Trek FX Sport 4 Carbon Review (2021)

Trek FX Sport 4 Carbon

I recently was in the big city of Charlotte NC and swung by a local cycle shop and to my utter shock and amazement they had an FX Sport 4 Carbon in stock.  This bike shop also asked if I were a veteran and gave me a 10% discount off retail price as well.

Ever since the pandemic hit one of the first things to disappear from the earth, after toilet paper, were bicycles.  IF, and I mean IF you could find a bike it wasn’t one of the higher end bikes.

Much like a lot of other people in the world I decided to whip myself into shape after being allowed to telework which gave me a solid two extra hours in the morning to exercise.  And what I most wanted was a Carbon Trek FX Sport 4, 5, or 6.  They have been unobtanium, at least in my parts, for over 2 years now.

I decided to buy the bike despite the fact that I have an FX2 and a Verve 3.  Here are my thoughts on the bike after dabbling with it for a few days.

I simply CANNOT regurgitate specifications on my blog.  You can look up the specifications yourself.  Repeating them helps no one.  My job is to give a real world analysis of what isn’t common knowledge or what isn’t in the manual.  Here’s a quick vid cap of my bike.

And here is the first fun fact that I learned after purchasing the bike.  YOU CAN’T PUT A REAR RACK ON IT.  Trek has a compatibility chart for fenders, racks, and kickstands, but it is buried well on their web site.  The FX4 Carbon will take fenders but it will not take a rack or kickstand.

Trek Chart (click to enlarge)

Call me crazy but even though I wanted a sexy road bike I still want a rear rack.  I probably overcompensate but I carry enough stuff to fix about any problem to return home.  Flat tires are not the only thing that can go wrong with a bike.

So anyway, if you have to have a rear rack and pannier system the FX Sport 4 Carbon is not for you.  Also the group is 1 x 11 and my maiden voyage was a crazy hilly ride.  The granny gear end of the bike is great, and maybe a little too great. Even on hard ascents I found myself on the 3rd ring down.   On the wicked descents I found a couple of times that I had to coast because I couldn’t spin fast enough.   This sounds like a negative, and maybe it is,  but my typical exercise ride is a 25 miler from my house in the country to even further out in the country.  I think we could describe my ride as “Fairly Flat” and 99% of my rides will be done in my general area of flatness and the group and gearing are more than adequate and in fact PERFECT for my topography that I encounter.

If you are a hill monster you may definitely want an FX 5 (2×10) or 6 (2×11).  Or you may prefer a more traditional drop bar road bike.  I like the more upright style of the flat bar.

The bike is the most silent bike I have ever ridden and the Shimano GRX group (gravel) shifted flawlessly.  I’m excited about the gravel set up because on some of my course modifications I ride down a gravel road that is about a 1 1/2 miles long (3 miles total on gravel) in a North Carolina Forestry area on Brices Creek near my home.   This makes the bike even more specific to my needs.

This is the best shifting bike I have ever ridden.  While my FX 2 shifts well in the most common ranges I use it shifts like a dog on the low end of the gears.  Adjust it out and the problem moves somewhere else.

I haven’t previously owned a Carbon bike and the ride is certainly different.  I noticed less pain and less muscle fatigue.  This may have been due to Trek’s IsoSpeed Decoupler.  I am the furthest thing there is from a pro rider and I should have been sore and stiff from my hill ride and yet I wasn’t.  For some reason there was a lot less road shock to my arms and I definitely have wrist issues when I ride.  Anyway I am tickled with the level of comfort but anxious to get the bike home and ride it on my usual route.

It also is DuoTrap S compatible but I don’t think I’ll use this as I have a Garmin 530 bike computer and ride with an Apple Watch as well.  I log all my rides to both Garmin Connect and Strava.  If one computer fails I have some redundancy.   No need for a third computer.  I have always been of the opinion that I’d rather crash and burn and wreck a bike computer than an iPhone.

Anyway,  I feel like Trek hit a three run homer with this bike and just shy of a Grand Slam.  And I make that statement relative to my needs wants, and desires, not yours.  While this is indeed a sexy, flat bar road bike it seems mission oriented to a specific style of riding.  Fortunately the setup mirrors what my ride profile is.  I love this bike and I’m not just saying that because I’m giddy with my new purchase.   I ride flat with the occasional gravel road and I ride more upright.

If I could put a rear rack on this thing I’d be even more happy.  Probably have to get a seat post rack or ride with a slim profile backpack.


4 thoughts on “Trek FX Sport 4 Carbon Review (2021)

  1. JJ Savilonis

    Everything you say is true! I bought one and my only negative is that a standard rack won’t fit. I’m looking at a seat stay mounted rack, but the seat post style might be recommended for a carbon frame?? Looking into that…
    The bike is smooth and it has proven to be very comfortable on a 40 mile ride!

  2. Dave presotto

    I got a seat post rack with mine. Works fine with a pair of Ortlieb panniers though at my age it sits high enough that i have to tilt the bike way over to swing my leg over it. I too was unpleasantly surprised that i couldn’t mount a rack.

  3. Kevin


    I am actually buying this buying this bike right now as it’s on the trek florida site for $1500 and I thought that was a steel for this setup and a carbon bike. I wish it had a few other things as well.. ability to have a little bigger tire if I choose later and the under mounting bag connectors like the new carbons have. They are minor so I will accept the features…

    Now, as for the rear rack, I found a site that allows you to switch out that rear pin and put a pin in to help you mount a rack!

    The link is above and I am probably going to do this as well. I like your idea of always having a go pro. pretty smart actually. I think I invest in a mount for mine as well.

    Thanks for your review. It was helpful in my decision making process 🙂


Leave a Reply

Your email address will not be published. Required fields are marked *