I just had a Nuvinci hub installed on my Giant Lite. It replaces the Shimano Nexus-4.
The first improvement is the added gear range. The Nexus-4 has a total range of 184%. The Nuvinci has a total range of 350% with a low end gearing of 1:0.5. This gives me a much better climbing gear for the long hills around here (1 mile up at 7-8% grade) and a hope of climbing the steep ones (12%) with my son in tow on the back. The Nexus-8 would have provided a similar improvement.
The other change is more subtle and I'm still learning how to us it. The "Continuously Variable Planetary" system allows for very fine resolution control of the gearing ratio. The controller is a twist grip. The grip will twist a full 360 degrees to go through the whole range of the hub. There are no stops or clicks on the controller - it's more like a dimmer switch that smoothly travels through the gear ratios.
I'm still experimenting with how this added resolution impacts the behaviour of the Panasonic motor and controller. As most of you know, the Panasonic controller responds to the torque sensors on the cranks. The controller limits the motor's contribution at low-torque (to limit top speed) and at high-torque (to protect the motor?). With the Nexus-4 hub, I was developing a sense of when the motor would come in at each gear.
With the Nuvinci, I can more easily find a point where I spin the cranks at a high cadence. When I dial the gearing up from that point, I can hear when the motor starts to kick in - at first just during the power stroke portion of the crank rotation. As I increase gearing further, the motor stays on throughout the crank rotation and is working more. I'm not sure I understand what the "sweet spot" is for this motor/controller.
I haven't come up with a new strategy for how to use this finer control. I think I should be able to spin the cranks with less assistance in all conditions and thus increase the effective range of the battery. I don't know by how much yet. Alternatively, I could select a gearing that makes the motor contribute at it's maximum efficiency.
I'll continue the report when I have more experience on the new configuration,
keith.
The first improvement is the added gear range. The Nexus-4 has a total range of 184%. The Nuvinci has a total range of 350% with a low end gearing of 1:0.5. This gives me a much better climbing gear for the long hills around here (1 mile up at 7-8% grade) and a hope of climbing the steep ones (12%) with my son in tow on the back. The Nexus-8 would have provided a similar improvement.
The other change is more subtle and I'm still learning how to us it. The "Continuously Variable Planetary" system allows for very fine resolution control of the gearing ratio. The controller is a twist grip. The grip will twist a full 360 degrees to go through the whole range of the hub. There are no stops or clicks on the controller - it's more like a dimmer switch that smoothly travels through the gear ratios.
I'm still experimenting with how this added resolution impacts the behaviour of the Panasonic motor and controller. As most of you know, the Panasonic controller responds to the torque sensors on the cranks. The controller limits the motor's contribution at low-torque (to limit top speed) and at high-torque (to protect the motor?). With the Nexus-4 hub, I was developing a sense of when the motor would come in at each gear.
With the Nuvinci, I can more easily find a point where I spin the cranks at a high cadence. When I dial the gearing up from that point, I can hear when the motor starts to kick in - at first just during the power stroke portion of the crank rotation. As I increase gearing further, the motor stays on throughout the crank rotation and is working more. I'm not sure I understand what the "sweet spot" is for this motor/controller.
I haven't come up with a new strategy for how to use this finer control. I think I should be able to spin the cranks with less assistance in all conditions and thus increase the effective range of the battery. I don't know by how much yet. Alternatively, I could select a gearing that makes the motor contribute at it's maximum efficiency.
I'll continue the report when I have more experience on the new configuration,
keith.