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If you were designing an electric bike from scratch, you would have an electric motor in the rear hub, and a generator in the bottom bracket, and a battery somewhere unobtrusive. You would not have a chain.
With modern electronics, it’s perfectly possible to design a generator which will reproduce the mechanical resistance you would find while pedalling a bicycle in the right gear for the conditions. It should also be possible to adjust the level of effort demanded electronically, via a control on the handlebars.
Dispensing with the chain, chainrings, chainguard, gears etc would be a significant weight saving and reduce manufacturing costs and maintenance commitments. Also, with an elctric motor in the rear hub, it should be possible to recover some energy through regenerative braking.
I guess this is the bike you are thinking of http://www.inodasveje.com/products/electronics/bike-2-0/.
For long time in my project I thought that I would make the bike just as you describes it. But after talking to different experts I decided to keep the chain. They all said that it would be possible to do it, but there would be a large amount of energy loss from the generator to the electric motor. As much as 20-25%. And with the a well kept chain this energy loss is only 3-4%.
I also talked to the designer of the Bike 2.0, who told me that the bike is only a concept and that they didn’t know if it was at all feasible.
What I have read about regenerativ braking, there is very little energy braking a bicycle compared to a car. And the problem is that of this small amount of energy only 10% return to the battery (http://www.ecospeed.com/regenbraking.pdf).
I agree with you that it would be great to have a chainless bike, but I wanted to make a realistic project and not another bike with hubless wheels!
Well… A chainless bike is just a scooter… Right?
This design would not be efficient for inputing human power. There’s nothing wrong with a standard hub motor that has a freewheel with gears, and normal bike chain. The rider can input instant power with 98% efficiency. The motor/controller/battery system is only about 80% efficiency for each stage.
The apparently pressure-sensitive and gesture-sensitive handlebar controls are lovely. The suspension mechanism seems quite novel as well. All in all, a beautiful creation.
@ Ross – Suspension mechanism? It didn’t look like it had suspension to me.
- Is there a reason for the single-sided fork? Seems like it’d be more expensive to produce that way.
- It appears the chaincase/box is the only connection to the rear wheel. In the exploded view, it doesn’t seem likely that it’s beefy enough to deal with the forces it would encounter. Am I missing something?
In fairness, I’ve owned a couple of motorcycles with single-sided rear suspension. However, that was a design that came from endurance racing, where easily and quickly changing a rear wheel was worth the trade-off of increased weight. Unless there’s a compelling reason to go single-sided, I’m inclined to view it as styling.
Again, the “closed chain box” seems to be little more than an old-fashioned full-enclosure chain guard beefed up to compensate for the lack of seat-stays. This, again, seems to be a styling feature. It also looks like you’d have to undo a dozen bolts to get at the chain if maintenance or adjustment was required.
The “icon” battery ring not only stands out visually; it stands out physically too. It looks very easy to break off if the bike is dropped or crashed.
The primary reason for the single-sided front and rear is style. I wanted the bike to stand out in the crowd.
The second reason easy maintenance. It’s easy for the user to change tires or tubes.
I’m not a engineer myself, but those that I have talked to about the project tells me that it should be strong enough. But it will be a bit heavier than a normal rear end.
But then you get a closed chain box, that makes sure there is no water or dirt getting onto the chain. There’s also a automatic chain tensioner (like the arm on a rear derailleur). This means that you very rarely need to undo the bolts on the rear/chain box.
Thank you Ross.
But as Matt says the bike is rigid, front and rear.
Cannondale called. They want Penderson to stop copying them.
@ Will – I was thinking the same thing I decide to be charitable since there are only so many reasonable configurations though…
They haven’t called yet Will!
Could you tell me what Cannondale bike it is I’ve copied? I don’t think they have the patent on single sided forks or rear. But maybe I’m wrong there?
It’s called the onBike. I’ve ridden one, it’s surprisingly stiff laterally.
…and that On bike is an evolution of the Cannondale Jackknife, which was another student design.
Yeah, I can see that there are some similarities, with the single sided front and rear.
As a design student graduating in the States this year I’m simply amazed how many students projects simply involve CAD of the design. CAD is great, but you learn much more about the design when producing a physical prototype. Get your hands dirty people, make it to see if it really works!
Hello to all of you. First of all I must say that the design it’s very nice. I’m from Buenos Aires Argentina (can you tell where it is without google?) were bikes stills being conventional. Sometimes I think cars will fly before we have bicycles like this available in stores.
I’m thinking about my own design for electric trike or bike, and I belive battery racks should be inside frame, more or less like in celular phones.
“The primary reason for the single-sided front and rear is style.”
Please do not ever make a major engineering decision for this reason again. You will have a longer and more successful career as an industrial designer and will be much more respected by your colleagues. Design schools around the world have been summarily unable to teach this lesson to their students, which is why so many of them have to learn it on the job. Save yourself the trouble and commit to it now. I say this often here, but if you want to make design decisions primarily on the basis of style you should work in fashion, as there are thousands of jobs available there compared to the handfull in the bike industry. You’ll enjoy the work much more if your primary concern is aligned with the primary goals of your projects.
I like that some thought went into keeping the battery weight low on the bike, but I’m not sure what existing or near-future battery technology could easily and efficiently be made into this donut form. Personally I’d put the battery just over the BB to help with weight distribution, though putting it directly over the back hub will help a little with the inherent structural weakness of a single unsupported chainstay. Keep in mind that adding weight over the rear axle limits the potential cargo capacity on the rear, as there is a limit to how much weight you can put over the back wheel without compromising handling. @Wilson, putting batteries inside the tubes always seems like a great idea, but it’s tough to do without making the wiring a pain in the butt or compromising the structural integrity of the tube.
I’m skeptical about the rear hub. With a drive system and a disc brake on one side it seems like you’re going to have some bad combination of heel clearance issues, unacceptable Q factor, and very high dish on a wheel that has to take electric drive torque. Maybe it all works out, but I’d like to see a prototype with realistic dimensions for all of the elements back there.
As usual, less CAD time and more build time would have benefitted this project immensely. I never understand why people bother with elaborately detailed renderings of concept ideas, it’s not like color and lighting and exploded diagrams of fictional components help the person who does the real design work once the concept moves toward production. Prototypes, people!
You are right that the only reason for a major engineering decision should not be style. But I do think the designer should challenge the engineering aspect sometimes. And I do think that the decision to make it single sided helps with making the bike different from a normal bike and causes it to stand out. Which was one of my primary goals.
And no I should not be a fashion designer!
I’ve sugested the use of 18650 batteries for my bike. There should be room for 30 batteries in the ‘donut’. According to the battery specialist I’ve asked the amps of the 18650 should reach 4.0 (2.6 today) in the next 5-8 years. And that should be more than enough to assists the user more than 50 kilometers.
A prototype would have been nice. But sadly I did not have money or time to make one. And I had to show something at my presentation, that is why I made these renderings.
The nearest I came to a prototype was this model: http://dl.dropbox.com/u/3476017/Torque%20model.jpg
Nothing in this design represents an insurmountable engineering problem unless you want it at a very low price point. Single sided hubs are all over the place, and I can see no problem fitting standard lithium ion batteries into the donut.
The only thing I would do differently as an engineer is move the bearings from inside of the rear hub to in the chainstay and have a rigid axle connected to the hub shell. That way the disc brake can be moved outboard, and the rear wheel can be a little more balanced.
@Mike, luckily I never’d consider a render for my project / prototype. As a spanish speaker maybe I was not clear about my point of batteries. What I wanted to mean is that inside the frame there is a lot of free space available, inside the tube or in a box fixed to it. Hope now it’s clear.
By the time I only have scrachts and ideas taken from different models I’ve seen on Internet. Money for me it’s a big trouble to get tools, machines and parts to build. When I could I’ll buy old bikes to get parts from.
I think it’s unfair to accuse the designer of copying the Cannondale jacknife. I’m sure it’s not the first time that kind of design has been used to support the rear wheel. Some motorcycles have been designed that way for decades, albeit with the rear ‘swingarm’ sprung rather than fixed. My Vespa has a similar setup, and is definitely not derived from endurance racing!
I have been working on a folding bike design which (if it ever sees the light of day) has a very similar method of supporting the rear wheel, without seat stays. In my case it is essential to the function of the bike, rather than aesthetic, but I came to it completely independently before I was even aware of the Cannondale design.
I am a little depressed by Mike’s dismissive rantings but I have to agree with him on the Q-factor and heel clearance thing. It does seem unlikely that you’ll get a strong enough structure AND a disc brake AND half a rear hub into the space between the bike’s centreline and the clearance for the RH pedal, and still have the wheel sitting centrally. Though you could have the rear ‘swingarm’ thing curving along its length.
I guess Mike had higher expectations when it comes to researching an idea before you spend hours working on the rendering.
I think these days, a render is much easier to achieve than engineering research and calculation. A lot of bikes are designed straight int 3d CAD packages which lend themselves to very easy renderings. It looks like the bike above was rendered directly from Solidworks or ProEngineer.
When I was in research, the lab’s director would always say, “You’re not the first person to do this. If you haven’t found a previous attempt on your idea you haven’t looked hard enough. What you need to focus on is why the previous attempts failed and what’s different now that will enable your solution.” Since then I always look at these industrial designs as missing that critical explanation of what’s different now that will enable design success where similar attempts previously failed.
The shape of the swing arm is limited by the fact that it has to enclose the chain, which absent some really goofy mechanicals has to run parallel to the centerline of the bike.
I may come off as pretty negative, but I’m not any tougher on these guys than the people who they would need to convince to spend money on their idea would be. If they’re not getting this level of critique from their instructors they should ask for a refund of their tuition.
I agree with Mike on this. Brutal design reviews were common and expected when I was in school. Hell, they’re common and expected now that I do proposal work. Everyone gets offended when someone tries to shoot down their work, but that’s the way things are, and getting hurt over it won’t help you. Also know that you won’t win over everyone in the room. Sometimes a good review is simply one where you had a reasonable reason for each reasonable question, and let the zingers go by with a “I’ll look into that for my next revision” or something along those lines.
“You’re not the first person to do this. If you haven’t found a previous attempt on your idea you haven’t looked hard enough. What you need to focus on is why the previous attempts failed and what’s different now that will enable your solution”
One of the best things I have read in a long time! It describes very concisely why good research is so important.
Electric bikes want ever be a big thing in europe. People younger than 50 dont want to ride at only 25 kmh. I’am midt forty and don’t consitter my self to be in very god shape, But still only do below 25 kmh for about 35 meters. The rest of the time the e-drive wouldt be ded weight. If it’s to be a succes it nets to help me op hill and head wind. An that’s not at 25 kmh. Slower than 30 kmh and i go in the car. They also increased the fines for doing more than 30/45 on mopet, So now we got to old cars!!!
I’m happy than in Argentina we have no limit on bicycle speed limit. I know to or three cases of guys that modified 2 sotroke 80cc motors for bikes and goes near 60km/h. I wonder how they brake. By the way, helmets are not popular.
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Hi, Do you know what is Centric Motor System with Linear Signal Torque Sensing Mode for pedelec? Though Panasonic is Centric Motor System but it is Pulse Signal Torque Sensing Mode only, while other common one is Front or Rear Motor System with Pulse Signal Speed Sensing Mode.
I thing it is not worthy to discuss a new electric bikes if they have price tag more than 700-800 euro and some “easy” version/model for the emerging markets priced at 450-500 euro.
I would like anybody to understand that only a certain % of the people will buy electric bike just because it is green. The majority will buy only if they have decent ROI.
Anything else is just a “look how nice renderings I have here”…
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