DRIVE UNIT DUST-UP!

It's Shimano vs Bosch vs Brose vs Yamaha in the battle of the full-power motors

- Alex Evans

While brands are experimenting with all kinds of different motors on the latest 'lightweight' e-bikes, most 'full-fat' models use a drive unit from one of the big four manufacturers - Bosch, Brose. Shimano or Yamaha. But which is best? The table overleaf shows how they measure up on paper, but to really put them to the test, we hit the trails, hard, on bikes equipped with all four systems.

POWER STRUGGLE

Bosch's Performance Line CX feels like the most powerful motor here, despite nominally providing less support (340 per cent, versus 400 per cent or more), especially in its eMTB and Turbo modes. The assistance it provides is addictive, constant and feels as though it matches and augments your pedalling inputs with total cohesion. The harder you pedal, the more the motor works. Support doesn't tail off with increases in cadence or power (if speeds remain below the cut-off limit), and you're never left feeling that you want more assistance that the Bosch is refusing to provide. Tackling climbs is a truly pleasurable experience, where you can either cruise at a lower speed and put in significantly less effort, or pedal with vigour, expending more energy but getting to the top much quicker.

In contrast, the Shimano STEPS EP8(00) feels as if it offers less assistance than the Bosch in its top Boost mode. At times, it seems like it throttles back on power, especially when you pedal harder on steeper or faster ascents. This can be frustrating when you're expecting the motor to back up the effort you're putting through the pedals. It's not slow or underpowered, but getting the most from it requires lower pedalling cadences. As you pedal faster or harder, it reduces its assistance on what feels like a sliding scale.