”The dawn of a new era” – says Trek when introducing the new electric Fuel EX-e. Why is that? The Fuel EX-e is a superlight emtb with a small motor and battery. Such bikes have been around for a few years. What makes the Trek Fuel EX-e so special? Watch the video reviews or keep reading below.
Introduction
The new Fuel EX-e is a full suspension 29er bike. It’s only available with a carbon frame. The fork has 150 mm of travel while the rear end offers 140 mm. We test Fuel EX-e XX1 AXS, the top-of-the-line model at about 19 kg without pedals.
This isn’t the lightest of the superlight bikes. It’s equipped with solid components. Fork and tyres are relatively burly. There is even a minitool inside the steerer tube. These are things you don’t get on the lightest bikes. It seems function is top priority for the Fuel EX-e.
TQ HPR50 motor
The HPR50 motor is manufactured by the German company, TQ. It’s a 250 W motor with 50 Nm and 300 W maximum power. Weight is just 1.85 kg for this compact motor. The design of the motor is interesting. The crank axle is located in the center of the motor. This allows for a more compact motor design. But it can affect the chainstay length. See our video review of the motor for more details.
Removable battery
The 360 Wh in-frame battery can be removed by unscrewing two screws. This is unusual for a superlight emtb. The manufacturers go with fixed batteries, probably because it’s an easier solution that saves weight. There is also a range extender, a 160 Wh battery that fits the bottlecage.
The range extender. This bottle shaped battery adds another 160 Wh. 
The compact 50 Nm TQ HPR50 motor.
Geometry
Even with a motor with the axle in the middle, chainstay length is nice and short. We think 440 mm is the perfect length for this bike. Steep seat tube angles have been common the last few years. It’s 77* degrees on the Fuel EX-e. Head tube angle is 65*, nice and slack for a light trail bike. Wheelbase is 1.247 mm on the size Large test bike. This tells us the frame is quite long.
Introducing the Trek Fuel EX-e models
There are 6 different levels of equipment. The four more expensive bikes get wide 820 mm handlebars with an integrated stem. The two cheaper ones get narrower handlebars and less agressive tyres. We think the 9.7 model looks like the better buy, but why does it come with 170 mm crank arms? Is it a misprint? The five other models all have 165 mm crank arms. That’s nice when the Mino Link is set to “low”.
Prices
There are few cheap bikes in the Super Light category. The 9.9 AXS testbike is among the most expensive ones at £ 13.250. Thankfully, there are cheaper models available. Most bikes are available as “Project One”, noted as P1 in the price list. Here you can chose between countless color combinations, and you can alter the specs. The £ 5.750 Fuel EX-e 9.5 is a fork and a couple of brakes away from being fine for me. Oh, and wider handlebars.
Trek Fuel EX-e – a new era?
We think a superlight emtb shuold feel light and nimble, like an unassisted mountainbike does. Several brands make such bikes, and we think they work well. But they don’t feel truly unassisted. We can feel the motor engaging. We can feel the push when we barely pedal, or sometimes when we don’t pedal at all. This affects the ride feel and our riding technique.
Trek Fuel EX-e 9.7 
Fuel EX-e 9.8 
Fuel EX-e 9.9
TQ have succeeded with their motor. We put it to our regular tests and we aren’t able to determine the exact moment the motor activates. Some times, we don’t notice the motor untill we stop pedalling and the assistance deactivates. More about this test and other details in our video review of the HPR50. The motor rarely misbehaves, so we don’t notice it much while riding. The same can be said for the noise level. If we pedal below say 80 rpm, we can only hear the tyre and drivetrain noise.
The motor feels like nothing else we’ve tested. The “new era that is dawning” could be about a superlight emtb feeling more like an unassisted trail bike. Does that mean Trek have targeted eager mountainbikers that have prefered trailbikes without assistance? Perhaps. But even ebikers such as us had a great time on the Fuel EX-e. Will this kind of ebikes dominate mountainbiking? Trek believes so, it will be interesting to see.
Going up
It seems the TQ HPR50 motor in the Trek Fuel EX-e doesn’t use all available power. Default setting appears to be 156% amplification of rider input. We’re not getting the claimed 200% amplification. This can be altered using the Trek Central app, but it’s not ready yet. So, expectations are low as we approach the first climb.
Have we actually got assistance? We’re not sure initially, even though we’re running the highest mode. After a while, we’re sure we’ve got a good ammount of help. My Trek contact says the motor i programmed to read rider behaviour and adapt to it. We can’t find further info on this. All we can say is that the motor felt fine after a bit of climbing and we never experienced this again.
The bike inspired us to push harder. So, we put in more effort than we usually do. Still, it feels easy, it feels just right. Even though the 440 mm chainstays are relatively short, the bike climbs well. The steep seat tube and wide handlebars pulls the rider weight forwards. It ensures the front wheel stays planted. Doing technical climbs takes a bit of getting used to though. The motor isn’t pushing us over the obstacles like we’re used to.
On the flats
An allround trailbike is of course at home on flatter trails. The Fuel EX-e feels more lightweight than the scale had us believing. Even with the wide handlebars, the steering is fast and precise. It’s easy getting up to the speed needed to gap bumps and obstacles on the trails.
Then down
We ride a few descents, and we forget to notice if the Fuel EX-e feels like a stable ride. An emtb usually is confidence inspiring and safe. But the ride is too fun and exciting, we use the entire width of the trails in search of entertaining lines. We finally try straightlining a bit, and the Fuel EX-e really is surprisingly stable. It’s not the same as a heavy, full-fat emtb. Still, this is very good.
Conclusion
The Trek Fuel EX-e and the TQ-motor comes even closer to the feeling of riding an unassisted bike. It’s not the most lightweight emtb, and not the most powerful. But it’s specced with solid components, and it inspires us to pedal harder on the trails.
