Stealth F-37 (2023 - ) review

Because it’s not restricted in power or performance the Stealth is built more like a motorbike than an e-bike, with a sturdy steel frame containing a hefty 1.5kWh battery that’s much bigger than those used in most pedal-assisted machines. Saying that the presence of pedals, the conventional bicycle style seat and relatively compact size make it relatively accessible. Hefty motorcycle style forks and brakes inspire confidence, and are welcome given the speeds the Stealth can hit. Unlike top-level e-mountain bikes the motor is in the rear hub rather than integrated into the frame and pedals, though you can switch between a nifty two-speed gear mechanism on the pedal axle by knocking your heel against a metal switch. The hub motor configuration is easier to integrate into the powertrain but the weight of the motor in the back wheel compromises suspension performance.

The design of the Stealth’s frame means plenty of standover to accommodate riders of a wide range of sizes. You can also adjust the height of the bicycle style saddle with a simple quick-release, and there’s some adjustment fore and aft if you break out the Allen keys. A conventional bicycle style handlebar stem also means you can change your riding position relatively easily there, though we’d be cautious about using bicycle components on a machine as heavy and powerful as this. Because you’re using the motor more than the pedals sizing is less critical than it would be on a regular e-mountain bike and most adults should be able to ride the Stealth without too much difficulty.

The Stealth is smaller and lighter than a typical off-road motorcycle, be that petrol or electric powered. So, it’s a little easier to transport and manoeuvre. In size terms it’s also little bigger than an e-mountain bike, so can get along similarly twisty off-road trails, assuming you can find any that you’re legally permitted to ride on. But it’s too heavy to sling in the boot of your car or put on a conventional bike rack to take it anywhere, and the fact you can’t ride it on the road or on public paths, means unless you have a van or a pick-up you’ll struggle to move it anywhere.

Given it will easily hit nearly 40mph we were pleased to see proper motorbike brakes on the F-37, these powerful enough to slow it down when required. The performance of the motor takes some getting used to, though. Unlike e-mountain bikes the electrical assistance doesn’t automatically kick in when you start pedalling – instead you have a motorbike style twist throttle that’s totally independent. So, you can get going without turning the pedals, though the weight means it runs out of puff quite quickly. Give it a few pedal strokes and the speeds suddenly increase, the Stealth really taking off and easily maintaining 25mph or more even on uphill gradients. With a peak output nearly 10 times that of equivalent e-mountain bikes the motor has real grunt as well and, even with the pedals, the F-37 feels more like a motorbike than not. A safety system meanwhile cuts the motor when you touch the brake lever, which we found a little annoying when trying technical terrain with a hand covering the brakes. Maximum range in the lightest of the three power modes just over 37 miles, though if you go flat out everywhere in ‘Competition’ you’ll find that reduces significantly.

Alongside the performance the 49kg weight of the Stealth dominates the riding experience. This is at least double that of a full-power, big terrain e-mountain bike like a Specialized Turbo Kenevo and means you batter through terrain on the F-37 rather than flow over it popping jumps and hops. That would be OK if the suspension was up to the job. True, the forks have some adjustment and you can buy different springs to suit your weight or riding style but, for all the claimed suspension travel, the Stealth never felt especially settled when clattering over roots or other bumpy terrain. That aforementioned Specialized might not be as fast or powerful but it’s similar money, the suspension will feel much more capable on a wider range of terrain and, yet again, we come back to the point you’d be able to ride it anywhere you’d take a conventional mountain bike.

While the battery is pretty hefty it should cost less than £1 to charge it plugged into your domestic electricity supply, so fuelling the Stealth is both quick and cheap. The other components shouldn’t take too much looking after, and the simple drivetrain with its single cogs front and back will require a lot less upkeep than the expensive and fragile mountain-bike style gears on an equivalent off-road e-bike.

We only had a quick go on the Stealth so can’t comment on its long-term reliability. We would say the hardware in terms of the motors, battery, brakes, wheels, tyres, suspension and gearing is all relatively proven kit (albeit calibrated in-house by Stealth where necessary) if perhaps not as widely supported as the more mainstream bits on equivalent e-mountain bikes.

Stealth is an Australian brand and well established but the mish-mash of Chinese-sourced parts, in-house components and combination of bicycle and motorbike bits could prove difficult to service if anything goes wrong. Saying that Stealth does at least have an official importer in the shape of Worthing based Ride and Glide, so you do have a point of contact if anything does go wrong.

Aside from brakes by respected Italian brand Formula we didn’t recognise many of the other components on the Stealth, the Fastace suspension forks and rear shock lacking the cachet of fancier Fox or RockShox equivalents seen on more mainstream e-mountain bikes. Wheels and tyres are basically heavyweight mountain bike kit, the cranks also bicycle grade which concerned us slightly given the weight and performance. A small digital display on the frame meanwhile gives you a speed readout, battery status and other information and Stealth offers optional mudguards if you reckon you’ll be needing them.

In isolation the Stealth F-37 is a cool looking machine, with speed to put a huge grin on your face. But in the cold light of day the limitations of where you can actually use it relegate it to little more than an expensive novelty, while the quality of the design, build and componentry simply doesn’t compare to that of the big-name e-mountain bikes you could have for similar money. True, they’re nothing like as fast. But the fact you can ride them anywhere, they’re supported by big brands and can be serviced and repaired at any competent bike shop just makes them feel a much more sensible purchase.