Dyname 4.0

Rocky Mountain Dyname 4.0 is unlike anything else on the trail. Where Bosch, Shimano and Specialized bolt their motor concentrically around the bottom bracket, Rocky Mountain offsets theirs above it and drives the chain via a separate sprocket, using a second tension-reading sprocket as the torque sensor. On Velomotion's dyno it produced a measured 573 W of peak power and a measured 198 Nm of peak torque at the wheel — well clear of Rocky's own 108 Nm crank claim, because that 198 Nm is the figure after the motor's own reduction stage. It returned 183 W at a steady 100 W rider input.

That offset layout gives the motor an unusually direct, sporty feel, but it asks for commitment. Velomotion's verdict is blunt: "If you put little power into the crank, you will also get little power back." It rewards riders who like to pedal hard and punishes lazy spinning. The flip side is a beautifully natural, controllable power band and genuinely quiet running, helped by a lower motor rpm and the deletion of the old upper chain slider.

Rocky Mountain quotes 108 Nm of crank torque and a 700 W peak at 85 rpm (BikeRadar launch figure) from a unit that is 18.5% lighter than the Dyname 3.0, paired with a 720 Wh battery plus an optional 314 Wh Overtime range extender. Note the variant: the current Dyname S4 Pro on bikes.com is now quoted at up to 1000 W and 350% support (region-restricted), so the 700 W / 108 Nm headline belongs to the launch-era full-power 4.0 on the 2022–25 Altitude and Instinct Powerplay. It is a specialist's drive: a poor fit for effortless summit-bagging, superb for an engaged, athletic rider.