Electric Bike Action Bike Test: Bulls Copperhead EVO AM 4 Trail Bike



it’s tuned to start off immediately and give you a push. Response time feels immediate, because the torque, cadence and speed sensors are reading 1000 times per second, and that includes a virtually unnoticeable drop in power when shifting. 

The Copperhead’s front end is pretty forgiving, between the 66.5-degree head angle and the Lyrik Ultimate fork.


We do prefer e-MTB mode on most rides, but a few of the really steep climbs had us reaching for Turbo, just to keep our momentum going. The bike, with this motor, absolutely loves devouring climbs. On the previous Bosch motors, when you passed 20 mph, you could physically feel the drag of the motor while pedaling. No more. Now, when you’re pedaling through some flat ground, you don’t have to pedal harder.

Setting sag at 30 percent provided even better performance and even over some rough, rocky terrain with a few decent drops; we never bottomed it out. The combination of the Lyrik Ultimate fork and Super Deluxe RT rear shock with two tokens was spot-on. It was supple and provided excellent small-bump compliance. 

Overall ride quality on the trail is outstanding. There was nothing we threw at the Bulls that it didn’t take in stride, letting us ride faster and a little harder than our own comfort zone.

Note that the new fourth-generation CX motor has some subtly built-in cooling fins. The design looks great, too.


The two different tires chosen for this bike, though the same size, were different knobby patterns and different rubber compounds. The front tire is made for more bite, and the back tire can slide a little (on purpose). Interestingly, this combo worked really well and provided great grip and let us accurately point and go wherever we wanted to. 

The bike always felt planted with sure-footedness in corners, and it really rides great on every surface. You can run it with lower pressure for softer stuff, and the 2.8-plus-inch tires offer plenty of volume to run a bit lower pressure without much danger of pinch-flatting.


There are lower-spec, lower-priced versions of the Copperhead EVO line. The AM 1 starts at…


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