio-M3000 series drivetrain, you get a huge range of gearing for any riding scenario from high speed descents to easily climbing the steepest of hills. The new super low profile Shimano Shadow technology keeps the Alivio M3000 derailleur safe from trail obstacles while providing a sleek finish on the gear set.

For stopping power, hydraulic disc brakes have been provided for by Shimano, who are undoubtedly the best name in brakes. The front rotor has been oversized to 180mm in the D5 and together with the Shimano levers and calipers, provide confidence inspired braking in all weather conditions. The bike rolls on a set of alloy double wall rims wrapped in 27.5″ x 2.25″ Entity Spiderbait tires.

A host of Entity alloy components such as handlebars, seatpost and stem, all work together to keep the weight down, the bike powerful, and the handling precise.


Model Comparison Chart

  2021 Siskiu D5 2021 Siskiu D7
Frame ALX XC Trail 6061 Aluminum Frame, 120mm Travel, Internal Routed Gear Cables, Taper Headtube, QR Boost, Internal Routed Dropper Post Compatible ALX XC Trail 6061 Aluminum Frame, 120mm Travel, Internal Routed Gear & Dropper Cables, Tapered Headtube, 73mm Threaded Boost BB, 148x12mm Boost Thru- Axle
Fork SR Suntour XCM HLO, 120mm Travel, Preload Adjuster, Hydraulic Lockout Rockshox Recon RL, Solo Air, 120mm Travel (27.5″ & 29″), Rebound & Compression Adjuster, 46mm (27.5″) & 51mm (29″) Offset, Maxle Stealth Axle 100x15mm
Rear Shock SR Suntour Raidon- LO AIR, E2E: 190X51mm, Hardware: M8x22mm Rockshox Deluxe Select Plus, DebonAir, Rebound & Compression Adjuster, E2E 190x45mm, M8x25mm Hardware
Headset Polygon Internal Caged Bearings, ZS 44/28.6 | ZS 56/40 Threadless Zero Stack Headset, ZS 44/28.6 | ZS 56/40
Crankset Shimano Altus FC-MT2102 36x22T Boost, 170mm Shimano Deore FC-M5100 Boost 32T, Crank Length: 170mm (S, M) / 175mm (L, XL)
Drivetrain Shimano Alivio M3000 2X9 Speed Shimano Deore M5100 1X11 Speed Wide-range
Bottom Bracket Shimano BSA Threaded, 73mm BSA Threaded 73mm
Brakes Shimano BR-M201 Hydraulic Disc, Rotor F: 180mm R: 160mm Shimano BR-M201 Hydraulic, Rotor F/R: 180/160mm
Tire Entity Spiderbait 27.5×2.25″ Schwalbe Nobby Nic Performance 27.5/29×2.25″, Tubeless ready*
Rim Doublewall Alloy 24mm Internal Width Entity X15 Doublewall Disc 32H, 30mm Internal Width, Tubeless Ready*
Spokes Stainless Steel Spokes Stainless Steel Spokes, *tubeless tape and valve sold separately
Price $1,099 $1,699


How the Bike is Delivered to You

Your bike will arrive in a custom Bikes Online bike guard box as described in the video below.

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