One of the primary purposes of an e-bike is transferring power from the motor to the drivetrain to "support" your regular pedal stroke. All of the different drive units do this in relatively the same way, although subtle differences in their power output make them all feel slightly different. It is important to note that all of these systems work pretty well; the differences between them are relatively subtle but noticeable. We tested this metric primarily based on feel, as opposed to any sort of scientific measurement, and our testers could all notice the differences between the various models. All of the e-bikes we tested have several support modes offering varying levels of pedal assist support.

A carbon frame shaves off several hundred grams of weight, of course. However, this is largely irrelevant when it comes to eMTBing. The two major advantages of carbon on eMTBs are, on the one hand, greater freedom in optimising the frame design and, on the other hand, increased stiffness. Thanks to carbon, smooth transitions can be achieved, better facilitating the integration of motor and battery. Unfortunately, the magical black material also has a few potential disadvantages. Carbon has poorer thermal conductivity, which means that heat is dissipated less efficiently with a fully integrated motor, and stiffer is not necessarily always better. Frames and wheels require a certain amount of flex to be comfortable and to generate enough traction through curves. Buying a carbon eMTB can currently only be justified by aesthetics rather than functionality.
It wasn't all gold stars for the Bulls, however, as the larger battery storage of this bike makes it the heaviest in our test. This heavyweight rig is far from nimble or agile, giving it a more one-dimensional performance on the descents, and hampering its climbing abilities in technical sections or tight corners. Its charging port is also recessed into the frame making it one of the least user-friendly, and while we did like their e-bike controls, they couldn't quite match the ergonomics or display of some of the competition. Overall, we had a blast riding the E-Stream EVO AM 4, read on to find out how it compares.

Testers found the Rocky Mountain Instinct Powerplay to perform relatively well on the climbs. The steep seat tube made for a comfortable climbing position and the powerful pedal-assist drive unit felt dialed. Its traction could be improved with beefier tires, and the weight of the bike feels centered a little higher than the competition resulting in some awkward handling at lower speeds. The Giant Trance E+ is also a competent climber, with ground-hugging Maestro suspension, comfortable geometry, and plenty of power on tap when you need it. The YT Decoy CF Pro has plenty of power, but it seems clear that this bike was designed for the descents. The Decoy still climbs relatively well, but testers found the low bottom bracket height made it more prone to pedal strikes than other competitors. Our least favorite bike on the climbs was the Ghost Hybride SL AMR. The Ghost has solid geometry numbers, but the pedal assistance felt less powerful and was definitely less consistent than the competition.
E-bikes mostly use motors and battery options from a few major suppliers: Bosch, Yamaha, Shimano, and Brose. A few other brands exist, but are less reliable or powerful. Some, like the Yamaha system, have more torque, and others, like Bosch’s Active Line, are nearly silent. But, generally, all four make good options. Look for motor output (in torque), which will give you an idea of total power. Just like car engines, more torque equals more power off the line and more boost to your pedaling. But watt hours (Wh) is perhaps a more important figure to use—it takes into account battery output and life to give a more accurate reflection of power (higher Wh equals bigger range).
What's The Best Electric Mountain Bike?