Polygon Syncline C5 29 (2023) - Text Review

Frame: The Syncline C5 uses Polygon’s ACX XC Performance carbon frame-set. It’s stiff yet claimed to be light, designed for cross country trails but generous with geometry so you can handle rough terrain. The head tube is tapered to reduce flex and improve front-end control. “Less flex for excellent front-end control with its tapered head tube design.”

Sizes & Fit: Comes in a range of sizes: 27.5″ Small & Medium; 29″ sizes from Medium up to X-Large. Geometry includes a head tube angle of ~67°, seat angle ~73°, reach increasing substantially as size goes up. Standover heights are generous. For Indian riders, someone ~170-180 cm tall may be comfortable starting with Medium 29″; for smaller riders, the 27.5″ Small or Medium. “We built you bikes that keep you rolling on cross country to technical tracks.”

Design: Clean lines, modern aesthetics. Two colour options (Black / Red-Black) per site. Subtle branding. It distinguishes itself from hardtails and heavier trail bikes by keeping weight down and a lean silhouette. The design is functional: the geometry says “fast climb, nimble on descents.” “Comes with a slack head tube angle and short chainstay, Syncline C takes you to have an excellent acceleration and the best performance on switchback turns.”

The Syncline C5 is outfitted with a Shimano SLX 12-speed group set. That includes SLX shifters (SL-M7100-R), SLX 1× crank (32T), cassette 11-51T, and SLX rear derailleur. This gives a wide gear range — steep climbs are manageable; flats and descents let you spin out. The 1× setup simplifies shifting and reduces things to worry about out on trail. “There’s more in less. The biggest advantage from a 1x drivetrain is it lets you focus on your ride, instead of constantly adjusting gears.” Front suspension via a Fox 32 Rhythm fork with 120 mm travel. Solid choice in this price segment. Helps absorb roots and bumps while keeping you composed. No rear shock (since this is a hardtail), which means less maintenance, lighter weight, but you’ll feel more jarring in very rocky, technical sections.
Performance wise, this bike gives efficient climbs, and when you’re ripping through trails it rewards you: quick acceleration, agile changes of direction thanks to relatively short chainstays. On tight switchbacks you’ll appreciate the design. In high-speed descents, the slackish head tube angle adds stability. “Excellent acceleration for an aggressive ride.”

Being a hardtail, inherent constraints exist: rougher trails will transmit more shock through the rear triangle. But Polygon addresses comfort where possible: carbon frame that balances stiffness with some compliance, a forgiving but stiff enough front suspension, and relatively wide tires (2.25″ Trail Boss) which help absorb hits. The geometry also reduces strain: seat tube angles in the 73° effective range help in climbing seated without sliding back. “Designed for riders built with adaptive carbon frame, Synline C gives you a better pedaling efficiency and riding feel.”
Handlebar is a wide Entity Xpert (740 mm) giving leverage and control; stem length, post drop etc seem well thought-out. The saddle (Entity Void) is average to good; for long rides you may want to change to something more suited to your anatomy. Seatpost (Entity Xpert 27.2×350 mm) is standard and gives enough adjustability.
On really rough terrain you’ll feel more fatigue over time than a full-suspension bike, obviously; but for many XC / mixed terrain rides this strikes a good balance between performance and comfort.

Brakes: Hydraulic disc brakes, Shimano MT400 (lever + caliper) front and rear, with rotor sizes: front 180mm, rear 160mm, centre-lock. Good stopping power and modulation. On steep descents or wet / muddy trail conditions the MT400 provides confidence; not top-tier XT/SLX brakes but solid for the price. “Accompanied with a responsive suspension that can be adjusted in various conditions and a resilient braking efficiency for any extreme use.”

Steering / Handling: Slack 67° head tube angle gives more stable front-end behaviour at speed and descending; short chainstay helps with nimbleness and quicker handling in twisty sections. Tapered head tube improves stiffness and precise steering input. The wide bar (740 mm) gives leverage. The flip side: on tight single tracks or in very slow technical manoeuvres, it demands more attention and may feel large for smaller riders. “Excellent acceleration for an aggressive ride … best performance on switchback turns.”

Steering / Handling: Slack 67° head tube angle gives more stable front-end behaviour at speed and descending; short chainstay helps with nimbleness and quicker handling in twisty sections. Tapered head tube improves stiffness and precise steering input. The wide bar (740 mm) gives leverage. The flip side: on tight single tracks or in very slow technical manoeuvres, it demands more attention and may feel large for smaller riders. “Excellent acceleration for an aggressive ride … best performance on switchback turns.”

Wheels & Tires: Double-wall alloy rims, 32 holes; tubeless-ready rims (30 mm internal width), which is good. Tires are WTB Trail Boss 2.25″ both front and rear (27.5 or 29 depending on frame size). This tyre provides good grip on mixed terrain, decent rolling speed. The option to run tubeless helps with reducing punctures and allowing lower pressures for better comfort. “Wheel set - ALLOY DOUBLE WALL … tyre 27.5×2.25 / 29×2.25 … rims 30 mm internal … tubeless ready.”
Saddle: The stock saddle is the Entity Void. It is decent and matches the finish and performance expectations at this price point, but is unlikely to be perfect for all riders. Some may find the shape or padding insufficient for extended rides or hard XC days. The seatpost gives decent range of adjustment.