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Bike models › Mountain

Polygon Cascade 2: specs, upgrades and what fits

Polygon's cheapest 27.5" hardtail: aluminum frame, 100mm SR Suntour XCE28 coil fork, Shimano Tourney 3x7 with a 14-28 thread-on freewheel, Tektro MD-M280 mechanical disc brakes on 160mm rotors and QR wheels. Best for: Bike paths, parks and easy dirt trails.

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My take, from the specs

An entry 27.5-inch hardtail for bike paths, parks and easy dirt trails, with a 100 mm coil fork and Tektro mechanical discs on 160 mm rotors. The Shimano Tourney 3x7 runs a 14-28 thread-on freewheel, which limits low gears and upgrades. At about 15.4 kg it is heavy on climbs.

Sizes: S: 5′1″–5′5″ (155–165 cm) · M: 5′5″–5′9″ (165–175 cm)

Stock specs

TypeMountain
Year2026
Price when new$450
Sold atBikes Online US (bikesonline.com)
Wheels650b × 57 mm tires
Gears3×7 · 42/34/24T · 14–28T
BrakesTektro MD-M280
ForkSR Suntour XCE28 coil, 100mm, preload adjust, 9x100 QR, post mount 160mm
Rear derailleurShimano Tourney RD-TY300, 7-speed
ShifterShimano Tourney ST-EF41, 3x7 (integrated brake levers)
CrankWheeltop TCSH4-CFPG, 42/34/24T, 170mm
Bottom bracketGeneric Square taper, BSA 68mm
AxlesQuick release
Seatpost27.2 mm
Weight34.0 lb (15.4 kg)
SizesS, M
Stock colorsTeal Green

Upgrade limits

How far each part can go on this frame, and why. Measure your own bike to confirm the estimated ones.

PartLimitWhy
Widest tire (current wheel size)57 mmNo measurement yet. Estimate from owner reports and frame design. Your 21 mm internal rims suit roughly 31–55 mm tires.
TubelessNot recommendedTubeless needs a rim built to seal (bead hook + channel) and tubeless-ready tires.
Valve typeUnknownDecides which tubes and pump heads fit. Presta tubes fit Schrader rims with a grommet; not the other way.
Replacement wheelsQuick release · 100/135 mm · 6-bolt discAny wheel matching axle type, spacing and brake mount fits. Rear also needs the right freehub.
Biggest rear cog28T (now 28T)Set by the rear derailleur (Shimano Tourney RD-TY300): max low sprocket 28T, total capacity ?T. A hanger extender can add a few teeth (hit-or-miss on non-Shadow derailleurs); a new derailleur is the reliable way to get more.
Front gears3x (42/34/24T) · needs 32T capacityA 3x drivetrain needs a front derailleur and left shifter. Your rear derailleur must take up (biggest − smallest ring) + (biggest − smallest cog) = 32T. Going 1x drops the front derailleur: simpler and quieter, with a slightly smaller range.
Chainring sizeUnknown (now 42T)Estimated from similar frames. Measure the chainring-to-chainstay gap to confirm. Check whether your ring is bolted or riveted. Spindle length (? mm) sets chainline; a big change in ring size may need a different BB spindle.
Gear count upgradesFreewheel (≤8)Threaded freewheel: up to 7/8-speed freewheels only. More speeds needs a new rear wheel with a freehub.
Cranks & bottom bracketSquare taper · 68 mm shell · ? mm spindleAny square-taper crankset fits with the right spindle length. Upgrading to Hollowtech II needs a new BB (same threaded shell).
Pedal thread9/16" × 20Every adult multi-piece crank uses 9/16". One-piece kids/cruiser cranks use 1/2".
Brake padsShape unknownDisc pads only fit calipers with the matching shape.
Rotor size160/160 mm now · front up to 180 mm6-bolt rotors. Going bigger needs a caliper adapter: post mount +20 mm adapter. Most steel forks allow 180 mm; check the fork if a max rotor is printed on it.
Caliper upgradesLong-pull (MTB) mechanicalYour levers pull a lot of cable, so upgrade calipers must be long-pull (MTB) versions: TRP Spyke, Juin Tech M1, Avid BB7 MTB. Road calipers (TRP Spyre, BB7 Road) would feel mushy.
Stems & bars1-1/8 steerer · 31.8 mm bar clampAny stem for a 1-1/8 steerer with a 31.8 mm clamp fits. You can cut a bar narrower but not wider.
Drop-bar conversionPossible with modsNeeds road brake/shift levers (microSHIFT R8 makes 8-speed ones that pull Shimano 8-speed cable correctly), a drop bar, tape, and road-pull brake calipers because road levers pull less cable. Usually $250+.
Seatposts27.2 mm27.2 mm is the most common size: suspension posts and external-cable dropper posts are easy to find. Internal droppers need internal routing the frame does not have.
Racks, fenders, bottlesNo rack · No fender · 1 bottleThreaded eyelets at the dropouts and seat stays take a rack and fenders. Fork leg mounts take cargo cages.
Max load (rider + cargo)UnknownWheels are usually the weak point under heavy loads. Stay under this with rider plus luggage.

Best upgrades by area

Three options that fit the Polygon Cascade 2 as-is in each area, from budget to best. ★ marks the one most worth the money. How we pick. Typical US prices, checked October 2026. They change often: check the price at the store.

AreaGoodBetterBest
TiresWTB Horizon 650b x 47 TCS (pair)
$$$
WTB Byway 650b x 47 TCS (pair)
$$$ ★ Our pick
Teravail Washburn 650b x 47 Light & Supple (pair)
$$$
Grips & tapeBudget ergonomic lock-on grips
$
Ergon GP1 ergonomic grips
$$ ★ Our pick
Ergon GP5 ergonomic grips with built-in bar ends (S or L)
$$$
SaddleWTB Volt saddle
$$
Fizik Terra Argo X5 saddle (150 or 160 mm)
$$$
Ergon SR Allroad Core Comp saddle (men's or women's)
$$$ ★ Our pick
PedalsRace Face Chester composite flat pedals
$$ ★ Our pick
Crankbrothers Stamp 2 aluminum flat pedals (small or large)
$$$
OneUp Components Aluminum flat pedals
$$$
ChainKMC Z7 6/7-speed chain (116 links)
$
KMC X8 8-speed chain with Missing Link
$
KMC X8 EPT 6/7/8-speed anti-rust chain with Missing Link
$$ ★ Our pick
CassetteShimano Tourney MF-TZ500-7 7-speed freewheel 14–28
$
SunRace 7-speed freewheel 13-28 (MFM3S)
$ ★ Our pick
—
BrakesShimano Tourney BR-TX805 mechanical disc calipers, long pull, post mount (pair)
$$ ★ Our pick
Juin Tech M1 cable-hydraulic calipers, long pull (pair)
$$$
—
RotorsShimano SM-RT56 160 mm 6-bolt rotor (1 rotor)
$ ★ Our pick
Galfer Wave 160 mm 6-bolt rotor, 1.8 mm (1 rotor)
$$
Shimano SM-RT86 Ice-Tech 160 mm 6-bolt rotor (1 rotor)
$$
SeatpostSuspension seatpost 27.2 mm (budget)
$$ ★ Our pick
Redshift ShockStop suspension seatpost 27.2
$$$$
Cirrus Kinekt 2.1 Aluminum suspension seatpost 27.2 mm (LR or XR spring)
$$$$
Bar & stemRace Face Chester riser bar 31.8 x 740 mm, 25 mm rise
$$
Race Face Ride riser bar 31.8 x 710 mm, 25 mm rise
$$
SQlab 30X alloy riser bar 31.8 x 780 mm, 12° backsweep
$$$ ★ Our pick
LightsPlanet Bike Beamer 200 + Blinky Squared USB light set
$$ ★ Our pick
Cygolite Metro Plus 800 + Hotshot Pro 150 USB light set
$$$
Trek (Bontrager) Ion Pro RT + Flare RT light set
$$$

Upgrades that fit as-is

Brakes

Comfort

Control

Utility

Drivetrain

Tires

Gearing

Fits with small changes (21)

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Buying one used? Fair prices

Worked out from the price new ($450), age and condition, not live market data. If it needs tires, a chain or brakes, take off what fixing them would cost.

Condition1 year old3 years old5 years old
Like new$255–$335$205–$270$165–$220
Good$225–$295$180–$240$145–$195
Fair$185–$240$150–$195$120–$160
Needs work$140–$185$115–$150$90–$120

See what these really sold for on eBay · Other used bike prices

Geometry (size M)

Stack606°
Reach420 mm
Head angle68°
Seat angle75°
Chainstay440°
BB drop45 mm
Wheelbase1129 mm
Head tube120 mm
Seat tube430 mm
Standover734°

Compare with

Sources: Bikes Online US: Polygon Cascade 2 Mountain Bike [New] ($449.99, full spec, 34.06 lb S) · Polygon US: 2026 Cascade 2 specs + geometry