NuVinci Bike Transmission

With a simple twist of the wrist, the promotional materials read, you can shift this bike in a way that’s “as easy as adjusting the volume on a radio.”

As bike-industry marketing speak goes, the “radio” analogy was about as weird as I’d seen. But this month, while riding a new bike from Jamis called the Commuter 4, I could see the connection.

The shifting on this city bike does not involve traditional gears. Instead, something called the NuVinci N360 transmission adds and subtracts resistance as you pedal for power and speed.

As the company explains it, the NuVinci N360, which is made by Fallbrook Technologies, is neither a derailleur system nor an internally-geared drivetrain. It is a unique system that uses a set of large ball bearings inside a rear-wheel hub.

No gear cassette is required to “change gears.” Instead the internal bearings rotate off each other in various configurations as you turn a shift knob on the handlebars to give a range of pedal power.

It sounds strange. But in use the NuVinci system is about as easy as adjusting the aforementioned radio dial. On the handlebars of bikes like the Jamis, you control the transmission with a rubbery grip — twist one way for more power, or twist back to “downshift” into an easier setting for a hill.

There is no clicking or ratcheting of gears. The shifting is seamless and micro-adjustable — you can dial in an exact amount of resistance for the road ahead, be it flat, inclined, or going down.

A huge range of represented gearing comes with the NuVinci N360. At the high end the range is equivalent to about a 50-tooth chainring up front and a 12-tooth cog on back. That setup is powerful enough to blast to 30mph on flat land if you can push the resistance.

Further intrigue: To reveal your transmission setting, a small animated icon of a cyclist on a hill sits in a display window near the shifter. You glance down at the little cyclist to see how steep his animated hill is, and that corresponds with the NuVinci system’s setting.

Overall, the transmission setup takes some getting used to. For people who have always pedaled with gears, the “infinite adjustment” of the NuVinci system can be odd. It’s touchy, too: A subtle twist of the shift grip can dramatically change resistance from too easy to too hard.

I am not ditching my regular gears anytime soon, especially on my race bikes. The NuVinci is a heavy hub and not ideal for the rigors of off-road riding. But for a city bike like the Jamis it is an interesting and low-fuss option. “As easy as a radio dial.” I can see that now.

–Stephen Regenold is founder and editor of www.gearjunkie.com. Connect with Regenold at Facebook.com/TheGearJunkie or on Twitter via@TheGearJunkie.

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3 Comments

  1. Dan

    I have owned this bike for about three months now and have had a lot of problems with it.

    The first problem was that the rear fender rattles an insane amount. Seriously, for a $950 bike, you’d assume this kind of thing wouldn’t be a problem. But no, it was bad. Every crack in the pavement would trigger a couple seconds of rattling. It sounded like I was blasting Morse code over a loud speaker. People would turn and look at me when I rode by, as if to see what kind of junker would make such awful rattling.

    The shop that sold me the bike couldn’t figure out exactly what was causing it, but eventually I did. The clasp that holds the fender, directly below the seat, is not a solid connection. After several attempted fixes, I finally got it to stop by slipping in a two sided velcro strip between the clasp and fender and then wrapping it around itself on both sides of the mount.

    The other problems I am now having are much more serious and have made the bike almost unusable. It started when I was riding up hill and putting load on the pedal. There was a sudden slippage, which almost wiped me out. Luckily I was on a bike trail and not in the road, or I might have veered into traffic. After regaining my balance, my first thought was that the chain must have snapped, but it hadn’t. It wasn’t dislodged or anything either. The bike seemed to work fine. Skip ahead about a week and it happens again. About this time, I also noticed that it was harder to pedal on the right side than on the left side. I chalked it up to being tired, but it got worse and worse every ride. I had a friend try it out just to be sure and he immediately noticed it too. So, I brought it into the shop and they got in contact with the vendor. They opened up the hub and cleaned it out. When I got it back, I seemed more balanced, but I was unable to shift into a high ‘gear’. Now, on level ground, there is almost zero resistance. I might as well have bought $100 special at Walmart. This bike has been nothing but a huge waste of time and money. I’m currently waiting for a replacement hub, but at this point, I’d just as soon have my money back.

    If anyone has any insight into the cause of these issues, please let me know. The shop mechanics don’t seem to have a clue and there is very little information about any problems online.

    Reply
  2. gold

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  3. MrE_CVT

    New transmission CVT design by BitRaptor. Is a continuously variable transmission CVT gear only (the only one functional in the world), very compact and lightweight, and which could replace the current systems both for efficiency, simplicity and not least the costs.

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    In the web page you will find more explanations, drawings and a short video of a basic prototype.
    http://www.bitraptor.com/en_edyson_CVT.html

    The first prototype will be ready for tests during this year.

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    Reply

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