The Mando Footloose NO-CHAIN Bike

The Mando Footloose NO-CHAIN folding bike has two power circuits linked by a battery. On the first circuit you pedal gently but have no direct connection to the rear, driving wheel. Instead you pedal a generator, which charges a lipo battery. The battery in turn drives the second circuit, which consists of itself for power and the motor in the rear wheel, plus its associated electronics of a throttle and some sensing mechanism which increases output up hills. It weighs 48 pounds...

Click this link for photos and more info: http://www.bbc.com/autos/story/20140...eaks-the-chain

It's a goodlooking bike, properly developed, but the question does arise of what level of losses once can expect in this two stage process. Generators and batteries are simply not that efficient at storing and releasing power.. *What do you reckon, Jeff, around a third gone in unavoidable losses?

Andre Jute

Andre Jute wrote:
The Mando Footloose NO-CHAIN folding bike has two power circuits
linked by a battery. On the first circuit you pedal gently but have
no direct connection to the rear, driving wheel. Instead you pedal a
generator, which charges a lipo battery. The battery in turn drives
the second circuit, which consists of itself for power and the motor
in the rear wheel, plus its associated electronics of a throttle and
some sensing mechanism which increases output up hills. It weighs 48
pounds...

Click this link for photos and more info:
http://www.bbc.com/autos/story/20140...eaks-the-chain


It's a goodlooking bike, properly developed, but the question does
arise of what level of losses once can expect in this two stage
process. Generators and batteries are simply not that efficient at
storing and releasing power. What do you reckon, Jeff, around a
third gone in unavoidable losses?


1/3rd sounds about right. Li-Ion can have around 85% charge discharge
efficiency and then there are the generator and the motor losses.
Electronics can keep things well above 95% if designed right.

However, quote "Range is 18 miles on full charge, or 28mi with pedal
charging along the way, and the Footloose is good for a top speed of
15mph". That would get me stranded and utterly bored. Plus you can buy a
very nice MTB for $4k and that's way more fun.

--
Regards, Joerg

http://www.analogconsultants.com/

On Sat, 27 Sep 2014 23:26:47 -0700 (PDT), Andre Jute
wrote:

What do you reckon, Jeff, around a third gone in unavoidable losses?

http://www.mandofootloose.com/eng/product/spec.asp

Methinks the efficiency would be much lower than 67%.

I tried to decode exactly what type of alternator is being used. All
I know is "dual winding" which I guess(tm) means it has only two
"gears". The motor is probably optimized for flat terrain, at only
two possible speeds, which can't be a very efficient compromise
between torque, power, speed, and motor efficiency. Some speed
control can be provided by the DC to AC inverter, but only with some
additional losses. The "dual windings" should help here. I attempted
to mix that into my AC motor efficiency numbers, but without motor
data, it's a really bad guess(tm).

Minimum Maximum
Eff % Eff %
Pedal DC generator 75 90
Charger & control 80 95
LiIon Battery 80 85
DC to AC inverter 90 95
AC motor 50 80

Multiplying the efficiencies together, I get 22% to 55% drive train
efficiency. By comparison, the drive train efficiency of the common
gear and chain system runs between 85% and 96%[1].

The implications of having a 250 watt drive train system, running at
about 50% efficiency is that half the input power is wasted as heat.
If it were actually running at full 250 watt power, an equal amount of
heat would need to be dissipated somewhere. In effect, it's an
electric moped of sorts, where the bulk of the power to the ground is
delivered by the LiIon battery, and the pedals are just an auxiliary
power source to give the rider some exercise.


[1] Tech Journal of the IHPVA #52 Summer 2001.
The mechanical efficiency of bicycle detailer and hub-gear
transmissions by Chester R. Kyle, Ph.D., Frank Berto

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sunday, September 28, 2014 7:17:27 PM UTC+1, Jeff Liebermann wrote:
On Sat, 27 Sep 2014 23:26:47 -0700 (PDT), Andre Jute

wrote:



What do you reckon, Jeff, around a third gone in unavoidable losses?



http://www.mandofootloose.com/eng/product/spec.asp



Methinks the efficiency would be much lower than 67%.



I tried to decode exactly what type of alternator is being used. All

I know is "dual winding" which I guess(tm) means it has only two

"gears". The motor is probably optimized for flat terrain, at only

two possible speeds, which can't be a very efficient compromise

between torque, power, speed, and motor efficiency. Some speed

control can be provided by the DC to AC inverter, but only with some

additional losses. The "dual windings" should help here. I attempted

to mix that into my AC motor efficiency numbers, but without motor

data, it's a really bad guess(tm).



Minimum Maximum

Eff % Eff %

Pedal DC generator 75 90

Charger & control 80 95

LiIon Battery 80 85

DC to AC inverter 90 95

AC motor 50 80



Multiplying the efficiencies together, I get 22% to 55% drive train

efficiency. By comparison, the drive train efficiency of the common

gear and chain system runs between 85% and 96%[1].



The implications of having a 250 watt drive train system, running at

about 50% efficiency is that half the input power is wasted as heat.

If it were actually running at full 250 watt power, an equal amount of

heat would need to be dissipated somewhere. In effect, it's an

electric moped of sorts, where the bulk of the power to the ground is

delivered by the LiIon battery, and the pedals are just an auxiliary

power source to give the rider some exercise.





[1] Tech Journal of the IHPVA #52 Summer 2001.

The mechanical efficiency of bicycle detailer and hub-gear

transmissions by Chester R. Kyle, Ph.D., Frank Berto



--

Jeff Liebermann

150 Felker St #D http://www.LearnByDestroying.com

Santa Cruz CA 95060 http://802.11junk.com

Skype: JeffLiebermann AE6KS 831-336-2558

55% maximum efficiency essentially makes it a trendy feel-good gimmick for the sort of lifestylers who like to claim they're saving the earth, rather than a bicycle for getting places. 22% efficiency would be a joke.

The electric motor on my Kranich is rated 250w peak output; everyone knows it is underrated to take advantage of the law. But when I had a power meter on loan, I calculated that, even with the pedelec limiter at 25kph/15mph removed (which I don't do because there's no point), in a sprint, without the electric bike rider pedaling, your local club racer would very likely leave it behind. Of course, on a longer course the electric motor would "win" because it doesn't run out of steam while the battery is good.

Thanks for the numbers.

Andre Jute

On 29/09/14 04:17, Jeff Liebermann wrote:
On Sat, 27 Sep 2014 23:26:47 -0700 (PDT), Andre Jute
wrote:

What do you reckon, Jeff, around a third gone in unavoidable losses?

http://www.mandofootloose.com/eng/product/spec.asp

Methinks the efficiency would be much lower than 67%.

I tried to decode exactly what type of alternator is being used. All
I know is "dual winding" which I guess(tm) means it has only two
"gears". The motor is probably optimized for flat terrain, at only
two possible speeds, which can't be a very efficient compromise
between torque, power, speed, and motor efficiency. Some speed
control can be provided by the DC to AC inverter, but only with some
additional losses. The "dual windings" should help here. I attempted
to mix that into my AC motor efficiency numbers, but without motor
data, it's a really bad guess(tm).

Minimum Maximum
Eff % Eff %
Pedal DC generator 75 90
Charger & control 80 95
LiIon Battery 80 85
DC to AC inverter 90 95
AC motor 50 80

Multiplying the efficiencies together, I get 22% to 55% drive train
efficiency. By comparison, the drive train efficiency of the common
gear and chain system runs between 85% and 96%[1].

The implications of having a 250 watt drive train system, running at
about 50% efficiency is that half the input power is wasted as heat.
If it were actually running at full 250 watt power, an equal amount of
heat would need to be dissipated somewhere. In effect, it's an
electric moped of sorts, where the bulk of the power to the ground is
delivered by the LiIon battery, and the pedals are just an auxiliary
power source to give the rider some exercise.


[1] Tech Journal of the IHPVA #52 Summer 2001.
The mechanical efficiency of bicycle detailer and hub-gear
transmissions by Chester R. Kyle, Ph.D., Frank Berto


Looks about right.

The only thing I'd suggest is that, if the designer was smart, they'd
make it a tricycle, so you could sit and pedal while stopped at the
lights. No point having a rest while there are all those watts to waste
in power electronics!

--
JS

On Sun, 28 Sep 2014 14:08:54 -0700 (PDT), Andre Jute
wrote:

On Sunday, September 28, 2014 7:17:27 PM UTC+1, Jeff Liebermann wrote:

Minimum Maximum

Eff % Eff %
Pedal DC generator 75 90
Charger & control 80 95
LiIon Battery 80 85
DC to AC inverter 90 95
AC motor 50 80

Multiplying the efficiencies together, I get 22% to 55% drive train
efficiency. By comparison, the drive train efficiency of the common
gear and chain system runs between 85% and 96%[1].

[1] Tech Journal of the IHPVA #52 Summer 2001.
The mechanical efficiency of bicycle detailer and hub-gear
transmissions by Chester R. Kyle, Ph.D., Frank Berto

The above article can be found at:
http://www.ihpva.org/HParchive/PDF/hp52-2001.pdf

55% maximum efficiency essentially makes it a trendy feel-good
gimmick for the sort of lifestylers who like to claim they're
saving the earth, rather than a bicycle for getting places.
22% efficiency would be a joke.

Yep. Let's pretend that every part of the drive train system is 95%
efficient. Except under ideal conditions, on flat ground, and
optimized for one speed, that's unlikely. However, it's fun to play
with the numbers. That would be 0.95^5 for overall efficiency or
0.77%. Still not even close to the 85% to 96% of a conventional
bicycle.

It's not the efficiency of each component that seems to be the
problem. It's the number of components involved. I don't know any
way to eliminate any of these components, so I suspect this machine is
stuck with the lousy efficiency.

I intentionally left out dynamic braking. On hills, that would be a
good idea and will certainly help with the efficiency. However, with
only two "gears" (or speeds), methinks the bicycle was designed for
flat ground, where dynamic braking is not so beneficial.

Thanks for the numbers.

Reminder... they're mostly guesswork on my part scraped from web
sites, books, articles, notes, experience, and pure guesswork.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Mon, 29 Sep 2014 07:55:43 +1000, James
wrote:

The only thing I'd suggest is that, if the designer was smart, they'd
make it a tricycle, so you could sit and pedal while stopped at the
lights. No point having a rest while there are all those watts to waste
in power electronics!

That presents an interesting problem. Presumably, the crank powered
generator is operated at one specific RPM to maximize its efficiency.
This could easily be one of the strangest rides in cycling, where the
crank rotation is NOT coordinated with the speed of the bicycle. I'm
not sure I could ride such a machine.

This claims that it has "artificial intelligence gear shift":
http://www.mandofootloose.com/eng/product/technology.asp
"The system automatically changes gears by detecting slopes".
Gears? What gears? I guess(tm) that would be the "dual winding
motor".

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Monday, September 29, 2014 12:05:30 AM UTC+1, Jeff Liebermann wrote:

This claims that it has "artificial intelligence gear shift":

http://www.mandofootloose.com/eng/product/technology.asp

"The system automatically changes gears by detecting slopes".

Gears? What gears? I guess(tm) that would be the "dual winding

motor".

I haven't actually made the effort to understand it's current stage of development, but there is a torque sensor in some Japanese, and presumably in the Bosch and Panasonic, mid-mount motors, necessary for "clutching" gearshifts. The reason I haven't looked into it is that I have zero, zilch, nada intention of buying either a gearbox or a motor that requires a custom frame, so I'll stick to the good-value bottom-bracket-fitting Chinese motors if and when I do buy a midmotor, together with my ultra-reliable rear-mount Rohloff hub gears. But the Chinese don't yet have a reliable torque controller, so they fake it up in the software.

So this "two-speed" could be nothing more than a torque- or inclinometer-controlled electronic permission to use more current on hills. To sell the bike as a pedelec, they have to limit the speed anyway to 25kph, so there are already circuits in place.

Andre Jute