As part of a head-to-head review feature, Rob’s been testing two 130mm travel 29er trail bikes; the 2019 GT Sensor Expert and the 2019 Trek Fuel EX 9.7. So which one has come out on top? Read on for Rob’s review of the GT Sensor Expert.
The history of GT is vast, and the success it’s enjoyed across all disciplines over the decades really has few equals. In recent years however, it would be fair to say that the iconic American brand has slipped down the pecking order somewhat.
After a few years of being idle in the Trail and All Mountain categories, GT is hitting back with not one, but two entirely new bikes: the revamped Force and Sensor. For this review, we’re looking at the shorter travel bike of the two, the Sensor, and in this specific case, the GT Sensor Expert.
In redesigning the Sensor from the ground up, GT has ditched the previous AOS suspension design, rewinding the years and returning to the LTS (Linkage Tuned Suspension) name that is so synonymous with the GT bikes of old. Instead of the floating BB found on the AOS and i-Drive platforms, the new Sensor gets a proven four-bar Horst link suspension design.
Unlike other brands that offer bikes in a huge number of specs and models, GT offers the Sensor in just five. Two alloy framed iterations, and three carbon framed versions.
The GT Sensor Expert sits in the middle of the bunch and is equipped with a carbon front end, and a welded alloy rear. Finished in a deep shade of Châteauneuf Du Pape, set off with yellow decals, it’s going to split the opinions. And if the paint job doesn’t, surely the gum wall tyres will.
As mentioned above, the Sensor runs a four-bar suspension system, activated by Horst links on the chainstays and delivering 130mm of travel. Although we’re used to seeing four-bar suspension platforms now, and whist some may suggest that GT has simply copied other manufacturers, is that necessarily a bad thing? It’s a proven system that works, and there is plenty of room for originality within the system when it comes down to kinematic design.
A Closer Look At The GT Sensor Expert
With a 65.5° head angle, this ain’t no XC whippet, but with 29in wheels and 130mm of travel, it also isn’t an enduro ripper. Because of that, the Sensor aims to slot right into the do-it-all trail bike category.
Looking after suspension, a trunnion-mounted RockShox Deluxe RT3 rear shock offers two positions of damping and buttery smooth action from the DebonAir spring. Up front, a RockShox Revelation RC also supplies 130mm of travel, fitted with the Charger damper.
There are a few super neat frame details on the Sensor that we’ve got to take a look at.
Down at the base of the shock, neatly set into the carbon frame, we find a flip-chip. This allows riders to adjust the head angle of the Sensor by 0.5°, and drop or raise the BB height by around 7mm. All of which can be done whilst out on the trail, using an Allen key on your multitool.
Other numbers to note are a seat angle of 76°, a reach figure of 495mm (X-Large) and 435mm chainstays.
We’ve also got the ‘groove tube’ on the carbon version of the Sensor, which is a recessed section on the down tube. This houses cables for the rear mech, rear brake and dropper post, giving the Sensor a clean silhouette. Unfortunately, this isn’t a feature on the alloy frame though. Everything other than the stealth dropper post uses external cable routing, which is an incredibly refreshing bit of design to see. Easy to get at, and easy to maintain.
Although GT has updated the suspension platform and overall aesthetic on the new Sensor, it has kept GT lovers happy by sticking with the ever-recognisable Triple Triangle frame design, finished off with the seat tube support.
GT has spec’d brakes from SRAM, in the shape of the Level TLs. For rolling, we’ve got Stans NoTubes Flow S1 wheels wrapped with Schwalbe Nobby Nics (more on those later). The drivetrain is a mix of a GX Eagle shifter and chain, with a Truvativ Descendent Carbon crankset, and it’s pimped up with a X01 rear mech and cassette.
Setting Up The GT Sensor Expert
To suit my 6’2″ (188cm) stature, I’ve got an XL on test here. It’s the biggest that GT offers, and with the huge space in the main frame in this size it does look big.
Straight out of the box though, the Sensor felt great for my 6’2″ height. Yeah, it’s big – but it doesn’t feel overly so. The length feels comfortable, and when riding it feels stable. The 780mm wide bar on this bike is a good match for the aggressive geometry.
I kicked off the testing with the flip-chip set to low, which is the slacker of the two settings, offering a 65.5° head angle. Throughout the test I wanted to play around with the flip-chip to see how the bike would perform in each setting. From the get-go I set the suspension up pretty firm. That suits my style of riding, especially at bike parks and on flowy trail centre loops.
If I’m honest, I’m not a huge faffer when it comes to bikes. I just want to go play, which is exactly what I did with the Sensor, and this is what made me really start to love this bike from the get go. I setup the fork to 95psi as per RockShox’ guidelines, aired up the shock to 200psi for 30% sag, kicked the tyres, and was off.
The Sensor bounded along like a big friendly horse. Not particularly clever, but it just wanted to make you smile.
Uphill, the suspension feels firm and supportive, with barely any bob at all – it feels so stable and composed. The 3-position shock does give you Open/Pedal/Lock settings. For me though, once it was set up, I happily left it in the open position and let it do it’s job.
Even with the flip-chip set in the slacker of the two positions, the bike feels plenty comfortable pointed uphill. When in position, the bike really doesn’t feel like an XL. The reach is comfortable both climbing and cruising, and the out-of-the-box cockpit is spot on.
I’ve got a whole heap of riding locally, but I started out at the Leeds Urban Bike Park to be precise. Here the harder compound Nobby Nic tyres rolled fast and true, and the Sensor skipped along the hard-packed surfaces.
On fireroad climbs, the GT Sensor sets about its business in a very quiet and unfussy way. The big 50t spinner on the Eagle cassette allows you to comfortably sit and spin away without breaking a sweat. Surprisingly, the slacker front end on the Sensor doesn’t feel wayward in any way and I’ve not had many instances where weight distribution has caused the front end to rear up when climbing over rocks or roots.
The firm suspension also keeps the bike riding high, and I had no issues with pedal strikes. However, the flip-side to the supportive suspension is that it isn’t as comfortable or sensitive on rougher trail surfaces. The firm feel means it bounces around on the rocks more compared to the uber-smooth Trek Fuel EX, so line choice on techy climbs becomes more important to ensure consistent traction.
One thing to note is the chunky seat stays. This was something I didn’t pick up at first, but after a friend had a ride on the Sensor and informed me of, I began to notice. On the climbs, and when coming over the pedal rotation I was beginning to catch my heels on the seat stays. When looking from above, the alloy tubes around here are pretty hefty. Great for stiffness and rigidity, but if you’re a heels-in rider that owns bulky skate-style shoes, you might experience some contact.
Pointing this thing downhill is where I’ve absolutely loved my time riding it. Whether it be in a bike park, or at the top of a huge climb, the eager character of the Sensor is just so addictive. It really wants to go as fast as you dare let it, even if that’s going to lead you into some trouble.
The RockShox Revelation has struggled at times, feeling a touch flexy and out of its depth on the really rowdy trails. On flowy single track, tight corners and hard packed trails through – this bike charges so hard. The suspension has very usable support through the mid stroke, and it’ll work plenty hard when you really get going. If you’re one for finding fun lips and gaps on every trail, the GT Sensor Expert will put a smile ear-to-ear. Even with the frame size on the XL looking massive when stationary, when you get on the move it’s been really surprising to find just how much you can move around on this bike.
If you were to look at the spec, wheelsize and travel on paper, the Sensor may not seem a whole lot different to other trail bikes. But once on the trails and especially when the flip-chip is set to low, the geometry on this bike works very well. It’s such a confident bike, and I can only imagine of what it would be like with a better fork and more powerful brakes.
Flipping the flip-chip is a touch faffy, but once you’ve got the tools to go, it only takes a few minutes. You’ll need both a 4mm and 5mm Allen key, which is a bit annoying if you’ve only got one multi-tool that can’t be dismantled.
Use a 4mm for the drive side, 5mm for the passenger side, turn simultaneously and you’re in. Pull bike shock up, flip the gold tabs around then screw the bolts back through and you’re away. I was actually really surprised at how noticeable the changes were once I’d swapped from the low setting to high. That 0.5° change in head angle, and the 8mm increase in bottom braked height really changes the riding position. On climbs, you feel taller and more upright, with plenty of clearance under the pedals which has resulted in near to no pedal striking.
Even when cranking along and dropping into descents in the high position, I wouldn’t say there was a time where I felt out of control. On the super steep stuff, the front end can tuck under more, but slamming your weight right back over the saddle and keeping the speed down keeps you in control. Even in the ‘high’ setting, a still relatively slack 66° head angle isn’t exactly going to throw you head first over the bars.
I must say that the frame on the GT Sensor is very impressive. GT has clearly taken a lot of time to design and develop the carbon front triangle, and that is noticeable. There is plenty of room out back for a wider tyre (we’ve been running 2.35in Schwalbes here), and with that loads of mud clearance too for sloppy British winter conditions.
The Groove Tube is a neat design feature and keeps cables super tidy, all while being pretty much silent. Other bike manufactures could do with taking this approach on board, rather than making everything internally routed.
One of my reservations with the Sensor is the idea that GT has spent so much time and money developing the fancy carbon frame, that it has sacrificed the spec in places. For me, the brakes are nowhere near powerful enough to handle the capabilities of a bike like this. The SRAM Level TLs should be upgraded to Guides without any hesitation, or better yet, Codes.
And on that note, while the SRAM X01 mech and cassette shift well, I can’t help but feel that a full GX Eagle drivetrain would have saved a bit of cash to put into better brakes.
Although nothing has really broken or gone wrong on the GT Sensor Expert during testing, there are a few notes to make. This isn’t a particularly quiet bike. There is a lot of chainslap from the rear end, which causes a lot of noise and there has been some subtle grinding noises coming from the bottom bracket area.
Not a durability note – but the axles on the Sensor are Allen key operated both front and rear. Although it looks clean, the pain of getting the Allen keys out every time you want to load up the bikes into the car may become tiring. The rear axle is also a bit of a faff to get lined up when bolting the wheel back into place. You’ve got to give the wheel a good shove to get it into position, and then slam the axle through to make sure it’s in place.
Other things to note are a few chips in the paintwork around the dropouts and on the rear triangle. The brake levers have also developed a creaking sound when pulled back towards the bar under harsh braking.
Three Things That Could Be Improved
- A bike that has the ability to go this fast, needs more powerful brakes
- The carbon frame, cranks and X01 bits are lovely, but that cash might be better spent elsewhere
- While the Schwalbe tyres work fine on trail centre type terrain, they are very light. Rubber crushers will want burlier casings
Three Things I Loved
- The Marmite looks may split opinion, but I’m a huge fan of the Sensor’s aesthetics
- Confidence-inspiring geometry makes you want to charge hard and travel downhill as fast as possible
- The get-up-and-go nature of this bike is contagious. It’s just great fun
The GT Sensor is a riot. It’s quick, it’s planted and it’s a whole load of fun.
The spec does feel slightly compromised, which I think is down to the fancy carbon frame. The brakes are nowhere near powerful enough to control a bike that wants to rail as quick as this one does, and the fork does feel as if it’s getting out of its depth slightly on the rougher stuff. Other than those spec niggles, the ‘get out and ride’ nature of this bike is what I absolutely love about it. If you’re happy to spend an extra bit of cash to upgrade some of the components on the Sensor, you’re in for a good time.
Sure, it’s not as technologically striking as other bikes on the market, but damn does it make you smile. And for me, that’s what it’s all about. Bikes are for riding with mates and having laugh – and the Sensor does that brilliantly.
2019 GT Sensor Expert
- Frame // Carbon Fibre Mainframe & Alloy Rear, 130mm Travel
- Fork // RockShox Revelation RC, Charger Damper, 130mm Travel
- Shock // RockShox Deluxe RT3, DebonAir, 185x50mm
- Hubs // All Terra Alloy Disc 15×110 Front, 12×148 Rear
- Rims // Stan’s NoTubes Flow S1, 32h, Tubeless Ready
- Tyres // Schwalbe Nobby Nic Performance 29×2.35in Addix Speedgrip compound
- Chainset // Truvativ Descendant 7K, Dub, 32T
- Rear Mech // SRAM X01 Eagle, 12-Speed
- Shifter // SRAM GX Eagle, 12-Speed
- Cassette // SRAM XG-1295, X01 Eagle, 10-50, 12-speed
- Brakes // SRAM Level TL, 180mm Centerline Rotors Front & Rear
- Bar // All Terra Alloy Riser, 15mm rise, 780mm width
- Stem // All Terra, 31.8mm, 7° Rise, 60mm Length
- Grips // GT Statement Single Lock-on Grips
- Seatpost // KS Lev Si dropper, Southpaw Lever, 150mm Travel
- Saddle // Fabric Scoop Shallow Sport
- Size Tested // XL
- Sizes available // Small, Medium, Large & Extra Large
- Confirmed Weight // 14.5kg (31.9lbs)
- RRP // £3,299
- From // GT Bicycles
|Tested:||by Rob Mitchell for 3 Months|