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How does the efficiency of this drive system compare to a simple chain drive? I would expect some loss, but I am curious how much.
“How does the efficiency of this drive system compare to a simple chain drive?”
See the research of Andreas Fuchs:
Also, in the Proceedings of the 4th Velomobile Seminar:
チェーンのない折り畳み式電動自転車 | Mando Footloose : monogocoro ものごころ
Mando Footloose chainless hybrid bike generates electricity as you pedal | Eco Chunk
Will – As an designer/engineer when I 1st saw this new hybrid e-bike technology I had concerns about the efficiency – we all know direct chain drives are efficient. We also know that mechanical energy being converted to electrical energy to charge a battery (chemical energy), and then back into mechanical (via a 2-speed motor) loses some energy.
BUT … when I first rode a crude test rig, I discovered the real benefits of this chainless hybrid system. It is a very effective plug-in battery powered e-bike….Plus…. the addition of an alternator gives control and generates power. This feels completely intuitive and user friendly – you can use and generate as much ..or.. as little power as you choose.
Still sceptical ? …. Think of the system as chain driven…But… with an infinity long elastic chain, which can store pedalling energy, for release when you choose…. with control of of both: the elasticity, and the release of the stored energy. Add to this, regenerative braking which also ‘stretches the elastic’ when slowing – rather than loosing it ….. you get the idea….
Miles – Good links – yes this technology has some solid background.
Personal note: as a bit of a bike mechanic, it was so weird to see adjustments made buy the Mando R&D guys plugging in a laptop to adjust gearing
Thanks for the ‘plug’ James
I love the idea, and you make a pretty strong endorsement, regardless of efficiency losses… So I can’t wait to try one. In a way, I guess it’s a modern take on early mopeds – in the sense that it’s a powered two wheeled vehicle with semi-vestigial human power. Tracing that parallel development arc indicates we’re going to see some pretty exciting and minimal electric-only two wheeled vehicles in the next decade.
Regardless, do we get to know how heavy it is? I’m no weight-weenie, but when it’s a folding bike that you’re expected to take with you, it’s a pretty relevant question.
Yes skeptical and was just at the factory that makes Stridas now, odd bit of timing. Let’s see this being ridden and test results of the drivetrain efficiency. That’ll do more to impress then plugs for yet another cad fantasy bike on design blogs and please more than beer coaster calculations.
No CAD concept that just raises expectations … this is real !!
Re-efficiency … Best see the comments below and especially by Dr. Andreas Fuchs – who is leading expert on ‘electronic bikes’ … and also 4 page report in Bike Europe: http://issuu.com/mark77a/docs/bike_europe_october__12__compressed_
I just got back after launch in Korea, and the Production bike is very impressive – Seoul is VERY hilly (think San Francisco – compressed in to a downtown area) .. so 1st thing I did was head out up these hills .. and did a few hill starts .. No problem! the dual wound motor works a treat even better than concept demonstrators.
There are about 50 early footloose’s riding about Seoul and several of the test riders/ambassadors turned up to the launch. What was so cool for me to see was as they parked up, a technician hooked up a laptop to each bike and updated the ECU software – the riders went off much happier…. a modern version of ‘spannering’
A few more pic’s from Seoul, just added >> https://plus.google.com/photos/105398075724946531166/albums/5783148738897695585?banner=pwa
and at last (for such a wired country) a website: http://www.mandofootloose.com
Mark (a tad jet lagged …. my excuse for lousy spelling)
As a design blog, this report surprisingly lacks depth and fails to dissect the tremendous design implications the electronic drivetrain has brought forth. This is one of the rare cases that I found some random commentators on Bikeforums offering a more intelligent discussion on bike design than this blog:
Assuming Mando does not bungle the product management and marketing, a revolution in e-bike design is afoot. I hope a more rigorous follow-up report is forthcoming?
Frank, I have been really busy with work lately, so yes… the majority of recent posts have been quickly written general overviews. Intelligent discussion is is what this comment section is for though, so I am glad to see additional information and links from Miles, Mark, and even from you.
Everyone, feel free to add thoughts and opinions here if you think something is lacking in the original post.
The discussion is just beginning here….The thread you linked to was started 3 weeks ago!
WRT the efficiency of the pedal input, it doesn’t seem particularly relevant to compare it to a singlespeed, perfectly maintained, chain drive. A better comparison would be with the Nu Vinci CVT which probably has an average efficiency of less than 85%.
A few more links:
Just wanted to make it clear that I love this blog and really appreciate James’ posts. To continue the discussion, I believe that Footloose signifies a disruption in e-bike design guidelines. The old adages—such as power transmission efficiency—that are inalienable for HPVs should be reexamined and in certain cases deprioritized.
Take the electronic drivetrain for example. The blue ocean customers would not care so much about “efficiency.” It’s a foreign concept to them, and they’d charge the battery anyway. They are likely to appreciate, on the other hand, the benefits of such a system: persistent pedaling cadence/force regardless of terrain, adjustable/memorized control and output curves for different riding conditions, use it indoor as a fitness equipment, less moving parts, and so on.
Hopefully, the design will enable you to move the bike with the wheels on the ground when it is folded. It would be too heavy for most people to conveniently pick up.
How much low-stress bicycle infrastructure that Seoul has would be a big determinate of how many potential users there would be for the bike.
“Hopefully, the design will enable you to move the bike with the wheels on the ground when it is folded.”
Ok, for more in-depth discussion 😉 I will try to help break down the efficiency question with some rough ‘beer-coaster calculations':
I spoke with the South Korean head engineer at the Eurobike and he told me some figures, and those figures correspond with what I also read here: http://ebikeee.com/en/2012/09/03/mando-footlose-the-future-of-the-ebikes/ So this is presumably the standard data that Mando gives about the Footloose and I will base my calculations on that. (apologies in advance; I do my calculations in metric system, as should you 😉
Max distance without pedalling 30km on 36V 8.2Ah (=295Wh). I used this tool: http://www.hembrow.eu/personal/kreuzotter/espeed.htm for calculating needed W riding at 25km/h for 72kg person, sitting up straight, no wind: 188W. So for riding 30km at 25km/h you need 225Wh. Rough estimation efficiency of motor system: 225/295 -> 76%
(kind of makes sense, compared to other way to calculate: battery discharge efficiency X motor controller efficiency X motor efficiency 0.95×0.95×0.85=76%)
Now with pedalling you add 10-15km to the range. So lets take best case scenario: 45km total. For this you will need to add 112.5Wh to the battery in 1h48m (45km at 25km/h). An average person riding a normal bike at 19km/h will exert 100W. So lets say you also need to put in a 100W pedalling power in the Mando to get 15km extra range. Rough estimation of the charge efficiency would then be: 112.5W/180W -> 62.5%
(kind of makes sense, compared to other way to calculate: Generator efficiency X battery charge efficiency 0.85×0.75=64%)
Now to estimate the complete drivetrain efficiency: 62.5% x 76% -> 47.5%
This would explain why you couldn’t ride the Mando without battery power.
Bare in mind the setting of these calculations: ‘Done in a pub on beer coaster!’
To put calculations in perspective:
If the 30km range claim includes many start- stops -> efficiency goes up
If the 30km range claim is not at 25km/h but at lower speed -> efficiency goes down
If the added range is 10km instead of 15km -> efficiency goes down
If effective battery capacity is lower -> efficiency goes up
If 20″ wheels use so much more power than the 28″ wheels used for bicycle power calculations -> Electric efficiency goes up (but overall remains the same, the loss isjust in a different place of the bike)
“Now to estimate the complete drivetrain efficiency: 62.5% x 76% -> 47.5%”
That sounds about right : )
I don’t think the wheel size would make a significant difference to energy use – unless you were on rough or soft terrain.
I suspect there are reasons other than the efficiency which preclude the ability to pedal it once you have discharged the battery to its limit……
Is there anything known about the 2-speed motor? I recall that MBI in Korea were developing a retro-direct 2-speed bicycle hub motor (similar thing to the new SRAM unit)….
I’m glad someone took interest in this.
I thought of separate generator pedals rather than drive pedals for a bike vehicle in my contest entry to this site. I imagine my idea’s now patented in Asia?
” I imagine my idea’s now patented in Asia?”
The general principle has been the subject of public discussion for more than 20 years.
Bicycle of the Future | Cosmic Revolutions
Motor running => current goes into motor
Wheel and Motor standing => current goes into battery
While riding: no battery losses for the generator current
Generator – DC-circuit/Battery: Efficiency dependant on size, weight, cost of generator and on type of power electronics. Efficiency roughly 80 to 90+ percent
Do you think this is low? Then measure efficiency of a multi speed internal hub or of a menchanical CVT and check your beliefs! (70+ to 90+ percent for internal gear hubs)
DC-circuit/battery – motor: Like in an e-bike, e-moped or e-scooter: 80 to 90+ percent
Since motor is a little bit bigger than on an e-bike, motor efficiency is higher than in e-bikes. In addition, since Efficiency = (1 – Power_Loss/Power_Transmitted), the efficiency of the motor is very high because the motor transmits BOTH current from the battery AND current from the generator. The ratio of Power_Loss/Power_Transmitted is lower, that is, motor efficiency is better than in standard e-bikes with hub motors.
So efficiency of a series hybrid is not 0.8*0.8=0.64, it is better:
And then an other effect comes in: In e-bikes, electric power is assist_factor*human power. Since the assist factor is usually inbetween 1 and 2, the series hybrid e-bike will be among the more efficient e-bikes because for electricity, it has simply the most efficient drive train.
Conclusion: The series hybrid might not be an ideal touring e-bike. But it might be very good in many other e-bike applications.
Andreas Fuchs, Berne, Switzerland
Another series hybrid being developed:
Of course there is nothing to prevent a belt or a chain being added to this design (perhaps a tweak here and there) between pedals and rear wheel. The generator could then also be the motor and leave off the now superfluous hub motor, gaining bike transmission efficiencies losing weight and doubling range. Next, an aerodynamic inflatable fairing, motion activated lighting, handlebar dashboard, and so on bingo.
Interview with Mark Sanders in DEVELOP3D:
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I have 3 simple questions:
1. When will it be available?
2. Where will it be available?
3. How much will it cost?
Jack, the test market will launch in South Korea very soon and the bike is scheduled to be available in Europe sometime in 2013. I don’t know about pricing, but I’ll see if Mark can answer that.
10 months ago I inquired about when where and how much. I have still not received a response.
Jack, I suggest that you contact the company directly at http://www.mandofootloose.com/eng/support/contactus.asp
How much. when and where can i get one !!
Tony, I am not sure about the price, but as I mentioned to Jack above, I’ll see what I can find out.
Bicicleta eléctrica sem correia transforma pedaladas em energia (com FOTOS) | Green Savers
Looks like a great product!
According to MK newspaper, in korean, European price is about 3200 euros. In Korea, it is available from mid November 2012. They have opened a dedicated shop “Cafe Footloose’ in Seoul just recently
Thanks for the pricing info, Peter!
For those of you who are interested, the Footloose website is now up and running, though most of the detailed info is only in Korean at this point. According to a tweet from Mark Sanders, details in English are coming soon.
Please keep the price range somewhere below USD700 then you can move a lot of this bike. I love it and was desperate enough to visit the homepage everyday and even sent an email to firstname.lastname@example.org.
If it is sold for $3200 then I would buy the second gen (or when this version get old). If it is around $700 I will order 1 and get my friends buy 2-3 more.
I love the design. I am curious about the cables. As a wire hater – you name power lines, supposedly wireless speakers etc I noticed that the promo shots above the wires have disappeared. I think you would do well to either group them so they are wrapped in a sheath similar to what you get at a speaker shop or route them internally. Even better get rid of them!
Johnny – I agree !! I am on the case … (persuading the makers to make the bike naked or at least wireless
As the lithium battery is built-in, when it dies, how does one replace it?
There is a battery door (inside/wheel side of rear ‘Beam’).
6 screws, DIY potentially. But Battery Management / balancing systems are mush improved these days to maximise life – expect 7-10years plus a al Tesla, and then only gradually reduced range (or in this case reservoir).
Where can I buy a Footloose Mando electric ebike where can I get one and how much do they cost please contact me Bruce E Johnson at email@example.com I am a handicap I can’t drive a car but I ride my bicycle 35 miles minimum per week this would be great for me
test the mando footloose, now available in Berlin at “Platoon Kunsthalle”
how long before it comes out in the UK?
Toni, you might want to contact Mando directly at http://www.mandofootloose.com/eng/support/contactus.asp
Cool Stuff: Mando Footloose | xraydelta