The Sensor is GT’s 130mm trail 29er bike, which gained a refresh in 2019 and a tweak for 2020. Eagle-eyed readers will notice a similarity with the longer travel 27.5in, 150mm GT Force, with the two bikes sharing various frame parts – including the front triangle.
The Sensor uses GT’s four-bar LTS suspension design and there’s a flip-chip in there to subtly alter the geometry – for testing purposes, I largely left it in its lowest setting.
There’s a flip-chip to adjust the bike’s geometry. Steve Behr / Immediate Media
GT Sensor Carbon frame and suspension details
The Carbon Expert frame has a carbon front triangle that’s mated to an alloy rear, to keep costs in check.
The 130mm travel is controlled by a vertically mounted shock, leaving room for a bottle cage in the main triangle, and an easy to grab little triangle of frame tubes by the top of the seat tube.
The belly of the bike is protected from rock strikes by a down tube protector, which leads nicely to ISCG05 mounts behind the cranks.
There’s no such stock protection for the rear triangle, though, and with a wide back end, I ended up with a fair few scuffs around the rear of the bike from my heels.
Cables sit neatly in the down tube recess. Steve Behr / Immediate Media
Cable routing is neat, travelling along the top of the down tube in a recessed channel, which keeps it out of view but makes maintenance easier, and crucially allows for the SRAM factory brake bleed to be maintained from new.
Despite this, I did experience some cable rattle on rocky descents, which was a little annoying.
GT Sensor Carbon Expert geometry (Low setting)
On paper, the geometry looks bang up to date. The head angle at 65.5 degrees is fairly slack for a trail bike and the 76-degree seat angle isn’t too slouched either (both Low setting).
At 470mm the Sensor has one of the longer reaches in our annual Trail Bike of the Year test, too.
However, the bottom bracket height, even in the Low setting, is fairly lofty at 349mm, and combined with the 480mm seat tube length leaves you sitting high over the bike.
Sizes (* tested): XS, S, M, L*, XL
- Seat tube length: 480mm
- Seat angle: 76 degrees
- Head angle: 65.5 degrees
- Top tube (effective): 620mm
- Reach: 470mm
- Chainstay: 435mm
- Wheelbase: 1,222mm
- Bottom bracket height: 349mm
- Standover: 770mm
- Stack: 602mm
- Head tube length: 118mm
GT Sensor Carbon Expert specifications
Suspension comes from RockShox, with Select+ level dampers in both the 140mm Pike fork and the Super Deluxe shock.
The Pike is a great fork, offering plenty of comfort and control. Steve Behr / Immediate Media
SRAM provides both the drivetrain and the brakes, with a GX/NX mix (sadly, with the lower-spec NX shifter, which doesn’t feel as good as the GX) and G2 RSC brakes – so a pair of high-spec stoppers!
Stan’s No Tubes Flow S1 rims hold the Schwalbe tyres; an Addix Soft Magic Mary up front and a Speedgrip Nobby Nic at the back, both 29in, 2.35in.
GT Sensor Carbon Expert ride impressions
Our 2020 Bike of the Year testing predominantly took place in the South West of the UK through winter. This included loops round trail centres, natural muddy and rooty tracks dug in to Welsh hillsides, as well as laps at BikePark Wales.
A number of bikes were taken to Spain for the final set of tests, where we rode on dry, rocky flow trails, super technical rock gardens and some loamy enduro tracks. Thanks to BlackTown Trails for their help with finding these test tracks!
On bigger hits, the Sensor is calm and composed. Andy Lloyd / Immediate Media
GT Sensor Carbon Expert climbing performance
With the Speedgrip compound rear tyre not offering too much drag, the Sensor climbs fairly well on smoother climbs, especially when seated.
While anti-squat levels are fairly low, the damping of the shock has been upped to compensate for 2020, keeping it all relatively stable most of the time. With a lockout lever on the shock, it’s possible to firm it up yet further, should you wish.
On more technical climbs, again performance was reasonable. The suspension helps keep grip levels high, and the tall bottom bracket height means minimal pedal strikes through rockier terrain.
The bike does feel tall though, and while there’s decent reach figures on paper, this doesn’t completely translate to on-bike feelings, thanks to that high position over the bike.
Still, the bike doesn’t wander around too much on steep pitches and the 50t on the NX Eagle cassette doesn’t give excuses when paired to the 32t chainring.
A SRAM GX Eagle drivetrain keeps the bike rolling, though an NX cassette is slightly hidden in plain sight. Steve Behr / Immediate Media
GT Sensor Carbon Expert descending performance
With the damping levels increased to keep pedalling performance reasonable, I found the rear end a little wooden at times, leaving the bike feeling less agile, poppy and fun than I otherwise might have liked.
This was most noticeable on flatter, more flowy trails where I wanted to play around a little more. That said, the increased rear-end stability means that the bike doesn’t feel sluggish when wanting to accelerate.
A Super Deluxe shock remains consistent in feel on longer descents. Steve Behr / Immediate Media
On steeper descents, where small bump compliance wasn’t as important as big-hit stability, the damped rear-end remained calm and the lack of kickback through the pedals was appreciated thanks to that lower anti-squat.
This leaves the bike feeling very composed and more than capable of picking up a decent lick of speed. I did bang the shock off the bottom of its travel a couple of times, but an extra volume spacer in the shock would sort that easily.
The Magic Mary at the front of the bike also continues to impress, with plenty of grip, support and confidence, mounted to that wider Stan’s Flow rim.
However, the bottom bracket height and the tall 480mm seat tube meant shorter-legged testers found they couldn’t get the saddle low enough, and even those at 182cm had to have the 150mm dropper slammed in the frame.
On the steepest of tracks, or when rolling over a transition into a chute, the tall stature is fairly noticeable.
Once over that hurdle, though, the slack 65.5-degree head angle and long-ish 470mm reach with its 1,222mm wheelbase gave stability, while the 140mm RockShox Pike Select+ fork remained smooth and supportive, aiding grip and confidence.
GT Sensor Carbon Expert bottom line
Save for its wide hips and cable rattle, the Sensor is a really tidy frame and I appreciated the external, yet hidden, cable routing.
The kit bolted on is a bit of a mixed bag; if I could swap the NX cassette and shifter for GX models, I would, even at the expense of having the top-end G2 brakes. Oh, and I’d up the front rotor to a 200mm version at the same time.
While I like the shock’s damping on the climbs, it deadens the rear end a touch, compromising the feel of the bike on flowier trails, but its manners on the steeper stuff are excellent, so long as the saddle is low enough.