Regeneration: Is it worth it?

[Jerome Daoust]

I started collecting some thoughts, keeping things simple, to a high-
level understanding (not detailed math for given ride scenarios):
http://www.expandingknowledge.com/Jerome/Bike/Gear/Electric/Regeneration/Effectiveness/2008_08_13_Wondering/Main.htm

[deerfencer1]

JD,

As someone who initially hated the WC regen feature, then came to
tolerate it and even enjoy it on occasion until I suspected it played
a role in the premature demise of my lifepo packs, I'd say you hit the
nail on the head in regards to battery pack concern, especially on
very steep downhills where I've seen readings as high as 34A going
back into the pack(s). From a practical standpoint regen just aint
worth it IMO.

Fortunately it is fairly easy to override regen on the TFX bikes with
a little throttle action, but e+ got it right IMO by letting the rider
choose the regen level (or eliminate it entirely) via the bike console/
computer. Rakesh may well have gotten the idea for this improvement
right here on the TF boards as we published a wish list many moons ago
for whomever was taking over production of these bikes after Wavecrest
exited the business, and regen control was high up there.

LH

On Aug 13, 3:49 pm, Jerome Daoust <EyesToThe...@gmail.com> wrote:
> I started collecting some thoughts, keeping things simple, to a high-

> level understanding (not detailed math for given ride scenarios):http://www.expandingknowledge.com/Jerome/Bike/Gear/Electric/Regenerat...

[remf]

Jermome, really interesting & well thought out. Your excellent
observations & Larry's expert thoughts confirm what I've always
suspected.

Still I think the E+ regen implementation say with LiFePO4s may change
my mind.

rem

On Aug 14, 5:49 am, Jerome Daoust <EyesToThe...@gmail.com> wrote:
> I started collecting some thoughts, keeping things simple, to a high-

> level understanding (not detailed math for given ride scenarios):http://www.expandingknowledge.com/Jerome/Bike/Gear/Electric/Regenerat...

[deerfencer1]

rem,

Yah, couldn't agree with you more re the LiFePos if they are all
they're cracked up to be. I'm dying for a pack that can take regen
voltage in stride without negative consequences.

LH

[David]

Good thoughts all. I recall an earlier post about this. The
compelling information there was
about problems with laptop batteries and heat. The post talked about
studies that had shown
that recharging the batteries while running actually hurt the
chemistry of the battery and reduced
its life.

Experience of folks here on the TF or WC would support that as well,
so it would seem...

-David

> > level understanding (not detailed math for given ride scenarios):http://www.expandingknowledge.com/Jerome/Bike/Gear/Electric/Regenerat...- Hide quoted text -
>
> - Show quoted text -

[Cyclepete]

I sure hope regen doesn't have a significant effect on the battery
life. I love putting regen on when I'm going down a long hill to
control my speed. In fact, braking assist is my favorite thing about
regen. But I'm using a Bionx with a Sony Lithium Manganese battery.
Maybe that battery does better?


According to Bionx, they say the regen increases the distances you can
get 10-15%. With my 35 mile typical range in city traffic, that means
I'm getting 3-5 extra miles by regen. So that's not much. As many
people have said, regen may be more a "bug" turned into a
"feature" ( i.e., lack of freewheeling by the hub motor).

I would love a LiFePo4 battery on my bike. Not just because it can
easily handle regen but for fast charging. Imagine taking a long trip
and being able to recharge your bike while you have a cup of coffee.
This would make long-distance bicycle touring very practical with an
ebike, even if you had to stop every 35 miles or so.


BTW, regarding the 75% of braking being performed by the front wheel-
the amount of braking done by your front wheel depends on your
deceleration. The more you decelerate the more weight you transfer
from the rear wheel to the front wheel. At lower decelerations, you
actually have more braking force from your rear wheels as it is
carrying most of your weight. The fastest you can decelerate on a bike
is when you are almost going over the front bars. At this point, there
is no weight at all on the rear wheel so 100% of your braking is on
the front. It's good to practice this maneuver so you can stop as
quickly as possible in an emergency.

> > > level understanding (not detailed math for given ride scenarios):http://www.expandingknowledge.com/Jerome/Bike/Gear/Electric/Regenerat...Hide quoted text -

[jr]

Jerome,

Nice analysis. A couple of points to add:

Analysis of the case with a series of hills ignores the advantage
which may be gained without regenertation, by tucking into an
aerodynamic crouch during downhill run and using gain in kinetic
energy to ride up the next hill. Would someone with a TF try this
comparison, while measuring heart rate and watt hours?

Forcing high current into a storage device for short duration is a job
better suited to a capacitor than a battery.

-JR

On Aug 13, 1:49 pm, Jerome Daoust <EyesToThe...@gmail.com> wrote:
> I started collecting some thoughts, keeping things simple, to a high-

> level understanding (not detailed math for given ride scenarios):http://www.expandingknowledge.com/Jerome/Bike/Gear/Electric/Regenerat...

[deerfencer1]

My DrainBrain usually shows about 8% gain in pack power after a mixed
ride of hills and rolling terrain, or about a 1 Ah gain on a 12-16 Ah
pack, so yeah, nothing to write home about.

Separately, not all LiFePos can take high charging (or discharge for
that matter). In fact most of the lower priced packs are speced very
low, so be sure you know what you're buying. I plan to wait till next
spring to see how this tech matures over the next 6-9 months. Sure
seems like there ought to be more choice on the market than there is
now, given the feverish competition. I read a bit more of A123'
s IPO prospectus and they are investing very heavily in new plants
overseas, including Korea.


LH

[Fluxface]

All,
A quick fix around the dis-benefits (there are many benefits) of
regenerative or electric breaking is by adding a small (2-3amp-hr) 36V
SLA pack in parallel, at the “B” battery connection point, to the
stock front “A” hub ni-mh battery pack and also add a diode (schottky
with its inherent yet minimal 0.3V forward voltage drop) to eliminate
any re-charging current from entering the $$ pack at all (same thing
applies to lipo users). The small pack could be carried inside an
under seat bag, switch and all, with no more than a few lbs of weight
gain. A side benefit would be a lower voltage sag while hitting the
gas, thus better perceived performance.

BK

PS, yes I see the questions coming, I have all the answers but not the
time to properly address them, point being here is don’t sweat it,
this stuff is simply details.

> > > level understanding (not detailed math for given ride scenarios):http://www.expandingknowledge.com/Jerome/Bike/Gear/Electric/Regenerat...- Hide quoted text -

[Jerome Daoust]

Hi JR,

Yes, for short-duration regeneration:
a) Getting back to speed after stopping for example
b) Small down then up in the road (going under something.)
There are better solutions than trying to recharge a battery...
1) Someone mentioned capacitors. Those thinks can charge up
faster and deliver lots of power for short amount of time.
This is being used in Formula Zero (in a different way):
http://www.formulazero.nl/pagina/home/en
2) Using kinetic energy as storage.
a) That's what we can all do when letting ourselves speed up
when going down a short hill to re-use some of it for an
uphill immediatly following.
b) Formula One applications:
http://www.motorauthority.com/news/motorsport/brake-energy-regeneration-in-f1-by-2009/
3) Compressed air cars are apparently quite efficient in their
brake regeneration process:
http://en.wikipedia.org/wiki/Compressed_air_car

But none of this is really good for those long downhills, which is
where our best recovery potential lies.

Jerome

[Bike_on]

All-

Nice thread.

One point not being mentioned concerning regen is weight. It makes
perfect sense to add regen to a 3000lb hybrid car. But what about a
20lb electric bike (If one existed)? Staight roadies get their
acceleration advantage with the light weight (And good components).

As e-bikes increase their power and range, so does the weight. I
think the performance curve eventually begins to flatten out as more
of the power and energy is used to sustain high speeds rather than
increase. Secondly, a heavier bike is more like a motorcycle and less
enjoyable to pedal non-assisted.

My criteria would be somewhere around the knee of those two factors:
diminishing air drag power/speed, and pedal weight.

Practically, for me, any bike under 50lbs, 500-600W, should not
consider regen. 50-65lb and 600-800W is marginal. Over 65lb and 800W
up motors, yes, getting back the energy would be a help.

FInally, the battery type and performance is the driver on weight and
peak charge, as already noted by others.

Dan

On Aug 14, 6:23 pm, Jerome Daoust <EyesToThe...@gmail.com> wrote:
> Hi JR,
>
> Yes, for short-duration regeneration:
>    a) Getting back to speed after stopping for example
>    b) Small down then up in the road (going under something.)
> There are better solutions than trying to recharge a battery...
> 1) Someone mentioned capacitors. Those thinks can charge up
>    faster and deliver lots of power for short amount of time.
>    This is being used in Formula Zero (in a different way):
>      http://www.formulazero.nl/pagina/home/en
> 2) Using kinetic energy as storage.
>    a) That's what we can all do when letting ourselves speed up
>       when going down a short hill to re-use some of it for an
>       uphill immediatly following.
>    b) Formula One applications:

>      http://www.motorauthority.com/news/motorsport/brake-energy-regenerati...

> 3) Compressed air cars are apparently quite efficient in their
>    brake regeneration process:
>      http://en.wikipedia.org/wiki/Compressed_air_car
>
> But none of this is really good for those long downhills, which is
> where our best recovery potential lies.
>
> Jerome
>
> On Aug 14, 8:48 am, jr <j...@cloudchambers.com> wrote:
>
>
>
> > Jerome,
>
> > Nice analysis.  A couple of points to add:
>
> > Analysis of the case with a series of hills ignores the advantage
> > which may be gained without regenertation, by tucking into an
> > aerodynamic crouch during downhill run and using gain in kinetic
> > energy to ride up the next hill.  Would someone with a TF try this

> > comparison, while measuring heart rate and watt hours?- Hide quoted text -

[akallen]

All,

I would opine that there might be two scenarios here. There are many
biking enthusiasts in this forum and that form of usage might dominate
their requirements definitions for an electric bike. Correspondingly,
there is what I call the transportation viewpoint, in that electric
bikes can be a form of alternative transportation in a diminishing
fossil fuels world. I would also guess that the latter will be the
overwhelming number of riders in the future. Some of the questions
I've previously asked are along these lines of how best to design
bikes that are not recreational in nature. The metaphor might be that
many of the riders in this forum are in the Ferrari segment of
biking. What might become the growing segment (the dealers amongst us
will likely see the trends first) is the Prius of electric biking. In
that one, I would expect distance, lifespan, reliability, comfort,
etc. to dominate the bike designs. This would encourage regeneration
just as sophisticated as in a hybrid car. Charge controllers in the
solar world aren't that expensive, so one that needed to handle much
less current in the biking venue doesn't seem like an over-the-top in
ebikes that are already half the price of a car. I suppose what it
comes down to is that I'm hoping that 80% of the commute being under
25 miles becomes a mainstream target for electric vehicles of all
kinds, including the ebikes.
arlene

[deerfencer1]

Arlene,

You may be right, but the biggest barrier IMO to this whole scenario
of mass adoption of e-bikes for transportation is price, and price
will put a cap on things like range, at least until the price of
robust lithium packs comes down. IOW the "masses" are looking for--and
buying, at least recently--the $300 Walmart/Costco e-bikes, and it
only stands to reason that you're NOT going to get much of a battery
(ergo limited range) with these bargain basement rides.

I'd compare it to the cordless drill market, where you can get
homeowner grade drills and batteries that are often half the price (or
less) of the pro tools--but guess which ones last longer, have more
power and longer run time? As with most things, you often have to pay
up for quality.

The Liberty bikes that Tracy is selling are probably the closest to
your description of a good quality e-bike that is priced fairly
conservatively, and IMO Liberty is smart to offer their more popular
models with various battery options, which shows the first time
consumer exactly where a lot of the costs come in on these machines.

Long story short: batteries remain the key problem/challenge here,
pure and simple,
and the fact that many of us here have spent nearly as much (or more
in my case)
on battery packs as they have on their bikes speaks for itself.

Larry

[Bike_on]

IMHO, on alternate transportation, most people are not enthusiast, and
don't want an e-bike - they want a scooter, a cheap scooter.

I took a spin yesterday on a 2-stroke Aprilla scooter that a co-worker
got. Get's 120mpg, 50cc (no lisence) goes 45-50mph on flats, 30+ up
hills, 5 hp, Full set of lights, turn signals, peppy, fully automatic,
disk brakes, suspension, cost him $3200, gets no exercise.

How can any e-bike compete with that for the seditary American mind?
Electric motorcylces may at 4-5k.

Dan

> > arlene- Hide quoted text -

[thes...@cox.net]

Arlene,
You are very well spoken, and a very articulate writer. I always enjoy reading your posts. I must disagree with you on the regen issue.

If I read you correctly, you likened the a major growth segment of ebiking to the transportation market--practical individuals who use the bike for commuting, and as an alternative fuel vehicle for transportation, similar to the Prius market. You conclude that because a Prius has regen, that regen will also be part of that ebike segment. I disagree.

A bike is beautiful in its simplicity. I think people all over recognise this. Regen systems add weight and complexity. The more weight and complexity you add, the less bike-like it becomes, and soon you have an electric motorcycle. Not that there's anything wrong with electric motorcycles. They're just not ebikes.

The more bike-like the ebike, the more it will remind people about their childhood, and the simplicity of bike-like vehicles makes us feel like kids again. That's the ebike's tour de force.

In the very near future, we'll say "Remember when we had to have regen systems because the batteries just weren't good enough?" That day is coming rapidly.
Keith

[thesaxman]

Arlene,
I think everyone on this forum can really get behind you on the last
sentiment of your post:

"I suppose what it comes down to is that I'm hoping that 80% of the
commute being under
25 miles becomes a mainstream target for electric vehicles of all
kinds, including the ebikes."

Thanks for that unifying statement. Well spoken, indeed!
Keith

[Cyclepete]

Regen doesn't always add weight. On systems like Bionx, there's
nothing mechanically added to allow regen, just control circuits to
push excess current from the motor back to the battery. I suppose it
adds complexity to the control system, but few people have reported
any problem with this.

The issue is that, currently, you have a choice between an electric
motor that freewheels but can't do regen vs. motors that are "always
on" and so don't freewheel but can do regen. So if you run out of
power, you get more drag for human-only pedaling with a regen system
than with a freewheeling system. On heavy ebikes this probably doesn't
matter as the bike is too heavy to want to pedal without power. But on
light bikes like Bionx systems this might limit how far you'd want to
go in a human-power only mode. On light ebikes I think you'd be better
off with a freewheeling motor.

Regen adds so little to the range that I just don't think it is much
of a consideration on bicycles. Bikes are light, cars are heavy as
someone already pointed out.

Now you COULD design a clutched motor that both freewheels and
supports regen. THAT would add weight. The regen could probably barely
make up for the added weight :-)

On Aug 19, 3:04 pm, <thesax...@cox.net> wrote:
> Arlene,

[deerfencer1]

The new E+ bikes offer user-adjustable regen via the dashboard
console, but it's unclear to me if the zero regen setting allows true
freewheeling. Joe has test ridden one recently; perhaps he can
comment. I DO know Joe reported the motor is pounds lighter than the
Wavecrest and yet retains the WC's magic silence.

LH

[Tor Atle Lunde]

Is it not possible to measure the EMF(?) and cancel this force out by
applying a certain amout of power?

Tor Atle

[deerfencer1]

Yes, you can manually override regen on the WC X bikes with just a
touch of the throttle--usually a cinch, but NOT when you're descending
a very steep grade and trying to keep your hands on the brakes.

Some might ask, Why would anyone want to override regen braking in
these cases? Because steep downhills at high speeds cause the highest
voltage spikes back into the battery pack--I've seen as high as -34A
on my DrainBrain--and several of us suspect these kind of peak surges
are NOT good for pack longevity, something the WC engineers may have
overlooked. The engineers behind the e+ bike have come up with the
ideal solution IMO by allowing the rider to preselect the amount of
regen allowed.

LH

[OptOut]

Re E+ regen:
The TF style braking regen is nearly identical to how it is on the TF,
a fixed drag is activated when you apply EITHER brake. I don't know
if this can be regulated other than disabling (disconnecting) the
brake switches.
The big change is in the controller which can be used to cycle through
9 levels of regen. This is not for quick braking but can be used to
add appropriate slowing regen while going down a long hill. Or to add
light regen drag while pedaling or for training with the rear wheel up
on a trainer.
Forward power also has 9 levels. There's a 0 level for no power (aka
freewheeling). The bike can be locked into level -9 regen and the
controller can be removed to make it harder to steal and ride away.
The rear wheel is very hard to turn at that setting.

Best,
Joe (mobile)

[OptOut]

Re is regen worth it,
That question implies a balance with cost on one side and benefits the
other.
Any electric motor is also a generator so no cost there. Assume regen
will only be used in place of traditional braking and you eliminate
the "cost" of unnecessary lost energy while gaining a big benefit of
not wearing out brakes. The other benefit is converting braking energy
into useful energy.
Assuming the rest of the bike is designed well, the only true cost is
damage to currently available electric storage (the battery) caused by
high current. We here at this forum are not even 100% sure that this
is a contributing factor to our TF NiMH batteries dieing. Personally I
used REGEN A LOT and my batteries lasted over 3 years. Some day
electric energy storage technology will catch up with the requirements
of regen on bicycles. Light weight, efficient and high power in and out.

Best,
Joe (mobile)

On Aug 20, 2008, at 3:25 PM, deerfencer1 <deerf...@aol.com> wrote:

[deerfencer1]

<<Some day
electric energy storage technology will catch up with the
requirements
of regen on bicycles. Light weight, efficient and high power in and
out. >>

That's certainly the dream, Joe. Here's hoping!

The LiFePos to me look like a "bridge" technology in that they appear
to sacrifice a bit of weight and bulk in favor of longevity. I can
live with that trade-off. But in the long run of course the dream is a
10-12 lb battery pack that will give us 30-50 mile range--and be able
to accept high regen/discharge. The Optis are doing a (wise IMO) end
run around this problem by forgoing regen in favor of their range-
friendly freewheel design. Which leads me back to my belief that regen
may indeed not be worth it, at least right now.

Larry

On Aug 20, 6:12 pm, OptOut <optib...@gmail.com> wrote:
> Re is regen worth it,
> That question implies a balance with cost on one side and benefits the
> other.
> Any electric motor is also a generator so no cost there. Assume regen
> will only be used in place of traditional braking and you eliminate
> the "cost" of unnecessary lost energy while gaining a big benefit of
> not wearing out brakes. The other benefit is converting braking energy
> into useful energy.
> Assuming the rest of the bike is designed well, the only true cost is
> damage to currently available electric storage (the battery) caused by
> high current. We here at this forum are not even 100% sure that this
> is a contributing factor to our TF NiMH batteries dieing. Personally I
> used REGEN A LOT and my batteries lasted over 3 years. Some day
> electric energy storage technology will catch up with the requirements
> of regen on bicycles. Light weight, efficient and high power in and out.
>
> Best,
> Joe (mobile)
>

[OptOut]

Larry,
The opti is THE perfect case in point for arguing against regeneration.
Opti designers had to ask themselves the same question - is it worth
doing?
Regen requires a pull (backwards torque) on the motor. This can not be
done using a standard bicycle drive, especially the rear derailer. So
it would require adding another chain and drive ring hardware at the
rear wheel and bottom bracket. That's a lot of added weight and
complexity. Additionally, from a designers point of view, for every
pound of weight added you need another 2 lbs added for a stronger
frame, bigger brakes, a more powerful motor, and bigger battery.
In conclusion, both Optibike and Tidalforce/matra/emotion/bionx/etc
are optimized for their drive trains with respect to regeneration.

Best,
Joe (mobile)

[Bike_on]

On Regen Batteries:

Has anyone used NiCads with their TF? They have a low resistance than
NiMH and pretty rugged, don't mind being run low to prevent memory.
They have a lower E-density, but what's an extra 5 lbs if your bike is
already 85-90?

CAn the NiCads take a high input current better than NiNH? I think
they do.

Dan

On Aug 21, 8:58 am, OptOut <optib...@gmail.com> wrote:
> Larry,
> The opti is THE perfect case in point for arguing against regeneration.
> Opti designers had to ask themselves the same question - is it worth  
> doing?
> Regen requires a pull (backwards torque) on the motor. This can not be  
> done using a standard bicycle drive, especially the rear derailer. So  
> it would require adding another chain and drive ring hardware at the  
> rear wheel and bottom bracket. That's a lot of added weight and  
> complexity. Additionally, from a designers point of view, for every  
> pound of weight added you need another 2 lbs added for a stronger  
> frame, bigger brakes, a more powerful motor, and bigger battery.
> In conclusion, both Optibike and Tidalforce/matra/emotion/bionx/etc  
> are optimized for their drive trains with respect to regeneration.
>
> Best,
> Joe (mobile)
>

> >>>>> wrong with electric motorcycles. They're just not ebikes.- Hide quoted text -

[Bike_on]

FYI NiCad write up:

I know most will balk at the energy desity, and I by and large agree.
However, if you want a CHEAPER, rugged, high life cycle (1000-1500)
mid-range pack (<10Ahr), then it may work. For a small hub project,
say for a fun beater bike, paying $250 vs, $125 for lead-acid, would
be worth it in weight, and life cycle.

SOURCE: BAttery University

The nickel-cadmium battery

Swedish Waldmar Jungner invented the nickel-cadmium battery in 1899.
At that time, the materials were expensive compared to other battery
types available and its use was limited to special applications. In
1932, the active materials were deposited inside a porous nickel-
plated electrode and in 1947 research began on a sealed nickel-cadmium
battery.

Rather than venting, the internal gases generated during charge were
recombined. These advances led to the modern sealed nickel-cadmium
battery, which is in use today.

Nickel-cadmium prefers fast charge to slow charge and pulse charge to
DC charge. It is a strong and silent worker; hard labor poses little
problem. In fact, nickel-cadmium is the only battery type that
performs well under rigorous working conditions. All other chemistries
prefer a shallow discharge and moderate load currents.

Nickel-cadmium does not like to be pampered by sitting in chargers for
days and being used only occasionally for brief periods. A periodic
full discharge is so important that, if omitted, large crystals will
form on the cell plates (also referred to as memory) and the nickel-
cadmium will gradually lose its performance.

Among rechargeable batteries, nickel-cadmium remains a popular choice
for two-way radios, emergency medical equipment and power tools. There
is shift towards batteries with higher energy densities and less toxic
metals but alternative chemistries cannot always match the superior
durability and low cost of nickel-cadmium.

Here is a summary of the advantages and limitations of nickel-cadmium
batteries.
Advantages

Fast and simple charge, even after prolonged storage.

High number of charge/discharge cycles - if properly maintained,
nickel-cadmium provides over 1000 charge/discharge cycles.

Good load performance - nickel-cadmium allows recharging at low
temperatures.

Long shelf life - five-year storage is possible. Some priming prior to
use will be required.

Simple storage and transportation - most airfreight companies accept
nickel-cadmium without special conditions.

Good low temperature performance.

Forgiving if abused - nickel-cadmium is one of the most rugged
rechargeable batteries.

Economically priced - nickel-cadmium is lowest in terms of cost per
cycle.

Available in a wide range of sizes and performance options - most
nickel-cadmium cells are cylindrical.
Limitations

Relatively low energy density.

Memory effect - nickel-cadmium must periodically be exercised
(discharge/charge) to prevent memory.

Environmentally unfriendly - nickel-cadmium contains toxic metals.
Some countries restrict its use.

Relatively high self-discharge - needs recharging after storage

> > - Show quoted text -- Hide quoted text -

[deerfencer1]

Dan,

Justin (the fellow behind the DrainBrain) up in Canada carried Nicads
for a while and I think was happy with them for the most part.

Personally I'm dubious of the 1000+ lifecycle range claimed at BU as
the 18V Dewalt cordless line of tools uses premium Nicads and I rarely
get more than two seasons (maybe 300-400 cycles) out of a pack before
they're done--and I've been through dozens of these batteries over the
20 or so years I've been running their drills and grinders. Also,
Nicads do NOT like high temp charging, so regen may well be a no-no
with these.

LH

[Cyclepete]

A big negative is that these motors are always adding drag, even with
the regen turned off. You can't get rid of the motor's cogging effect.
The only way to eliminate it is some sort of freewheeling, which a lot
of non-regen systems use, or clutch system.

This cogging effect will slow you down when coasting downhill and also
make it more difficult to pedal with the electric motor turned off.

I'm not sure about the problem you see in the backwards torque and a
standard drive. Bionx and other hub motors mounted on the rear of a
bicycle have no trouble with this. In regen, the wheel simply appears
to have more friction than normal. It doesn't impact the drive train
any other way.

On Aug 21, 8:58 am, OptOut <optib...@gmail.com> wrote:

> Larry,
> The opti is THE perfect case in point for arguing against regeneration.
> Opti designers had to ask themselves the same question - is it worth
> doing?
> Regen requires a pull (backwards torque) on the motor. This can not be
> done using a standard bicycle drive, especially the rear derailer. So
> it would require adding another chain and drive ring hardware at the
> rear wheel and bottom bracket. That's a lot of added weight and
> complexity. Additionally, from a designers point of view, for every
> pound of weight added you need another 2 lbs added for a stronger
> frame, bigger brakes, a more powerful motor, and bigger battery.
> In conclusion, both Optibike and Tidalforce/matra/emotion/bionx/etc
> are optimized for their drive trains with respect to regeneration.
>
> Best,
> Joe (mobile)
>

[deerfencer1]

> A big negative is that these motors are always adding drag, even with
> the regen turned off. <

Pete,

Yes and no. No clutch that I know of in the WC system, yet there is no
perceptible regen drag when the throttle is engaged even just a tad,
so the throttle functions as the regen override on downhills, and
allows full speed descents with just a few watts of power. I have
gotten my S750X up well over 50 mph on steep downhills on many
occasions by bypassing regen this way (i.e. by just feathering the
throttle a tiny bit), but I think it's a no-go on the non-X bikes due
to the 20 mph speed limiting software.

I don't know how Rakesh's e+ bikes have been modified to control
regen, but apparently it CAN be completely disabled with a simple push
of a button on the console. I think the WC and e+ systems are both
sophisticated enough electronically to do this through software mods.
Maybe Rakesh can comment if he sees this.

LH