Great geometry; good tyres
Short travel dropper; small rotors hold it back
Sonder’s Signal ST steel hardtail mountain bike sticks to the British brand’s value for money recipe while catering for the hardest chargers thanks to its modern, descent-focused geometry and collection of tough but high-performing parts.
Sonder Signal ST NX frame and geometry
Built from 4130 series steel, the Signal’s geometry hits all the typical numbers for a modern aggressive trail bike, with this large having a reach of 465mm, a head angle of 66 degrees and a seat angle of 74 degrees.
While none of these are at the most extreme end of what we’re seeing elsewhere, all are in the range you’d expect for a bike with intentions to hammer down difficult trails and still winch back up in some comfort.
The dropper cable is internally routed, but the brake hose and gear cable run externally. The top tube slopes downwards from the head tube to seat tube, to increase standover clearance, with a brace added to the seat tube.
The tapered head tube has its bearings mounted directly inside, negating the need for a headset, and there’s a threaded bottom bracket. However, there are no chain device mounting tabs.
One bottle cage mount sits low enough on the down tube for a bottle and a frame bag to fit.
Seat angle (degrees)
Head angle (degrees)
Seat tube (cm)
Top tube (cm)
Head tube (cm)
Bottom bracket drop (cm)
Sonder Signal ST NX kit
The Signal is fitted with a full SRAM NX Eagle 12-speed drivetrain with a 10-50t cassette and 170mm crankset that sports a 32t chainring.
SRAM Guide T brakes take care of stopping, with a 180mm rotor up front and 160mm at the back.
The 130mm travel RockShox Revelation RC fork comes with an air spring, the ‘RC’ denoting its externally adjustable rebound and compression damping. The compression circuit can be almost completely closed to reduce bobbing on smoother climbs, too.
The Sonder Abode saddle sits on top of a 125mm drop X-Fusion Manic dropper post, activated by an under bar-mounted lever.
The own-brand Sonder Aspect Riser bar has 15mm rise, is 780mm wide and is matched to a Love Mud Piskie 35mm stem.
Rolling duties are performed by Sonder Nova 29 wheels wrapped in a WTB Vigilante Light High Grip carcass 2.5in tyre on the front and a Trail Boss Tough Fast Rolling 2.4in tyre on the rear.
Sonder Signal ST NX ride impressions
The Signal feels weighty thanks to its sturdy 4130 steel frame and wheels, and the reassuringly burly Sonder-branded rims and WTB tyres that weigh 2.3kg combined.
However, the weight immediately becomes less significant as soon as the tyres touch dirt, and the relatively steep seat angle helps to keep weight forward for a comfortable climbing position.
While the Sonder is never going to be XC bike fast uphill, that’s not really the bike’s intended use.
Instead, it spins comfortably up fire roads and climbs confidently over steep, tech sections where the tyres’ thick carcasses help traction where lighter casings can suffer. It won’t be the fastest to the top, but for many riders that’s not the goal anyway.
Once heading downhill and with the slightest bit of gravity assistance, the Signal starts pulling at the leash. Rolling trails and moderate gradients are dispatched comfortably, only requiring a little momentum to reveal its playful nature.
Pumping and pedalling wherever possible helps the bike get up to speed and it rides across roots in a manner that a hardtail has no right to.
The geometry and tyres add up to a highly capable technical trail machine and the planted nature of the Signal means it can approach sections at the top of a rider’s capability – it won’t be the bike you’ll lack faith in.
If there’s grip to be found, the WTB boots help to find it. Dropping into sketchy chutes or hitting corners with minimal support was a question of testing my own limits, and the fun factor rose sharply.
The fork operates well in most circumstances, taking light and medium impacts at most speeds and rebounding in time for the next due to good mid-stroke support.
However, it does bottom-out harshly on bigger hits through larger bumps, rather than jumps gone wrong or big drops.
Despite some tinkering with air pressure and compression damping, I was unable to remedy the issue, but installing air spring volume reducer tokens could help by increasing ramp-up towards the end of the fork’s travel.
I’d prefer a longer travel seatpost because while the 125mm drops the saddle a good way, it’s still high enough to annoyingly brush my backside in the sketchiest situations.
Larger brake rotors would be appreciated too. For a bike with such good habits on terrain where speed can build rapidly if things take a turn for the worse, the more braking power available the better.
Sonder Signal ST NX bottom line
The Signal fits well into Sonder’s value-centric range. At just under £1,600 you’re getting a good frame that combines a relatively inexpensive, durable material with great geometry for a chassis that wouldn’t look out of place with much higher-spec parts.
The build prioritises areas, such as the brilliant tyres and the solid fork, to give the optimal ride for the money without too much compromise elsewhere.
The Signal ST NX is a bike that’s focused on getting you to the top in your own sweet time and then letting it all hang out on the way back down.