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Polygon Syncline C5 - Carbon Mountain Bike
Polygon Syncline C5 - Carbon Mountain Bike
Polygon Syncline C5 - Carbon Mountain Bike
Polygon Syncline C5 - Carbon Mountain Bike
Polygon Syncline C5 - Carbon Mountain Bike
Polygon Syncline C5 - Carbon Mountain Bike
Polygon Syncline C5 - Carbon Mountain Bike
Polygon Syncline C5 - Carbon Mountain Bike
Polygon Syncline C5 - Carbon Mountain Bike
Polygon Syncline C5 - Carbon Mountain Bike
Polygon Syncline C5 - Carbon Mountain Bike
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Description

POLYGON QUALITY

So, you're new to mountain biking and want a high-value bike with progressive modern geometry perfect for local XC trails, racing or multi-day adventures? The C5 is your ticket to ride with a capable and lightweight carbon frame that will take you anywhere you want to go.

GEOMETRY

The C5s' sporty angles, tapered headtube, and stable chainstays make for better acceleration and steady handling. Ideal for fire trails, local single track and even the odd multi-day adventure. It features a 67° head tube and 73° seat tube angles, and 425-435mm chain stays for fast and snappy handling.

ACX CARBON

ACX carbon fibre is light, stiff, and strong. Polygon uses a blend of Toray T700 and High Modulus M series carbon, resulting in the maximization of strength and stiffness.

FOX FORK

Fox has created a super stiff chassis in a 120mm package and is now the benchmark for lightweight cross-country forks. It offers high performance, adjustability and improved damper performance.

SLX 12-SPEED

The Shimano SLX drivetrain is paired with an 11-51T cassette, giving you a +500% gear ratio to get up and down the mountain with ease.

Components

FRAMESET
FRAME
ACX XC Performance Carbon Fibre, Pressfit BB92, Internal Cable Route, Boost 12x148mm Rear Thru-Axle
SUSPENSION
FORK
Fox 32 Rhythm 120mm Travel, Rebound & Sweep Adjustment, Tapered, Boost Thru-Axle 15x110mm
DRIVETRAIN
REAR DERAILLEUR
Shimano SLX RD-M7100 Shadow Plus 12 Speed
SHIFTER
Shimano SLX SL-M7100
CRANK
Shimano SLX FC-M7100 Chainwheel 32T
CASSETTE
Sunrace MZ-800, 11-51T, 12-Speed
CHAIN
KMC X12
BRAKES
FRONT BRAKE
Shimano BR-MT401, 180mm Rotor
REAR BRAKE
Shimano BR-MT401, 160mm Rotor
WHEELS
REAR HUB
Novatec D462SB, 12x148mm 32H, Center Lock
RIM
Entity XL2 Disc, Double Wall Alloy Rims, 30mm Internal Width, Tubeless Tape Installed **
TYRE
WTB Trail Boss 27.5 x 2.25/29 x 2.25 *
CONTACT POINTS
HANDLEBAR
Entity Xpert Alloy 740mm
SADDLE
Entity Void, Steel Rail
SEATPOST
Entity Expert, Zero Offset, 27.2x350mm
STEM
Entity Xpert, Alloy 60mm
WEIGHT
BIKE WEIGHT
26lbs (Size L)

Geometry

  S M M L XL
Wheel Size 27.5" 27.5" 29" 29" 29"
Rider Height 5'2"-5'7" 5'5"-5'9" 5'6"-5'10" 5'10"-6'1" 6'1"-6'5"
(A) Stack 596 615 633 651 670
(B) Reach 410 430 430 450 470
(C) Head Tube Angle 67° 67° 67° 67° 67°
(D) Head Tube Length 100 120 100 120 140
(E) Seat Tube Angle 73° 73° 73° 73° 73°
Seat Tube Angle Effective 75° 75° 75° 75° 75°
(F) Seat Tube Length 380 420 420 460 500
(G) Top Tube Effective 569 594 597 621 649
(H) Bottom Bracket Height 308 308 307 307 307
(I) Bottom Bracket Offset 45 45 65 65 65
(J) Chainstay 425 425 435 435 435
(K) Wheel Base 1106 1134 1149 1176 1204
(L) Standover Height 690 729 730 763 779
Handle Bar Width 740 740 740 740 740
Fork Travel 120 120 120 120 120
Crank Length 170 170 170 175 175

* All lengths in mm

Assembly

Your bike needs minor assembly before riding; use the tools and videos included.

As a guide, it'll take 10-40min depending on whether you're an experienced bike assembler or have little to no mechanical experience.

Side Note: Your cables will stretch during the initial bed-in period and must be adjusted by an experienced mechanic around 150km of riding.

Step 1

Unboxing Your Bike

Step 2

Bike Fit Setup

Step 3

Tyre Pressure Setup

Step 4

Suspension Setup

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Customer Reviews
4.7 Based on 62 Reviews
5 ★
76% 
47
4 ★
19% 
12
3 ★
3% 
2
2 ★
0% 
0
1 ★
2% 
1
Customer Photos
2024 Polygon Syncline C5 - Carbon XC Mountain Bike - Customer Photo From Riley E.i
2024 Polygon Syncline C5 - Carbon XC Mountain Bike - Customer Photo From Riley E.i
2024 Polygon Syncline C5 - Carbon XC Mountain Bike - Size: L - 29" wheel - Customer Photo From Brian Gray i
2024 Polygon Syncline C5 - Carbon XC Mountain Bike [Wheel: 29][Size: M (height: 168-178cm)] - Customer Photo From LAURENCE OUTIMi
2023 Polygon Syncline C5 - Carbon XC Mountain Bike - Customer Photo From Phil Hennessyi
2021 Polygon Syncline C5 - Carbon XC Mountain Bike - Customer Photo From Mark Lakeni
2021 Polygon Syncline C5 - Carbon XC Mountain Bike - Customer Photo From Robert Garciai
2021 Polygon Syncline C5 - Carbon XC Mountain Bike - Customer Photo From Clive Mitchelli
2021 Polygon Syncline C5 - Carbon XC Mountain Bike - Customer Photo From Wili
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Filter Reviews:
FS
04/17/2025
Frank S.
United States United States

Super Fast Bike

This bike is a race machine. I've never been so fast on the trails. Lots of gears for the long climbs and the Fox fork is amazing. Very happy with this bike.

Polygon Syncline C5 - Carbon Mountain Bike
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AM
02/25/2025
Adrian M.
United States United States

Very pleased with my C5!

My Syncline C5 Review. I just completed an after work ride with my new Syncline C5. Having ridden only full suspension bikes since 1997 I was surprised how pleasant the ride was. The 2.25 WTB Trail Boss tires have a decent amount of volume and absorbed more trail chatter than I expected. The tires are wire bead and not tubeless compatible so today I just rolled with tubes. This is the first time I’ve run a mountain bike off road with tubes since 2010! Overall, the tires had good grip on the damp, hard pack, sandy trails here in Florida and seemed to roll pretty efficiently for having tubes in them. Having not ridden a hard tail in such a long time I was quite surprised at how nimble the bike was with what I would think would be a slack 67° head angle. My local trails are tight and winding and I had no issues getting around whatsoever. The drive train shifted surprisingly well for using a third-party cassette and chain. You could feel a little rumbly roughness through your feet when peddling though. This comes from a slightly rough finish on the cassette cogs where they interface with the chain rollers. When I wear out the cassette and chain, I’ll replace them with Shimano Deore units and the feel will become perfectly smooth. The Fox Rhythm 32 Fork was flawless from the very beginning. Rock Shox makes some nice forks, but I’m not a big fan of the steel stanchion Recon on the C3. The Fox fork is the main reason why I purchased a Syncline C5 as opposed to the less expensive C3 and it did not disappoint. I set it to 25% sag and it was amazingly responsive, making small trail chatter disappear and turning big hits into soft bumps you feel in your hands.  The saddle was quite comfortable, and the handlebar had a nice rise and sweep. The stem bar and seatpost are all house brand Entity components but they were solid and nicely made. I am just over 5’ 10”, I went with a size large and the fit is spot on out of the box. I was very happy that my bike came with Shimano 400 series hubs with a microspline freehub as opposed to the Novatec hubs noted on the website. The Shimano hubs are extremely well-made and durable. They only weigh a few more grams than the XT hubs with the main difference between them being the aluminum axles in the XT units versus the steel axles in these. Interestingly, all of the parts are interchangeable across Shimano‘s modern hubs. If I wanted to drop a few grams, I could install the front and rear aluminum XT axles. The Shimano 400 series brakes worked great. This bike comes with a 180 mm front disc, which was a nice touch. The rear disc is 160 mm. These brakes come with organic pads and organic only discs. Stopping power was quite good although I do miss the softer and more powerful lever feel of the Shimano SLX and XT servo wave brake levers. I do plan to upgrade a handful of things over time. I was a bike mechanic in college and have worked on my own bikes for the last 30 years. I will be getting a set of tubeless folding tires and converting the bike in the next few weeks. I like wearing gloves and love ultra thin grips, so I’ll be replacing the grips with my favorite, Amazon, thin, double lock on grips. I plan on re-lacing the hubs into some lighter rims with lighter spokes and alloy spoke nipples. As mentioned before, I will be getting a Deore 6100 series cassette and chain when what came with the bike wears out. Everything else on a bike is nice and the benefit of getting a namebrand or lighter stem and seat post wouldn’t be worth it. This is a cross country bike and I’m not going to be hucking it so I don’t need a dropper post. I got this bike for after work, fitness trail rides and kicking around town when I don’t want to ride a 55 pound E bike. I am super happy with my decision and think this bike is perfect for that purpose. I think it looks fantastic with the orange and black paint and all of the black accessories. Most importantly, it rides awesome!

Polygon Syncline C5 - Carbon Mountain Bike
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