Anyone riding a NuVinci Thorn yet?

[Danneaux]

Hi All,

I see from a review of Thorn's Facebook entries that a NuVinci N360 hub was being considered as an option about a year ago (18 Oct 2010).  At that time, testing was underway.  2 Feb 2011 saw this update:

The NuVinci N360 hub is now here and available to buy or have fitted to a rim or a bike:We will have info on the hub as it relates to fitting to our bikes, but not yet, brochures take some time to edit. In the meantime the situation is that you can purchase ANY of our Thorn models (except the tandems) that are normally equipped with a Rohloff hub with a NuVinci hub instead for a reduction in... price of £500.00

Still not a catalog item at present.  Anyone tried one?  Any word on how it works, or the expected date of release for a Thorn build on general offer?

For those unfamiliar with the NuVinci N360, more info is available from their company website here:
http://www.fallbrooktech.com/

Best,

Dan.

[Danneaux]

NuVinci has a gear-inch comparison chart showing the range and ratios of the N360 compared to Shimano's Alfine/Nexus 8, Alfine 11, Rohloff, a derailleur compact road double, and a mountain triple derailleur setup.  Plainly, the NuVinci N360 does not have the overall range of the Rohloff, but the steps between "gears" are apparently infinite (as it comprises a CVT, or continuously variable transmission, with what appears to be an essentially "stepless" shifter with push-pull cables).  I think if the chainring and cog sizes were adjusted to give the lowest reasonable low, the upper range might still be viable for the loaded cyclist who was willing to only coast downhill as a tradeoff for the low gearing needed to climb them.

Clicking on the jpg of the comparison chart at...
http://www.fallbrooktech.com/08_bike_specs.asp#gearinch
...opens up a PDF showing the same chart in a larger size.  

Nice presentation of the principles behind the mech here:
http://www.fallbrooktech.com/NuVinci.asp

Bicycle applications page here:
http://www.fallbrooktech.com/08_Bicycle_home.asp

Interesting stuff, and now more viable given the third-generation N360's smaller size and reduced weight over earlier versions.  NuVinci claim permanent lubrication of the hub mechanism, so no need for flushings and oil changes.  There is a user serviceable/replaceable external freewheel.  

Thoughts?

Best,

Dan.

[L]

I bought a NuVinci hub from Thorns earlier this year. My local bike man installed in on my Swallows W?Bike. I am delighted with it. As I live in the Fens, the only hill is the 'Lincolnshire Hill', ie the wind, but that can make a difference of 10mph. (I'm sure you all know this, a case of 'teaching Grandma to suck eggs?'
Although I coped with the Scottish and Pennine hills riding home from John 0'Groats, I cannot keep up with my husband on his solo. I wonder if it would be worth (and possible) to add another two front rings and have a derailleur for them. I keep meaning to contact Robin to pick his brains on this but haven't got round to it yet. If it is possible, then I think this would be the best possible option.
Does anyone have any thoughts on this?

[Danneaux]

Hi L,

Depending on whether your Swallow's dropout has a derailleur hanger (or horizontal dropouts to take a bolt-on hanger of the add-on variety), it might be possible to make a NuVinci hybrid, as it is in principle with nearly any internally-geared hub.  What you would need is some sort of chain tensioner, a second chainring, and a shifter.  

Where the NuVinci is continuously variable, you wouldn't have to set it up as either a half-step or wide-range double; what I would do is pick chainrings that put the lowest of the low range and highest of the highs where you want them.  Yes, there would be overlap in the range, but you could consider one chainring your "headwind" 'ring the other your "tailwind" option.  Compared to an IGH, most of the maintenance issues with a derailleur system come from the exposed cogs in the cassette and the rear derailleur.  In this case, you'd only be adding a rear chain tensioner to the NuVinci's existing single cog.  Everything else in the NuVinci (including the working fluid that acts as a pseudo-solid in shear/compression) is sealed.

Another, perhaps more elegant solution would be to replace the crankset and bottom bracket with a 2-speed Schlumpf drive, described here:
http://www.schlumpf.ch/hp/schlumpf/antriebe_engl.htm

This would dispense with any need for chain tensioners or extra chainrings and simply add another internal mech.

Hope this helps,

Dan.  

[L]

Hi Dan
Thank you for that advice, very helpful.
I already have a rear chain tensioner to take up the slack on the chain. I still have the derailleur items from before I had my bike modified.
I will return and let you know if I ever get it done.
L

[macspud]

It's an interesting concept, the input/output ratio range is a bit limited but could be overcome. I can't find anything about the over all efficiency of the hub though, does anyone know?

[Danneaux]

Ah, macspud, that is the million-dollar question!

A careful scouring of the Fallbrook website (makers of the NuVinci hub) fails to reveal any hard data on the subject.  

A Fallbrook-issued PDF ( http://www.fallbrooktech.com/NuVinci_Experience.pdf ) refers not to "mechanical efficiency" but the results of their "Fallbrook Experiment" showing increased ..."overall 'ride' efficiency" based on such factors as always being in the right gear and not having to suffer ride-delaying events like having the chain fall off (!) and the "...associated noise and clatter" of derailleur systems (!!).

The hubstripping blog ( http://hubstripping.wordpress.com/atc-nuvinci/ ) has an interesting section and videos on the intricacies of NuVinci N360 setup and the comments section mentions difficulty obtaining information on efficiency from Fallbrook.  It seems the company continues to refer to positive "rider experiences" and "the total smooth riding experience" rather than hard data wrt efficiency.  Rider reviews only allude to the apparent "lack of slippage", but these are impressions, not empirical data and in no way reflect any objective measure of overall efficiency.

Fallbrook maintain a NuVinci forum here:
http://nuvinci.informe.com/forum/

Also of note to L, the previous correspondent:  It seems there is also a range of "acceptable" gearing combinations with the N360 in order to avoid subjecting the mechanism to excessive torque loads, just as there is with Rohloff.  Chainring-to-sprocket ratios can apparently go as low as 2.0, according to their literature.  Yes, it would be best to give Robin a ring as to the particulars or float a quick check with the membership of the NuVinci forum before attempting a hybrid-drive setup to tackle the windy Fens.    

The hubstripping blog mentioned above provides a wealth of information, covering a wide variety of topics related to IGH, including a flywheel KERS attached to a NuVinci hub (though how such a small mass spinning at such low RPM could provide much assistance is beyond me), a downtube-mounted Rohloff shifter, and brifters for the Alfine/Nexus.  You can see it all here:
http://hubstripping.wordpress.com/

Best,

Dan.

[macspud]

Hi Dan,
Thanks for the additional info, I suspect that the efficiency isn't all that great, if it were I think data would be easy found. Maybe I'm being too suspicious?
I'll have into it further and see what I can find out.
Cheers,
Mac.

[L]

I have been onto the NuVinci forum as suggested by Dan and accessed 'Can I get the gearing I want'. It seems that I can add a larger ring if I want to. Many thanks for that link. I will read the other posts as well with interest.
L