The Trek Fuel EX 8 is a mountain bike capable of handling all types terrain. To prove this point our kid was able to test the bike completely in many different locations. From hitting the jumps at the original Red Bull Rampage site in the desert to a junior devo NICA cross-country race in the alpine, the Fuel Ex 8 was up to the task.
Who Is Trek Fuel EX 8 For?
This mountain bike is designed to fit riders 4ft 6in tall (XS) all the way through 6ft 7in tall (XXL). That’s quite a range, isn’t it? A Fox suspension package means the bike is ready to go for trail rides and cross country loops, bike parks, technical terrain and dirt jumps. Novice riders through experts will enjoy riding the Trek Fuel EX 8. If you were to put a pin in the bike spectrum from light-weight cross country racer on the left to downhill freeride machine on the right, we’d place the mark a couple slots to the right of center. Tyge is just a touch over 5ft tall and he was paired with a Small frame with standover height of 27.79 inches.
A Quick Overview Of The Trek Fuel EX 8
Min ~27.55 inches
1 x 12
27.5in (xs, s), 29in (m and up)
~30 lbs sans pedals
Frame Style And Tire Sizes Vary
Because the bike is available in seven different frame sizes, there are a couple of secondary features you should be aware of. The XS and Small sizes will have a curved top tube. This is a great because it will allow shorter riders to comfortably straddle the bike with both feet planted firmly on the ground. This also enables the rider to get a foot down quickly if bumpy or uneven terrain dictates a dab or quick stop. XS and Small frame sizes for the Fuel Ex 8 will also come with 27.5in wheels. This is also a plus in the design-and-fit column. We have seen other brands with XS and Small frames and 29in wheels where the length of the frame is too short and the rider’s foot makes contact with the front wheel of the bike.
About The Trek Knock Block
The Knock Block is a proprietary function of many Trek mountain bikes. This feature is designed into the stem of the bike and it prevents the handlebars from turning 90º. With the addition of the Knock Block, Trek is able to tinker with geometry and ergonomics that result in a bike where the suspension fork cannot strike the frame. Does it limit your turning radius? Technically it does. But not many people are capable of throwing down a 90º turn over a very small distance. Some have mentioned that the Knock Block negatively affects how a bike is stored/transported on a truck’s tailgate or inside a car. This video from Trek explains the Knock Block feature a lot better than we can.
As you may know, Bontrager is Trek’s house brand for components. Some folks are not fans of this approach, but the trade off is a lower overall price for the bike with parts that function very well. Tyge did his best to beat this bike up and it would be reasonable to believe that at the very least – the Bontrager Line Dropper would surrender. But after several months of rough treatment and transport, the dropper works as well as it did when we built up the bike.
Overall the design of the frame is appealing. It’s no-nonsense linkage design is clean and unobtrusive. The front- and rear-wheels are attached to the bike with thru axles. Internal cable routing and an under-the-bar dropper remote keep additional lines on the bike pleasing. Because we have a small version of the frame, there’s not a lot of room to work with for a bottle cage on the down tube. The solution was obtaining a side load bottle cage. You may like the Bontrager Left Side Load Water Bottle Cage for your small frame.
Trek Fuel EX 8 Suspension
A Fox Performance Float EVOL, RE:aktiv 3-position shock with 130mm of travel fills the space for the shock. The fork on the bike is a Fox Rhythm 34, Float EVOL w/air spring and 140mm of travel. Both the shock and fork have lock-out features. We easily added or removed air for the suspension depending on the day’s terrain. And, you can also adjust the rebound for the fork.
Measurements And Angles For The Trek Fuel EX 8 [small]
|Top Tube (effective)
|Seat Tube C-T
Trek Fuel EX 8 – Build Specs
|Alpha Platinum Aluminum, tapered head tube, Knock Block, Control Freak internal routing, downtube guard, ISCG 05, magnesium rocker link, Mino Link, ABP, Boost148, 130mm travel
|Fox Rhythm 34, Float EVOL air spring, GRIP damper, tapered steerer, 44mm offset, Boost110, 15mm Kabolt axle, 140mm travel
|Knock Block Integrated, cartridge bearing, 1-1/8" top, 1.5" bottom
|Fox Performance Float EVOL, RE:aktiv 3-position damper, tuned by Trek Suspension Lab, 210x55mm
|Front: 15x110mm / Rear: 12x148mm
|Bontrager Line Comp 30, Tubeless Ready, 6-bolt
|Bontrager XR4 Team Issue, Tubeless Ready, Inner Strength sidewalls, aramid bead, 120 tpi
|Truvativ Descendant 6k Eagle, DUB
|SRAM DUB, 92mm, PressFit
|SRAM GX Eagle, 12 speed
|SRAM GX Eagle
|SRAM XG-1275 Eagle, 10-50, 12 speed
|SRAM GX Eagle, 12 speed
|Bontrager Line, alloy, 35mm, 27.5mm rise
|Bontrager XR Trail Elite, alloy lock-on
|Bontrager Line, 35mm, Knock Block, 0 degree
|Shimano Deore M6000 hydraulic disc
|Bontrager Arvada, steel rails
|Bontrager Line Dropper, internal routing, 31.6mm
|~30lbs. without pedals
Riding The Trek Fuel Ex 8
Tyge loved the suspension on the bike. He only weighs up to 95 lbs with gear and his flyweight build was a good match for the Fox squish.
We got the right size Fuel EX 8 and it made a difference. Your kids are growing and they’re not going to be on the same bike for more than a season or so. Know that your investment goes beyond the money spent. When you purchase a proper fitting mountain bike for your kids, you’re giving your children the opportunity to enjoy the sport with safety, progression, and fun in mind. Also be aware that a good bike is going to have a good resale value. Families all over are looking for good used bikes and you can usually receive over 70% of what you pay for a new bike.
Tyge loved the tires. He’s never been on 2.6in wide tires before and they immediately granted more control, stability and confidence. On loose surfaces, there was more tire in contact with the ground. On skinnies, there was a wider footprint which resulted in more support and security. Market year 2021 Trek bikes will ship without tubes and with valve stems and rim strips from carbon builds down to the 7-levels. This is good news – tubeless tires out-of-the-box!
The 1×12 Eagle drivetrain has a 50t ring on the cassette and 30t front ring. That provided plenty of pedal power for long, sustained climbs. If your child has not yet experienced a drivetrain with this set-up, they’re going to be pleasantly surprised at the additional climbing and pedaling capabilities the drivetrain provides. Shifting was smooth and simplified.
Riding with flat pedals or clipless pedals was determined by the task. For cross country, some trail riding, and a couple of NICA races, Tyge sported clipless pedals. At the bike park, dirt jumps, and technical terrain – flat pedals were the accessory of choice. We have learned to travel with both sets of foot platforms for extended outings and road trips.
On jumps and bumps, Tyge was able to control the bike very well. Be sure your kid uses the dropper to get that seat out of the way so your can get low on the bike when needed.
Racing the Fuel EX 8 on a couple of Utah’s NICA courses proved to be very fun. The 1x transmission and gear range was very beneficial. And, the dropper was used throughout races. We certainly tightened up the suspension and tires for more grip for one flowy, firm track. On another course with a lot of loose corners and and a layer of dust, the 2.6in wide tires were perfect with lower air pressure. If your kids are cross country speedsters, you can explore additional options in the company’s catalogue that are lighter and have features favored by world-class racers.
Being comfortable with a bike’s geometry allows the rider to progress on technical terrain and in the air. Blend this in with the will to succeed along with finding the right speed and you will get favorable results aboard the Fuel EX 8.
Cornering with the Knock Block technology was not prohibitive and it functioned as engineered by Trek’s design team.
140mm of suspension is plenty for a kid of Tyge’s stature and riding style on big jumps and technical terrain. He could only bottom out the fork and shock if we let out all the air. And, both components had enough range to allow us to tinker with the sag and find the best settings.
The bike really shined after the turns were earned. On open descents, the Fuel EX 8 was is in its element and an extension of the rider.
Braking power provided by Shimano was always reliable and easily controlled. When you get your Fuel EX 8, be sure to set up the cockpit so the levers are at the proper angles for safety and ergonomics. You can reduce finger cramping and arm pump by simply setting the levers up the right way.
Topping Off The Trek Fuel EX 8
Our child enjoyed this bike because he’s a good fit for it literally and figuratively. The size range of the Fuel EX line-up has him covered so we were able to choose the right size, right away. He also has access to a lot of different terrain due to the west’s never-ending mountain bike season. From the rough and please-don’t-tumble red rocks to the flowy NICA race courses, the Fuel EX 8 has what it takes to make its riders happy. The geometry and build are great for beginners through experts who would like to get better at bikes. And, the bike is a good choice for those who are ready to drop a proper amount of money for a machine that will enable kids to grow their love for the outdoors; on bikes – together.