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Selling Fun for 25 Years
Trek FX Sport Carbon 4 (2021) Dark Aquatic/Carbon Smoke
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.
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.
It's right for you if...
You're ready to log big miles, and you prefer the feel of a flat handlebar to the drop bars that come stock on most road bikes. You prioritize comfort and performance equally, and want the simplicity a 1x drivetrain provides.
The tech you get
A lightweight OCLV Carbon frame with a road-smoothing IsoSpeed decoupler, a Shimano GRX 1x11 drivetrain with a wide-range cassette, Shimano hydraulic disc brakes for all-weather stopping power, a lightweight tubeless ready wheelset, and ergonomic grips. Plus, it's easy to accessorize with fenders, lights, and more!
The final word
Fast, capable, comfortable. This bike has a road -smoothing carbon frame and quality parts that will hold up over serious miles, but what really sets this model apart is the simpler shifting experience the 1x11 drivetrain provides.
Why you'll love it
- The 1x drivetrain delivers a wide range of gearing with the simplicity of a single shifter
- You get the superior ride quality of carbon without the bank-breaking price
- IsoSpeed—a decoupler at the seat tube/top tube junction that absorbs fatiguing bumps from the road so you can stay stronger longer
- On your left, roadie! This fitness bike is more than capable of taking on speedy group road rides
- 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|
|Front hub||Formula alloy, centerlock disc, 100x12mm thru-axle|
|Rear hub||Shimano RXC400, centerlock, Shimano 11-speed freehub, 142x12mm thru axle|
|Rim||Bontrager Tubeless Ready Disc, 32-hole, presta valve|
|Spokes||14g, stainless steel, black|
|Tire||Bontrager R1 Hard-Case Lite, wire bead, 60 tpi, 700x32c|
|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|
|Pedal||Wellgo M141, resin body, alloy cage|
|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|
Bontrager Elite, 31.8mm, Blendr compatible, 7 degree, 90mm length
|Size: S, M
Bontrager Elite, 31.8mm clamp, Blendr compatible, 7 degree, 100mm length
|Size: L, XL
Bontrager Elite, 31.8mm clamp, Blendr compatible, 7 degree, 110mm length
|Headset||1-1/8'' threadless, sealed cartridge bearings|
|Brake||Shimano MT201 hydraulic disc, flat mount, 160mm rotor|
|Brake rotor||Shimano RT10, 160mm, centerlock|
|Weight||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).|
Sizing & fit
The charts below show our recommended sizes based on height, but there are some other factors, like arm and leg length, that determine a great fit. That’s why you’ll see some overlap in our recommendations. Not every rider who’s 5´8˝, for example, will fit on the same size bike. The best way to find your perfect fit is to consult the experts at your local Trek retailer.
147.0 - 155.0 cm
4'9.9" - 5'1.0"
69.0 - 73.0 cm
27.2" - 28.7"
155.0 - 165.0 cm
5'1.0" - 5'5.0"
72.0 - 78.0 cm
28.3" - 30.7"
165.0 - 175.0 cm
5'5.0" - 5'8.9"
77.0 - 83.0 cm
30.3" - 32.7"
175.0 - 186.0 cm
5'8.9" - 6'1.2"
82.0 - 88.0 cm
32.3" - 34.6"
186.0 - 197.0 cm
6'1.2" - 6'5.6"
87.0 - 93.0 cm
34.3" - 36.6"
All measurements provided in cm unless otherwise noted.
|Frame size letter||Wheel size||A — Seat tube||B — Seat tube angle||C — Head tube length||D — Head angle||E — Effective top tube||F — Bottom bracket height||G — Bottom bracket drop||H — Chainstay length||I — Offset||J — Trail||K — Wheelbase||L — Standover||M — Frame reach||N — Frame stack|