FX Sport 4 Is Trek’s Carbon Fiber Fitness Bike. Full of Goodies and Under $2K

What is it about carbon fiber that makes everyone want it? Could be the lightweight properties or even the amazing strength. Whatever the reason, Trek knows what you want, possibly even need.
2021 FX Sport Carbon 4 10 photos
Photo: Trek Bicycle Corporation
2021 FX Sport Carbon 42021 FX Sport Carbon 42021 FX Sport Carbon 42021 FX Sport Carbon 42021 FX Sport Carbon 42021 FX Sport Carbon 42021 FX Sport Carbon 42021 FX Sport Carbon 42021 FX Sport Carbon 4
The two-wheeled trinket you see is known as the 2021 FX Sport Carbon 4. Just as the name would imply, it’s a bike made from carbon. Both the frame and fork use this sought-after material. Best of all, it won’t cost you an arm and a leg to acquire. This bike currently cruises in with a price tag of only $1,784.99. Yup, in 2021, that’s all the cash you need to get yourself some bragging rights.

But bragging rights only go so far? Well, I don’t think you got here by coincidence, so keep reading. The first component to take into consideration when looking at any bike, be it electric or not, is the frame. As promised, Trek features a 400 Series OCLV carbon frame that produces a bike, components and all, with a weight of 21.06 lb (9.55 kg). Sure, not the lightest carbon bike out there, but how far did you think that price tag would take you. To please your carbon-tooth, the fork, too, uses FX carbon. Internal cable routing, flat mount disc, and hidden fender mounts are standard.

The lack of suspension on the bike tells you one thing, it’s not meant to leave asphalt, ever. Maybe if you put some gravel tires on it, maybe. But a lack of suspension is something you want when riding tarmac. Why? Simple, no power is lost as you pedal; all of it is transferred to the rear wheel.

2021 FX Sport Carbon 4
Photo: Trek Bicycle Corporation
Ok, so I haven’t been completely honest regarding the lack of suspension on this bike. Aside from the wheels being a source of cushioning, Trek chose to surprise everyone by including an IsoSpeed into the frame construction. What’s an IsoSpeed? To keep it short and sweet, this little gimmick is Trek’s solution to suspension-less bikes.

At the rear of the top tube, where the seat tube and seat stay also meet, a dampening system decouples the seat tube from the top tube, allowing it to flex just enough to eliminate some bumps and vibrations, keeping a rider fresh for longer. Ride harder, ride faster. Hmmm, maybe that could be Trek’s next motto. This team also produces a front Iso, but the component is reserved more for the top-shelf pieces.

The bike itself, is considered a fitness bike by the team, whatever that "fitness” bike means. Honestly, almost any bike can be a fitness bike, depending on your riding style. Heck, I know folks crazy enough to hit a slope with a cruiser, if they need to get their adrenaline kick.

2021 FX Sport Carbon 4
Photo: Trek Bicycle Corporation
As for a drivetrain, an 11-speed setup is furnished. Behind it all, none other than Shimano. An SLX M7000 cassette, GRX RX812 derailleur, and RS700 shifter, help offer smooth shifting, while keeping some cash in your pocket. Braking is also covered by Shimano with a pair of 160 mm (6.3 in) rotors with MT201 brakes fueling stopping power. For everything else, there's Bontrager. Rims, tires, seat post, handlebar, grips, stem...should I keep going?

Personally, I feel it’s a decent bike just right for someone looking to step up their workout routine. who knows, maybe this bike will give you a feel of what the biking world has to offer, and in four years, I’ll be writing a piece about how your triathlon career all started with an FX Sport 4. Might need to change those grips, though.
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About the author: Cristian Curmei
Cristian Curmei profile photo

A bit of a nomad at heart (being born in Europe and raised in several places in the USA), Cristian is enamored with travel trailers, campers and bikes. He also tests and writes about urban means of transportation like scooters, mopeds and e-bikes (when he's not busy hosting our video stories and guides).
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