FX Sport 4 Carbon


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Color: Dark Aquatic

  • Dark Aquatic

Size: Xtra Small

  • Xtra Small
Out of stock
  • FX Sport 4 is a carbon fiber fitness bike for riders who want the speed of a lightweight road bike with the comfort and control of a flat handlebar. An IsoSpeed decoupler smooths out rough roads and the 1x11 drivetrain simplifies shifting without sacrificing gear range, making this high-performance bike perfect for everything from solo workouts to speedy group rides.


    1. The 1x drivetrain delivers a wide range of gearing with the simplicity of a single shifter
    2. You get the superior ride quality of carbon without the bank-breaking price
    3. IsoSpeed—a decoupler at the seat tube/top tube junction that absorbs fatiguing bumps from the road so you can stay stronger longer
    4. On your left, roadie! This fitness bike is more than capable of taking on speedy group road rides
    5. You can pair FX Sport with your smartphone and send your ride data to your favorite fitness app when you add DuoTrap S


  • *spec applies to all sizes unless otherwise noted

    Frame 400 series OCLV carbon, IsoSpeed, internal routing, 3s chain keeper, DuoTrap S compatible, fender mounts, flat mount disc, 142x12mm thru axle
    Fork FX Carbon, threadless alloy steerer, hidden fender mounts, flat mount disc, 405mm axle-to-crown, 100x12mm thru axle
    Hub front Formula alloy, centerlock disc, 100x12mm thru-axle
    Skewer front Bontrager Switch thru axle, removable lever
    Hub rear Shimano RXC400, centerlock, Shimano 11-speed freehub, 142x12mm thru axle
    Skewer rear Bontrager Switch thru axle, removable lever
    Rim Bontrager Tubeless Ready Disc, 32-hole, presta valve
    Spokes 14g stainless steel
    Tire Bontrager R1 Hard-Case Lite, wire bead, 60 tpi, 700x32c
    Max tire size 35c without fenders, 32c with fenders
    Shifter Shimano RS700, 11 speed
    Rear derailleur Shimano GRX RX812, long cage, 42T max cog
    *Crank Size: XS, S
    Shimano GRX RX600, 40T ring, 170mm length
    Size: M, L, XL
    Shimano GRX RX600, 40T ring, 175mm length
    Bottom bracket Shimano BB71, 86.5mm, PressFit
    Cassette Shimano SLX M7000, 11-42, 11 speed
    Chain Shimano HG601
    Pedal Wellgo M141, resin body, alloy cage
    Saddle Bontrager H1
    Seatpost Bontrager alloy, 27.2mm, 12mm offset, 330mm length
    *Handlebar Size: XS, S
    Bontrager Satellite Plus IsoZone, alloy, 31.8mm, 15mm rise, 600mm width
    Size: M, L, XL
    Bontrager Satellite Plus IsoZone, alloy, 31.8mm, 15mm rise, 660mm width
    Grips Bontrager Satellite IsoZone Plus, lock-on, ergonomic
    *Stem Size: XS
    Bontrager Elite, 31.8 mm, Blendr compatible, 7 degree, 90mm length
    Size: S, M
    Bontrager Elite, 31.8 mm, Blendr compatible, 7 degree, 100mm length
    Size: L, XL
    Bontrager Elite, 31.8 mm, Blendr compatible, 7 degree, 110mm length
    Headset 1-1/8'' threadless, sealed cartridge bearings
    *Brake Size: XS, S, M, L, XL
    Shimano hydraulic disc, MT201 lever, UR300 caliper
    Size: XS, S, M, L, XL
    Shimano MT201 hydraulic disc, flat mount, 160mm rotor
    Brake rotor Shimano RT10, centerlock, 160mm
    Weight M - 9.55 kg / 21.06 lbs
    Weight limit This bike has a maximum total weight limit (combined weight of bicycle, rider, and cargo) of 300 pounds (136 kg).

    **Trek Bikes reserve the right to make changes to the product information contained on this site at any time without notice, including with respect to equipment, specifications, models, colours, materials and pricing.

    **Weights are based off pre-production products at time of publication. Weights may vary in final production.

  • Size

    Rider Height



    147 - 155 cm

    4'10" - 5'1"

    69 - 73 cm

    27" - 29"


    155 - 165 cm

    5'1" - 5'5"

    72 - 78 cm

    28" - 31"


    165 - 175 cm

    5'5" - 5'9"

    77 - 83 cm

    30" - 33"


    175 - 186 cm

    5'9" - 6'1"

    82 - 88 cm

    32" - 35"


    186 - 197 cm

    6'1" - 6'6"

    87 - 93 cm

    34" - 37"

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