Choosing between the Trek FX3 and the Trek FX4 is no easy decision. So, if you’re in that tricky spot today, then I feel your pain and I’m here to help make the choice a little easier for you.

First up, I’ll take you through the full specification list for each bike, with a head-to-head comparison so you can see how they each measure up. Then, I’ll do a deep dive on the two bikes with a full review and I’ll look at what you get for your money and give my opinion on which gives the best value.

If you’re short on time, then here’s my recommendation: go with the Trek FX 3 Disc. My view is that this is the perfect hybrid bike at a great price for smooth roads or pavement, when you like to travel fast and are maybe considering using your bike to commute to the office.

If you’d like to take a look at a little more explanation behind that recommendation, then stick around!

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Trek FX overview

Whichever flavor of Trek FX you buy, you can be confident that you’re getting a bike with a host of great components from a manufacturer with a solid pedigree.

Bike chat tends to be all about whether you’re a “roadie” (a road bike cyclist who zips along on skinny tires whilst wearing tight spandex outfits) or a mountain biker (blasting down gnarly single track trails on a machine with full suspension and knobbly tires, whilst wearing baggy cycling outfits and a full-face helmet).

But that skips over the huge middle ground that’s occupied by everyone else who wants to cruise along smooth pavement on a super-light bike that’s comfy to ride, with tires that are slim not skinny, with just enough grip but not outrageous. Oh, and whilst wearing whatever they want. No spandex in sight. Maybe denim, maybe even a swimsuit, possibly sneakers or flip flops. And definitely with a big grin on their faces.

That’s where hybrid bikes come into their own and the FX from Trek is one of the best on the market.

I’ve compared the FX before with Trek’s other great hybrid, the Dual Sport. Both are great bikes and the key difference between the two of them lies in the front forks. Dual Sport bikes have a front suspension fork and that means that they work well on both smooth surfaces, like roads, and are also capable of handling off-road trails, with loose and bumpy terrain. FX bikes have a rigid fork by comparison. This saves a considerable amount of weight off the bike, meaning you can zip along faster and lifting your bike is a breeze. And it also means that the FX is the perfect bike when you’re exclusively riding on smooth pavement or roads.

Let’s take a look at the details on the FX3 and FX4 and see how they stack up next to each other.

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Trek FX3 review

The Trek FX3 is a highly capable machine with an awesome specification list and a bike weight of under 26 lbs.

The FX1, FX1 Disc, and FX2 Disc have great components on a super-light frame but, when you move to the FX3, things start getting really exciting.

The alloy front forks of the FX2 Disc are replaced with carbon fiber. This reduces bike weight by a decent chunk and it has an additional benefit in giving the forks a little extra flex to reduce vibration to your hands and arms.

The brakes are hydraulic disc, so you’ve got incredible stopping power in a responsive form. Disc brakes are less impacted by surface water, grease or mud, in the way that linear-pull brakes are. If you’ve ever ridden through puddles with linear brakes, and then tried to do an emergency stop, you’ll know what I mean by this. Disc brakes come in two forms – hydraulic and mechanical – and the FX3 has the best type, hydraulic. Hydraulic disc brakes being lighter than mechanical.

Ride style on all the FX bikes is laidback, upright and super-comfy. Everything’s tidy, with the cables being routed internally through the frame (rather than externally where they could snag), and there are fixings built in for cargo racks, kickstand, and fenders.

The tires on the FX3 are 700x32c. Compare these with the much narrower tires on my road bike (at a tiny 700x23c) and you feel a big difference in comfort on the road. Hard, narrow road bike tires let you feel ever speck of dirt or grit lying on the road. But, with a more generous 700x32c tire and a lower tire pressure, you can sail comfortably over uneven surfaces without feeling a thing.

It’s got a wolf’s list of components, wrapped up in sheep’s-clothing hybrid bike form, and then finished in a wolf’s paint job, of either Dnister Black or (my favorite) Rage Red. Wow.

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Trek FX4 review

There’s around a $150 price difference between the FX3 and FX4. So, let’s take a look at the differences between the two bikes and whether these justify the extra dollars.

Sit the two side by side and you might be hard pushed to see anything obvious. The FX3 has two color choices (the Dnister Black and Rage Red) and the FX4 is available in just the one color. Though it’s a rather awesome fade from the Dnister Black to Radioactive Red.

Most of the components on the two bikes are the exact same, but look a little closer and you’ll notice that something’s actually missing on the FX4. It’s the front derailleur.

The front derailleur is the bit of mechanical wizardry that shifts the chain between the cogs at the crank (by the pedals). The FX4 does away with this by having additional cogs at the rear and a single cog at the front, giving it 11 gears in total vs the FX3 at 2×9 = 18 gears. It’s a move that’s in line with the current trend on bikes, which is to simplify the gearing.

Back in the day, the view used to be that, the more gears a bike had, the better it was. But, actually, some of the gears you couldn’t actually use, and most of them you’d never need to use. So there was quite a bit of redundancy.

The FX4 recognizes this and gives you 11 gears that cover a similar range to the FX3. The advantage is that the entire system is much simpler – one less derailleur, less cogs at the crank, one less gear shifter – so it’s easier to operate, there’s less to go wrong and need fixing, and it weighs less.

Does this mean that the FX4 pips the FX3 at the post? It depends. If you ride (or are planning to ride) only now and again, then it probably won’t and you might be best hanging on to the extra cash. However, if you plan to take the bike out regularly, possibly commuting on it as well, then it will definitely make a difference. Fewer things to go wrong means that you’ll get fewer repair bills (or bike downtime) and, if you are getting lots of miles in, then repair bills could quickly add up to the price differential between these two bikes.

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Conclusion – which one to go for?

So, which one are you going to choose?

Here’s my suggestion. If you plan to take your bike out occasionally for a few miles at a time, then I’d go with the FX3 and keep the extra cash in your back pocket. If you are going to be going out more regularly, possibly commuting, and for longer journeys, then you’ll appreciate the higher spec of the FX4.

At the end of the day, both bikes are excellent. Buy the FX3 and you’re like to be very happy. Buy the FX4? Guess what, you’re likely to be really happy too. As I said at the top of the page, Trek have made a couple of great bikes with these and you’ll have fun riding whichever one you go for.

Happy cycling!