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Bike models › Mountain

Haro Flightline Two 29: specs, upgrades and what fits

Haro's long-running entry 29er hardtail, redesigned with internal cable routing and a tapered head tube: Zoom 80mm fork, Shimano Altus 1x8 with a 12-32 cassette, JAK-7 mechanical disc brakes on 160mm rotors and quick-release wheels. Best for: Bike paths, dirt roads and easy singletrack.

Put this bike in your garageSee it in 3D

My take, from the specs

A fair entry 29er for bike paths, dirt roads and easy singletrack, and the Altus 1x8 drivetrain is simple to use. The JAK-7 mechanical discs need regular pad adjustment, and the 80mm Zoom fork is basic, so keep it to mellow trails. The 32x32 low gear can feel tall on steep climbs, though the frame is dropper-ready with internal routing for later upgrades.

Sizes: S: 5′2″–5′7″ (158–171 cm) · M: 5′6″–5′11″ (168–180 cm) · L: 5′10″–6′2″ (178–189 cm) · XL: 6′1″–6′6″ (186–199 cm)

Stock specs

TypeMountain
Year2025
Price when new$650
Sold atHaro dealers / harobikes.com
Wheels700c × 53 mm tires
Gears1×8 · 32T · 12–32T
BrakesJAK JAK-7 mechanical disc
ForkZoom 80mm suspension fork
Rear derailleurShimano Altus 8-speed
ShifterShimano Altus 8-speed Rapidfire with optical window
CrankProwheel 3-piece square-taper alloy arms
Bottom bracketGeneric Sealed cartridge, 73mm
AxlesQuick release
Seatpost31.6 mm
SizesS, M, L, XL
Stock colorsGloss Black, Matte 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)53 mmUnknown until measured. Your 25 mm internal rims suit roughly 37–65 mm tires.
Other wheel sizes650b up to ~60 mmDisc brakes don't care where the rim sits, so a 650b wheel with a fatter tire fits. A 650b × 47 is about the outer size of a 700 × 28, so the bottom bracket sits about 12 mm lower than on 700 × 40 (watch pedal strikes).
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.
Front gears1x (32T)One ring, no front derailleur. Adding a front derailleur needs a mount on the seat tube and a 2x crankset, so most riders change the ring size or cassette instead.
Chainring sizeUnknown (now 32T)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 upgrades8 → 9 or 10 speedShimano HG 8/9/10-speed freehub: takes 8, 9 or 10-speed cassettes, Shimano 11-speed MTB and CUES/LinkGlide cassettes (7-speed needs a 4.5 mm spacer; most 11/12-speed road cassettes need an 11-speed road freehub, though the 11-34 HG700/HG800 fit). Shifter,…
Cranks & bottom bracketSquare taper · 73 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 & barstapered steerer · 31.8 mm bar clampAny stem for a tapered 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+.
Seatposts31.6 mmBuy posts in exactly this diameter.
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 Haro Flightline Two 29 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
TiresContinental Contact Urban 700x40 (40-622) wire (pair)
$$$ ★ Our pick
WTB Byway 700x40 (pair)
$$$
Schwalbe Marathon Almotion 700x38 (40-622) V-Guard Addix (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
$$$
ChainKMC Z8.3 6/7/8-speed chain (116 links)
$
KMC X8 8-speed chain with Missing Link
$
KMC X8 EPT 6/7/8-speed anti-rust chain with Missing Link
$$ ★ Our pick
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)
$$
Shimano SM-RT86 Ice-Tech 160 mm 6-bolt rotor (1 rotor)
$$
SeatpostSR Suntour NCX suspension seatpost 31.6 x 350 mm
$$$ ★ Our pick
Redshift ShockStop Endurance suspension seatpost 31.6 mm
$$$$
Cirrus Kinekt 2.1 Aluminum suspension seatpost 31.6 mm (LR or XR spring)
$$$$
Bar & stemRace Face Chester riser bar 31.8 x 740 mm, 25 mm rise
$$
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
$$$
WheelsWeinmann Zac19 700c 6-bolt disc rear wheel, QR 135, 36H, HG 8–10 speed
$$$ ★ Our pick
Stan's NoTubes Crest S2 29 rear wheel, QR 135, 6-bolt, HG
$$$$
HUNT 4 Season Gravel Disc X-Wide wheelset (QR 100/135, HG, Center Lock) + 2 Shimano SM-RT64 160 mm Center Lock rotors
$$$$

Upgrades that fit as-is

Tires

Brakes

Comfort

Control

Utility

Drivetrain

Wheels

Gearing

Fits with small changes (46)

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Buying one used? Fair prices

Worked out from the price new ($650), 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$365–$485$295–$390$240–$315
Good$325–$425$260–$345$210–$280
Fair$265–$350$215–$280$175–$230
Needs work$200–$265$165–$215$130–$175

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

Geometry (size M)

Head angle69°
Seat angle72.5°
Chainstay450°
BB drop64 mm
Wheelbase1136 mm
Head tube100 mm
Seat tube457 mm
Standover740°

Compare with

Sources: Haro: Flightline 2 29 specs + geometry ($649.99) · Haro archive: Flightline Two 29 2021 (earlier version, 3x8)