Autobike keeps your pedaling cadence in its sweet spot
The Autobike Evolution at Interbike 2013
One of the things that keeps some people from cycling more often is the gears – although they need the gears to manage hills and headwinds, they're never sure which one they should be in. If that sounds like you, then you might like the Autobike. It shifts gears automatically based on the rider's cadence, and manages to do so without a battery.
Instead of a battery, the Autobike has an SRAM Dynamo front hub. This uses the spinning motion of the front wheel to generate electricity, which in turn powers the bike's electronics and gear-changing servo motor. The electronics measure the rider's cadence via a number of sensors, and activate the motor to automatically shift the bike to a higher or lower gear in order to maintain that rhythm.
Also included in the electronics package is an accelerometer, that can detect when the bike starts going up an incline. When that happens, a lower gear is preemptively selected.
Because the Autobike has a continuously-variable Nuvinci N360 rear hub transmission, the rider won't notice any kind of transition between gears – in fact, technically-speaking, they'd be better described simply as drive ratios.
Not everyone wants to pedal at the same rate, however, so users can chose between three pedaling speed ranges. This can be done using either a set of buttons mounted on the down tube, or wirelessly via a smartphone app.
The Autobike is currently available in two commuter-style models, the Voyage and Voyage ST, which sell for US$1,000. A hybrid model, the Evolution, is due to be out soon.
There's more information in the video below.
UPDATE (Sept. 22/13): One of the Autobike's creators has informed us that the three pedaling speed buttons are actually used to adjust the cadence in 5 rpm increments (up or down) per push, allowing the rider to maintain a cadence anywhere from 30 to over 100 rpm.
About the Author
An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.
All articles by Ben Coxworth
Gears are there to keep the desired cadence. Selecting the cadence is more important than selecting gears...great innovation, except there are only three selectable cadences with step-less gears? Step-less cadence should only be a step away!
Nice to see the Nuvinci being used in an end application, the application seems to suit the mechanism.
Would also be good if the rider was able to infinitely select whichever pedalling speed (cadence) they prefer for a given situation rather than only having 3 to choose from (the 3 ranges may be user customisable, but the article didn't go that far, if not, why not) because that is effectively limiting the system to discrete gear ratios again.
Perfect for the market it's aimed at, though I doubt I'd feel happy on a bike with such high bars and a seat that far back and would more likely choose the Breezer Beltway.
Interestingly for a bike whose pitch is one that isn't about technology, and more about the ride, you can pair an Android device to it but what can't these days.
Sadly I couldn't figure out the lowest gear (in inches) that it'll effectively go so I wonder how suitable it'd be for a place like Devon. However the NuVinci has a 360% range* so could one assume that a 26-94 inch range be plausible? I read elsewhere that it has a range of 30-120 rpm cadence.
Fullbroook have an interesting pitch with 'a full 360 range' as it's implying that you couldn't go any higher than 360% - my Audax bike has a 434% range - still it's very good and exactly what the market needs.
Using the AutoBike Android or iOS app (via a bluetooth connection to the bike), you can adjust the desired cadence in 1 rpm increments anywhere from 30 to 100+ rpm. Using the buttons on the bike will adjust the target up or down in 5 rpm increments (anything smaller than 5 rpm is tough to even detect) over the same range.
While Ben demo'd the bike, we made adjustments using the app so we didn't get into the details of the bike-mounted buttons.
Just wanted to point that out since I probably neglected to mention it but it's an important point as the commenters noted. :)
The Evolution is currently spec'd for 34-122 gear inches (45T/20T) and the Voyage/Voyage ST for 28-99 gear inches (38T/20T). Either can be changed but we've found these to be the favorite settings after getting many test riders on each bike. Our next app release will also enable someone to change these values to match any sprocket changes they make post-purchase.
The reason we added the ability to pair the app with a smart phone is because we already do all the computing in the background and all that was needed was the bluetooth system on chip and a little C coding. While not required to use/enjoy the bike, the benefits are possibly avoiding the purchase of a cycle computer, being able to tune/tweak the bike post-purchase, sharing riding experiences with friends, diagnostic/troubleshooting help, and remote firmware/feature updates. We also use it extensively during development as well as in the final testing phase of the bike building process. Plus it's flat-out cool! :)
Sounds very effective! I wonder how much spare capacity the dynamo has to run front/rear lights for night riding? Most countries have mandatory lighting requirements these days, if you go for a ride near dusk you need safety for the home journey anyway. I presume people would be able to amend the bars and (hopefully) seat position for personal comfort?
I had the AutoBike Classic, that was a 6 speed auto shifting derailleur system from many years back. It had weights on the rear wheel spokes that shifted radially with speed, causing the rear 6 speed derailleur to shift up and down automatically.
I thought the system was pretty neat, I learned how to control it easily enough however not everybody who tried it had the same success.
It was a completely useless gimmick, of course. A decent set of index shifters are so simple and intuitive to use that automatic shifting, frankly speaking, has no practical application.
That is not the shift pattern that anyone uses manually. It also has to respond to torque as well, raising the cadence for higher efforts, but not in direct proportion. The accelerometer helps, but the system needs to know when one is almost coasting, but turning the cranks for blood circulation. Fast pedal boats are remarkable good at matching torque to cadence with no gear changing, just hull resistance.
The "Brains" can make gear changes several times/second, independent of the rider's actions, while pedaling or not. The rider can coast, accelerate or decelerate, and the bike will maintain the proper gear ratio needed for the chosen cadence. I've yet to see an indexing shifter that can function at that rate, have as many gear choices or be that intuitive.
Seriously, no built-in lights? Considered hub brakes?
With all the settings, it just seems like another way to shift gears in terms of the user wondering what cadence is right all the time.
Done with all the clutter on the handle bars. Done with all the wires. Done with all the cogs down below.
Will the system evolve to be adaptable as standard to all bikes, just as the automatic gear-shift in cars?
In short, is this the future of cycling?
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