I'm thinking of buying new bike next year, most probably combo for exercise & commuting in summer. Since terrain is relatively hilly here and both fixed city-bike and casual combo with 3x7 gears making me too much tired, I thought of buying as additional item NuVinci Mondo hub. Reviews are mostly positive but I'd like to read real pro and contra, not paid-by-manufacturer-or-reseller review. Do I win anything real for that price? Or is this just money waste? What are maintenance costs and issues?
Are you talking about adding a NuVinci to a conventional derailleur-geared setup? That won't work.
The NuVinci itself is very heavy, expensive, less efficient than derailleur gears, and doesn't offer as wide a range of gears as a wide-spaced derailleur-geared setup. The only advantages that I can think of is that you've got one shift lever instead of two (not a big selling point IMO), and you've got continuous variability so you don't need to hunt for the right ratio.
I dont really grasp percentage ratios in relation to gear ratios,I prefer talking in gear inches so my nuvinchi N360 set up is 42t chainring 16t sprocket 700c wheel.
The gear calculator on Sheldon brown website shows my gear inches range as 36" bottom to 130" top,this is an excellent spread of gear ratios.Also note it has no duplication of gears like you find on a double chainring or worse still a triple chainset,a larger rear sprocket will give a lower set of ratios if needed for hilly areas.
The hub is heavy and would not be a good addition to a full suspension bike,the weight is not noticeable in a hardtail frame.
The unit is sealed and maintenance free if your not really able or into tinkering with bikes and adjusting front/rear derailleur setups thats a big bonus.
You're never out of gear and can change down equal to 2 or 3 gears stationary useful for less experienced riders,there is no issue with chainline and the thicker chain you can use has a long life.
The N360 has the retro fit option of harmony automatic electric shifting I am using this and it works really well, great for commuting bikes and again people who get a bit fuddled with 21+ gear systems.
Yes in pure efficiency terms the derailleur is more efficient but in real world use the smooth jerk free and if wanted automatic shifting ability of the Nuvinch N360 more than offset this and I wont be using derailleur gears by choice again anytime soon.
They are an excellent combo with crank drive e bikes but work fine on normal bikes too. The harmony autoshifter means that to remove a wheel you just unplug the power lead from shifter unit mounted on the wheel and remove from bike, it has no cables to disconnect maintain or adjust for that matter.
The NuVinci system is fantastic in principle and one day all bikes might come with it, but we aren't there yet. As the system stands there are a few matters that might not make it the answer to your prayers of an easier time going up hills:
To conclude, you will have extra weight, lower efficiency and a reduced range of gears. Despite the benefits of CVT with smoother shifting, reduced maintenance and not having to match your cadence to available gears, you are not going to get round the fundamentals of weight/efficiency/range.
My recommendation is that you try an electric assist bike such as one of the models made by Giant. Although they weigh a lot they are amazingly nimble and you can pedal as much as you want to on one.