
Velopedia Bicycle Archive
2025 Polygon Siskiu T27 EVO
Mountain bicycle from the Velopedia specification archive.
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What Velopedia knows
- Model year
- 2025
- Category
- Mountain
- Original MSRP
- $1,999.00
- Sizes
- XS
- Colors
- Cream
- Geometry
- 1 manufacturer size · Geometry context
- Record coverage
- 22 preserved details · 6 archived images · original MSRP · preserved geometry
- Archive ID
- 900001778
Frameset
| Frame Construction | ALX Trail 140mm Travel |
|---|---|
| Frame Material | Aluminum |
| Fork | RockShox Recon Silver-RL 150mm Travel |
| Rear Shock | RockShox Deluxe Select Plus, E2E: 210x55mm |
Drivetrain
| Shifters | Shimano Deore SL-M6100, 1X12-Speed Trigger |
|---|---|
| Rear Derailleur | Shimano Deore RD-M6100-SGS Direct Attach |
| Crankset | Shimano FC-M6120-1 Boost, 32T |
| Bottom Bracket | Shimano 2-Piece Crankset BSA Threaded |
| Cassette | Shimano Deore CS-M6100-12, 10-51T Microspline |
| Chain | KMC New X-12 |
| Pedals | Alloy Flat Pedal W/ Replaceable PIN & Reflector |
Brakes
| Brakes | Shimano Hydraulic Disc Brakes; Levers: Shimano BL-M4100; Rotors: Shimano SM-RT54, 180mm Center-Lock |
|---|
Cockpit & Contact Points
| Headset | FSA no.57E for Taper H/T, ZS 44/28.6 | ZS 56/40 |
|---|---|
| Handlebar | POLYGON EXPERT, W: 720mm, BB: 35mm, R/D: 30mm, B: 9 degree |
| Stem | POLYGON EXPERT, E: 35mm, BB: 35mm, R/D: 0 degree |
| Saddle | Fizik Terra Alpaca X5 |
| Seatpost | Dropper Post Xfusion Manic LC 100mm Travel, DXL: 30.9 X 314mm |
Wheels & Tires
| Hubs | F: Shimano HB-TC500-15-B Thru Axle 15x110mm 32H Center-Lock, R: Shimano FH-TC500-MS-B Thru Axle 12x148mm 32H Center-Lock for Microspline |
|---|---|
| Wheels | Polygon MT6 |
| Rims | Alloy Double Wall H: 18mm W: 29mm 584-27.5 32H for Tyre 584-54/76 TL Ready |
| Front Tire | Maxxis Dissector 27.5"X2.40" |
| Rear Tire | Maxxis Dissector 27.5"X2.40" |
Size-specific frame data
Geometry
Manufacturer-published geometry normalized for consistent archival comparison. Effective top tube and reach remain separate measurements because they describe different aspects of fit.
| Measurement | XS |
|---|---|
| Seat tube | 375 mm |
| Effective top tube | 559.2 mm |
| Head tube | 90 mm |
| Head-tube angle | 65° |
| Seat-tube angle | 76.5° |
| Actual seat-tube angle | 71° |
| Chainstay / rear center | 425 mm |
| Wheelbase | 1146.4 mm |
| Bottom-bracket drop | 20 mm |
| Bottom-bracket height | 335 mm |
| Reach | 420 mm |
| Stack | 579.87 mm |
| Standover height | 666 mm |
Geometry source: Polygon first-party metric geometry table ↗ Measurements can vary by configuration, wheel size, or flip-chip position where noted by the manufacturer.
Geometry tools
Analyze a published size
XS geometry
Archive context: The chainstay of 425 mm sits toward the shorter rear-center end. Its stack of 579.9 mm sits toward the lower end. Its reach of 420 mm sits somewhat longer than typical.
Compared with 56 distinct mountain geometries in the XS-equivalent size cohort from model years 2023–2027 in the Velopedia archive.Parts & serviceability
Find replacement parts
More qualified parts (6)
Searches use the archived manufacturer specification, not the components currently installed on a particular bicycle. Confirm the exact model, size and fit before ordering. As an Amazon Associate I earn from qualifying purchases. Velopedia may also earn from qualifying eBay purchases. Velopedia may also earn from qualifying retailer purchases. Commercial relationships do not influence Archive specifications or analysis.
Used-bike inspection
If you’re buying this bike used
Before any test ride: both brakes should stop the bike firmly and release cleanly; both wheels should run true and be securely attached; tires should have no casing damage; and the headset, handlebar, stem, cranks and pedals should have no looseness or play.
Follow the full used-bike inspection order →- FrameLook closely for dents and hairline cracks around welds, the head tube and bottom-bracket area. Cosmetic scratches matter less than a change in shape or a crack line.Inspect the frame and fork →
- BrakesBoth levers should feel firm and return cleanly. Check for fluid around the levers and calipers, inspect pad thickness and contamination, and look for worn or bent rotors.Inspect the brakes →
- SuspensionAsk when the fork and shock were last serviced. Check the stanchions for damage, look for oil at the seals, cycle both units through their travel and test the suspension pivots for play.Evaluate the suspension →
- DrivetrainShift through the full range under light load, measure chain wear and inspect the cassette or freewheel teeth. Skipping or hesitation can indicate wear, poor adjustment or mismatched parts.Check drivetrain wear →
- Wheels & tiresSpin both wheels and watch the rims for side-to-side or vertical movement. Check for dents, cracks, loose or uneven spokes and hub play, then inspect both tire casings for cuts, cracking or exposed threads.Check wheels and tires →
Bike-specific inspection checklist 22 checks based on 6 archived component groups Open checklistClose checklist
This checklist uses the archived equipment for this bike. It cannot confirm the condition, service history or later component changes of the example in front of you.
Identity and fit
Follow the full used-bike inspection order →Archived: 2025 Polygon Siskiu T27 EVO · Mountain · Published sizes: XS
Frame and fork
Inspect the frame and fork →Archived: Frame: ALX TRAIL 140mm TRAVEL · Fork: ROCKSHOX RECON SILVER-RL 150mm TRAVEL
Suspension
Evaluate the suspension →Archived: Fork: ROCKSHOX RECON SILVER-RL 150mm TRAVEL · Rear shock: ROCKSHOX DELUXE SELECT PLUS, E2E: 210x55mm
Drivetrain
Check drivetrain wear →Archived: Shifters: SHIMANO DEORE SL-M6100, 1x12-SPEED TRIGGER · Rear derailleur: SHIMANO DEORE RD-M6100-SGS DIRECT ATTACH · Crankset: SHIMANO FC-M6120-1 BOOST, 32T · Bottom bracket: SHIMANO 2-PIECE CRANKSET BSA THREADED · Cassette: SHIMANO DEORE CS-M6100-12, 10-51T MICROSPLINE · Chain: KMC NEW X-12
Brakes
Inspect the brakes →Archived: Brakes: SHIMANO HYDRAULIC DISC BRAKES; Levers: SHIMANO BL-M4100; Rotors: SHIMANO SM-RT54, 180mm CENTER-LOCK
Wheels and tires
Check wheels and tires →Archived: Wheels: POLYGON MT6 · Rims: ALLOY DOUBLE WALL H: 18mm W: 29mm 584-27.5 32H FOR TYRE 584-54/76 TL READY · Hubs: F: SHIMANO HB-TC500-15-B THRU AXLE 15x110mm 32H CENTER-LOCK, R: SHIMANO FH-TC500-MS-B THRU AXLE 12x148mm 32H CENTER-LOCK FOR MICROSPLINE · Front tire: MAXXIS DISSECTOR 27.5"x2.40" · Rear tire: MAXXIS DISSECTOR 27.5"x2.40"
Controls and contact points
Archived: Headset: FSA NO.57E FOR TAPER H/T, ZS 44/28.6 | ZS 56/40 · Handlebar: POLYGON EXPERT, W: 720mm, BB: 35mm, R/D: 30mm, B: 9 degree · Stem: POLYGON EXPERT, E: 35mm, BB: 35mm, R/D: 0 degree · Seatpost: DROPPER POST XFUSION MANIC LC 100mm TRAVEL, DxL: 30.9 x 314mm · Saddle: FIZIK TERRA ALPACA X5 · Pedals: ALLOY FLAT PEDAL W/ REPLACEABLE PIN & REFLECTOR
Before and during the test ride
Follow the full used-bike inspection order →Build relationships are limited to the archived manufacturer specifications. Confirm exact fit and standards before ordering parts or performing service.
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Specifications are presented as a reference. Components may vary by market, size, production run, or later manufacturer revisions.




