Ellesworth to be first to market a variable transmission gearing system.

[Steveb]

It's not on an MTB though, it's going on a new range of cruisers, with no derailleurs or fixed-gear internal hub but with "advanced infinitely variable transmission technologies." The NuVinci hub offer "continuously variable planetary (CVP)" transmission. The tech is not bike specific but the NuVinci owner, Fallbrook Technologies Inc., reckons it will "change the way the world builds machines that use transmissions."

Ellesworth has licenced the technology for a new line of leisure bikes to be launced in 2006. Ellsworth will purchase the hubs from Aftermarket Technology Corp. (ATC), Fallbrook’s licensed manufacturing partner.

Amongst all the usual industy hype was such claims that the new hub will offer "a true alternative to conventional derailleur and fixed-gear internal hubs,". The PR went on:

"It offers the bicycle rider incredibly smooth, simplified shifting while pedaling, coasting, or at a standstill. It delivers all the advantages of planetary gearsets without the limitations of fixed speed ratio, without wide gaps between gears, and without jarring or shocking shifts typical of conventional drivetrains. NuVinci technology is dependable, compact, whisper-quiet, and completely sealed for protection from weather, dirt and abuse".

Honda have proven that a variable transmission has a place in the MTB world, if only they could make it a bit cheaper (rumours of c.$20k per bike were about when it first appeared). Prices on the Nuvinci are as yet unknown, as are it's compatabilities with the harsh world of MTB's, but the fact that it's about to enter the cycle world is a step in the right direction.

[timH]

hmmmmm, okay....

http://www.fallbrooktech.com/images/new_cvt_diag.jpg (http://www.fallbrooktech.com/)

[thetrailbuilder]

is there not a better explaination of how it works, diagrame not too clear

[timH]

Click the link and see what you make of the description on their site.

[thetrailbuilder]

watched a vid there on the website got a general idea of how it works, but theres no sound on this uni computer, so i never heard the comentry

[Steveb]

This from Velo Vision Interbike report in Dec 2004:

FALLBROOK
This is an interesting one! Fallbrook are a general engineering
consultancy in the field of variable speed drives – that is, drives where you vary the ratio smoothly, without steps as is usual with geared systems. They’d come to Interbike with a neat ‘NuVinci’ bicycle hub unit, still under development, but looking quite intriguing. Pity about the hype: “The first true paradigm shift in cycling for 50 years!” Right...

Range is 400%: in other words, the high gear is four times bigger than the lowest. This compares well with the 300% or so range of
the current crop of 8-speeds, but is well under the Rohloff’s 514% – which matches the range of a touring derailleur system.

They do say that the price is intended to be more Shimano than Rohloff, and this could be realistic: it does seem to use fewer
moving parts than a multi-gear hub.

I leave it as an exercise for the reader to examine the cut-away model of the hub internals (pictured) and to figure out how it works. A clue is that the ‘sun’ rotates freely on bearings. Because the hub uses hardened steel-on-steel rolling contact, rather than V-belts or the like, it should have good efficiency and, if well-built, durability too.

Unfortunately, novel cycle transmissions don’t have a great record in financial durability – but I do wish them luck, and hope to see them around with a finished product in a few years.

It's certainly very interesting, the video makes it pretty clear how it works.

[chris_the_sham]

huh huh huh huh ball axle

[dmccue]

If you gave me one of those for free I'd pass. Not only is all that extra weight onboard, the rear unsprung weight is much higher. Its been done before on motorcycles.
Yamaha's 2-Trac system uses fluid pressure to power the front wheel (in addition to the rear wheel via conventional chain drive). Fluid pressure is the way to go, not a mechanical link.