Nuvinci is all the rage lately, and it seems to be a good solution to dealing with fat tires that tend to rub the chain in the lower gears as well as the incessant chain jumps & breakage that comes with shifting a mid-drive under load. Two weeks ago Fallbrook (Nuvinci) announced the release of a new N330 CVT hub which will be cheaper than the street price $365 N360 and have slightly less ‘shifting’ range (330% vs 360%). It should integrate with the Harmony electric shifting system which will automatically keep the pedal cadence at a constant speed. This unit should be available in limited supply mid 2015.

Avail mid 2015 shown with new manual C3 ‘shifter’.

It’s also coming with a new C3 manual shifting controller, and it looks like it will be hard to ‘retrofit’ the Harmony autoshift system on many DIY ebikes. Expect the warranty to cover it mounted on 250 watt mid-drives and under although it could probably take a bit more than that without breaking. If you want to mate the N330 with a BBS02 at a full power 750 watts expect it to fail in pretty short order. If you want a CVT that will handle 120Nm/7hp you might want to try to grab a discontinued 5-year-old-but-still-brand-new N171. They are about 3 lbs heavier than the N360 but can take twice the force.

I found the Wikipedia page for Nuvinci pretty fascinating, did you know the traction fluid is works with elastohydrodynamic lubrication?

When this fluid undergoes high contact pressures under rolling contact between the two very hard elements, the spheres and the discs, the fluid undergoes a near-instantaneous phase transition to an elastic solid.

Wow, who would have guessed. Sounds like that traction fluid would make a lousy lubricant for pretty much anything else (you have a sick mind).

Thanks to Lorrin Lee who thinks that smaller balls should mean a lighter ‘package’, but knows that isn’t always the case.