one for the theologians out there

[Peter Noris]

Is this wheel legal? all the energy is generated by the cyclist - 

"Any form of human-powered vehicle is acceptable. The only stipulation is that the vehicle must be powered solely by the rider"

http://www.nytimes.com/2009/12/15/science/earth/15bike.html

All the power is generated by pedaling; the electric motor in the hub is a machine, but so isn't a crank arm (a lever)? - so - let the sparks fly - 

--
Peter

"Question people's judgement, not their motives"
58 National Parks - 53 to go
Sent from a mobile  device - my Airstream

[Donald Perley]

Haha... for one thing, it would require the starting point to be the
low point of the route, right?

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[Peter Noris]

Hi Don,

Nope - we now allow starts at higher than sea level, and people drive to the start, getting a "free" gravity bump if the ride ends at a lower elevation- and the fact that most rides have a common start/finish isn't mandated in the rules, so that gas powered assist would be legal -

[Donald Perley]

OK.. never been on one with a net downhill.

On a technical note, this may link in with some battery work also
being done at MIT. Extreme charge rate Li batteries.

http://www.boston.com/business/technology/articles/2009/03/12/mit_scientists_charged_up/

[Peter Noris]

I was remiss in not finding the following link,  http://senseable.mit.edu/copenhagenwheel/  which goes into greater detail, including using your smart phone for gps tracking of your route (planned  and actual), caloric expenditure and various other metrics.

Combination with electronic shifting can't be that far off now that batteries are much less likely to become discharged.

Bike 2.0 ?

[Charles Lathe]

It looks to me like that wheel would be legal. However, for most of
us, it would be a disadvantage and not an advantage. There is very
little braking on most brevets. On mountainous routes where you might
actually brake once in a while, you spend much more time climbing and
the added weight of that wheel on a climb will be a strength sapper.
As soon as you start using any power the wheel makes -- if it actually
gets a chance to make any power -- for operating electronic equipment,
you're going to go backwards with energy expenditure.

The bicycle is an amazingly efficient machine. We hear arguments for
fat, soft tires and for narrow, hard tires; for stiff frames and for
flexible frames. The bicycle manufacturers move the head tube
bearings closer together to "stiffen" the front triangle and they move
the bottom bracket bearing further apart to accomplish the same
without ever telling us why closer makes stiff on one part of the
frame and space makes stiff on another.

At the end of the day, we're cowed by those cloddy looking people who
somehow continue to finish ahead of us all the time. The ones who
listened to the old adage: Don't buy upgrades. Ride up grades.

I suspect the MIT guys aren't big bicycle riders because they seem to
have figured that since cars and bicycles are all vehicles, they'll
respond to the same technologies.

Regards, Chuck Lathe
Franklinville, NC

[Donald Perley]

On Tue, Dec 15, 2009 at 9:14 AM, Charles Lathe <cohobi...@yahoo.com> wrote:
>  There is very
> little braking on most brevets.  On mountainous routes where you might
> actually brake once in a while, you spend much more time climbing

The distances for descents and climbs tend to be the same. The times
aren't the same because you're going down hill at perhaps 50 mph and
up the similar grade at 5 mph. If you aren't braking on the downhill
it is because all that energy is going into wind resistance.

If you used a generator brake to slow your descent to 20 mph and use
the captured energy to maintain 20 mph on the uphill for a similar
personal effort, you would more than double your average speed over
that stretch.

That's assuming that your battery will hold a hill's worth of energy,
but no la-la 100% efficiency.

[Greg]

This is simple. It's not legal. There's no way to ensure that the
rider is starting the brevet with no stored energy in the hub/wheel/
battery. So, some portion of the ride may be powered by stored energy.
True, the rider would need to pedal to replace the energy that was
consumed from the hub/wheel/battery, but any part of the brevet
completed on stored power would make it illegal.

Greg

[Donald Perley]

On Tue, Dec 15, 2009 at 10:31 AM, Greg <greg.o...@gmail.com> wrote:
> There's no way to ensure that the
> rider is starting the brevet with no stored energy in the hub/wheel/
> battery.

What leads you to say that?

[Kole Kantner]

I don't have any hard numbers on this, but I suspect regenerative
braking for this bicycle is very far away from 100%. The "highly
efficient" SON hubs are only around 60% efficient without any external
circuits or equivalent losses on the boost phase. I'm not saying the
SON really is extraordinarily efficient, but it doesn't take much loss
to quickly eat up any advantages from a bit of downhill charging. The
majority of the savings in a hybrid car are not in regenerative braking,
but instead result from the electric boost that allows the gasoline
engine to operate in the most efficient range most of the time.
Regenerative braking sounds great, though, and is worth including in a
car just for the marketing value even if the efficiency boost were
insignificant.

--Kole--

[Kole Kantner]

I think more of the savings in city driving result from cutting the
engine at stops and allowing the battery to assist with the frequent
accelerations from stops keeping the gas engine operating in the most
efficient range. I seem to recall regenerative braking adding only a
few percent if even that. If anyone has links to numbers on how helpful
regenerative braking is I would like to look at them.

--Kole--

Jan Heine wrote:

> At 10:18 AM -0500 12/15/09, Donald Perley wrote:
>
>
>> If you used a generator brake to slow your descent to 20 mph and use
>> the captured energy to maintain 20 mph on the uphill for a similar
>> personal effort, you would more than double your average speed over
>> that stretch.
>>
>

> Assuming zero weight for the batteries... You run into a problem that
> also is bugging hybrid cars: The batteries are heavy enough that on
> an overland course, where little braking is required, the hybrids
> often are less efficient than a well-driven, similar-sized pure
> gasoline car with similar power output.* In the city, hybrids score
> because the energy from gradual braking is converted into electricity
> rather than heat. They don't require careful driving to avoid
> braking, which makes such a difference in a conventional car.
>
> Modern electric trains, on the other hand, just feed the power back
> into the overhead catenary grid, so that trains slowing on downhills
> power other trains going uphill... Now that is an elegant solution,
> but hardly practical for bicycles.
>
> For the time being, the aero tuck at least helps to redress the
> situation partially, by increasing the speed a bit. Granted, hill
> interval training still are the best way to improve your overall
> brevet speed on a hilly course.
>
> In any case, a system to slow the bike on descents would take half
> the fun out of cycling.
>
> * Note that in North America, few gasoline-powered cars are available
> that are similar in size and power output to hybrids, so hybrids may
> still have an advantage on overland routes.
>
> Jan Heine
> Editor
> Bicycle Quarterly
> 2116 Western Ave.
> Seattle WA 98121
> http://www.vintagebicyclepress.com
>
>

[littlecirclesvt.com :: mike beganyi]

Why not ditch the regenerative braking and push SON to build a rear
dyno hub as well.
Front for lights and electro gizmos. Rear for charging your e-assist.
Add in a BB dyno or bottle generator to power the flat screen TV...

Then have the rack mounted e-assist or a Stokemonkey type device to
help out on the hills.
And we can have RBAs do a pre ride gear check to be sure everyone's
batteries are depleted - so if you ride to the start, turn the charger
off!




And to think that Peter took offense to my posting of the Sport Indent
concept that might add technology into the mix for processing brevet
cards / route passage.




On Dec 15, 10:42 am, Donald Perley <donper...@gmail.com> wrote:

[Greg]

As I understand it, the hub/wheel/battery captures energy that would
otherwise be lost and stores it for later use. As you ride downhill,
pedal, and/or brake, some amount of energy gets diverted to the
battery stored to be used at a later time. Let's say that the battery
can store some maximum quantity of power. I'm presuming that the
stored power is electrical. How can anyone at the start verify that
the battery has no stored power. It could be that a rider connected
the battery to an outlet to top it off before the brevet. Or, and this
would be tedious, I'll admit, the rider could put the bike on a
trainer for an hour before the ride starts and have someone else spin
on it to put energy into the battery, assuming that it's not possible
to connect the battery to an electrical outlet.

Only if the hub/wheel/battery started with no stored power would this
appear to be legal. And I'm not sure how an RBA could be expected to
visually determine whether a battery is fully drained or not.

Greg

On Dec 15, 7:42 am, Donald Perley <donper...@gmail.com> wrote:

[Eric Keller]

I agree. There is no battery technology available that survives
complete discharge; they all have much longer lifetimes if they are
used in a fairly small discharge range. For most technologies, there
is a fairly small voltage range between 90+% full and the minimum safe
voltage. I don't see how you could expect an RBA to become an expert
in battery tech.
Eric

[Keith Kohan]

If it gets more people on bikes it's great! --- On Tue, 12/15/09, Peter Noris <pno...@gmail.com> wrote:

[Wesley Cheney]

I could see loaded tourers getting a lot out of this, especially in hilly terrain.

Wes

Fotobywes.blogspot.com
Wescheneyweddings.com

*Stupid Hurts*
*Safety First*

---

[Greg Merritt]

On Tue, Dec 15, 2009 at 8:16 AM, Keith Kohan <bike2wo...@yahoo.com> wrote:
>
> If it gets more people on bikes it's great!

I had the opportunity to ride some conventional (non-regenerative)
electric city bikes.

Under hard pedaling at cruising, I didn't really perceive the motor doing much.

However, the stunning difference was getting going from a full stop.
It was relatively effortless.

I think that this assist-from-stop feature is the huge hidden
advantage of electric bikes that can really make them accessible to
more people.

If a regenerative system can extend their range, or allow them to
operate similarly with smaller batteries, it sounds pretty good to me.

-Greg

[Rob Hawks]

There is a rider who lives nearby that I sometimes come across who
uses one of these. He can't catch or keep up with me once we are both
well under way, but from a stop there is no contest, and I usually do
pretty good getting up to speed from a stop.

rob hawks
richmond, ca

[littlecirclesvt.com :: mike beganyi]

Just add some of those fast rolling GB tires and you'll be a Cyclos
Montagnard in no time! Even with the 'battery' penalty.

;)



On Dec 15, 11:08 am, Jan Heine <hein...@earthlink.net> wrote:

> At 7:58 AM -0800 12/15/09, Greg wrote:
>
> >As I understand it, the hub/wheel/battery captures energy that would
> >otherwise be lost and stores it for later use. As you ride downhill,
> >pedal, and/or brake, some amount of energy gets diverted to the
> >battery stored to be used at a later time.
>

> I like the concept. It's especially handy for those sprints, or to
> drop somebody on the next hill. ;-)
>
> Finally, finally, I'll be able to drop my buddies, simply by buying a
> new gizmo. ;-)

[Donald Perley]

On Tue, Dec 15, 2009 at 10:44 AM, Jan Heine <hei...@earthlink.net> wrote:

> Assuming zero weight for the batteries... You run into a problem that also
> is bugging hybrid cars: The batteries are heavy enough that on an overland
> course, where little braking is required, the hybrids often are less
> efficient than a well-driven, similar-sized pure gasoline car with similar
> power output.* In the city, hybrids score because the energy from gradual
> braking is converted into electricity rather than heat. They don't require
> careful driving to avoid braking, which makes such a difference in a
> conventional car.

AFAIK all the hybrids out now are using NiMH batteries, which are
significantly heavier for the same energy. A typical lithium battery
of 1 Kg might have a 200 watt hour capacity, enough to lift a 200
pound rider/bike ~1200 feet. (minus inefficiencies, but you will be
pedaling as well)

The big limit on regen braking with hybrid cars today is how fast you
can charge the batteries.
In the news clip I linked on MIT's new Li batteries, they are talking
60 to >100C charge rates, compared to maybe 4C for NiMH.

> For the time being, the aero tuck at least helps to redress the situation
> partially, by increasing the speed a bit. Granted, hill interval training
> still are the best way to improve your overall brevet speed on a hilly
> course.

If the climbing time is already many times more than the descent time,
you gain very little overall by adding a few MPH on descent.

With a car on a highway trip you don't have nearly the spread between
uphill and downhill speeds which you could close with regen braking to
improve the average speed.

[WMdeR]

Dear Peter,

I've idly wondered about regenerative braking etc for a while.
Actually, since reading a William Gibson novel in the early 1990's
where a bicycle anti-theft device consisted of a big capacitor charged
by regenerative braking....

Thank you for the article link.

"Is this wheel legal?"

Well,

ACP Article 2 from

http://www.audax-club-parisien.com/FR/index.php?showpage=312

<<Toutes les machines sont admises, pourvu qu'elles soient mues par la
seule force musculaire.>>

Transliterated into English:

"All machines are allowed, provided that they are moved solely by
muscular power."

Anything with a motor isn't eligible for ACP-sanctioned events, based
on this translation of the rule.

RUSA's translation is a bit more fluid, but perhaps doesn't capture
the full intent of the Rule. So perhaps RUSA-sanctioned events would
allow some form of energy storage to provide motive power, but the ACP
doesn't appear to do so. John Lee Ellis or Bill Bryant may have some
insight into the intent of the RUSA translation of the original
rules.

I do know the intent of the Cyclos Montagnards concerning this issue.
Their rules specifically penalize the use of battery-powered devices
(including lights) as accepting outside assistance. I can only
imagine the performance penalty they'd apply to a machine with power
storage for propulsion....

Best Regards,

Will

William M. deRosset
RUSA 2401

[Donald Perley]

On Tue, Dec 15, 2009 at 12:35 PM, WMdeR <wmder...@gmail.com> wrote:

> RUSA's translation is a bit more fluid, but perhaps doesn't capture
> the full intent of the Rule.  So perhaps RUSA-sanctioned events would
> allow some form of energy storage to provide motive power, but the ACP
> doesn't appear to do so.  John Lee Ellis or Bill Bryant may have some
> insight into the intent of the RUSA translation of the original
> rules.

A strict interpretation of the ACP rule would not allow the boost you
get on on a normal bike from riding downhill or with a tailwind (even
if disadvantaged by those same effects when going upwind/uphill).

[David Lafferty]

A cyclist (or other land vehicle) that travels at a constant speed
will theoretically finish faster than an identical cyclist that has a
constant power output. There are a few assumptions here:
1) Weight, rolling resistance, air resistance are identical for the
two cyclists
2) The total energy output by the two cyclists is identical
3) The course is hilly (on a flat course, their speeds would be equal)
4) The "constant speed" cyclist has the same efficiency at all power
outputs

This argument would suggest that an electronic or mechanical speed
governor would be an advantage over an unassisted bicycle.
Theoretically, any device which helps to regulate speed would help,
including a regenerative brake/motor, a flywheel, or even a heavy
bicycle.

This theoretical argument suffers in reality for two reasons:
1) Storage and output efficiency
2) Storage capacity

The "constant speed" cyclist would likely suffer in reality because
his efficiency would drop severely at the high power outputs necessary
to get over hills. On a steep enough hill, he probably would not be
able to maintain constant speed and would blow up trying to do so.

A bicycle with heavy wheels would be highly efficient at storing extra
energy and returning it to the road. However, the capacity is
extremely limited. Heavy wheels would help you ride faster over
slightly rolling terrain, but would be a liability on a real hill.

A flywheel or regenerative brake/motor must therefore have sufficient
storage capacity to maintain speed over the longest hills of a route,
and output enough power to maintain reasonable speeds over the
steepest hills. If it can accomplish those, it will improve your
average speed. Otherwise, it's just an extra gadget to haul around.

Food for thought,
David "I have two speeds: sitting and standing" Lafferty


On Dec 15, 12:43 pm, Donald Perley <donper...@gmail.com> wrote:

[Wesley Cheney]

Kole Kantner wrote:

I don't have any hard numbers on this, but I suspect regenerative
braking for this bicycle is very far away from 100%.

I'm not sure of the efficiency numbers, but long before the Prius & Insight came out, North American railroads have been running diesel-electric locomotives that utilize regenerative, or "dynamic" braking.  If it wasn't cost effective, it woudn't be widespread in a (relatively) conservative industry.

Wes

[WMdeR]

Dear Donald,

"A strict interpretation of the ACP rule would not allow the boost you
get on on a normal bike from riding downhill or with a tailwind (even
if disadvantaged by those same effects when going upwind/uphill). "

True. We could rewrite the rule to strictly specify from which
potential fields one may gain energy (or we could specify that a
course comes back to the same spot from which it started. Then the
net potential change = zero). Winds are tougher, because they aren't
strictly speaking, conservative, but I figure it all averages out
eventually....

However, as far as I know, all ACP events to date have been held on
Earth, in
Gaia's gravitational field, subject to Terran weather conditions.

In all seriousness, I think we can make a pretty good argument that
the intent of the rule is not to outlaw tailwinds or rolling friction
(good luck with that), but to render motors, rockets, and the like
against the rules, and to allow kick scooters, tricycles, hand cycles,
tandems/triplets/quads, velocars, roller-skis, and so on to
participate.

Cheers,

Will

William M. deRosset
RUSA 2401

P.S. The Martian brevets are justly well-known for their fast times
due to
low wind resistance, despite the severe terrain, but the low oxygen
content makes 'em tough for folks coming up from sea level on Earth.

What is the ACP policy on supplemental Atmosphere?

[Kole Kantner]

Do diesel electrics have a way of storing electric power?  If not, I wonder where the generated electricity goes?

--Kole--

Wesley Cheney wrote:

[Greg Merritt]

The grid, no? Just like home PV systems, I presume.

-Greg

[Kyl Scott]

Actually, they just take the electricity from the dynamic braking and dump it to a very large resistor bank, turning it into heat and blowing it out into the air.  While trains have friction brakes as well, the dynamic braking results in less wear and tear and saves on brake pad and wheel replacement, etc. and is used until more braking power is required.

They don't have giant batteries to store the energy from braking (at the power levels they use, it would take several train cars to house the batteries).  So diesel-electric hybrids just use the diesel engine in its efficiency sweet spot to drive a generator to create electricity.  This electricity is sent to motors down by the wheels.  This avoids the huge mechanical transmission system that would otherwise be required and is the main reason for the hybrid approach (efficient engine operation and no mechanical transmission - these electric motors also have great torque vs. rpm curves, too).  These motors are then used for the dynamic braking.

So regenerative efficiency on a train is 0% (all recovered energy is discarded).

Enjoy,

-Kyl

Wesley Cheney wrote:

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-- 
+-----------------------------------------------------------------------------+
| Kyl Scott,     Mixed-Signal ASIC Design,      Texas Instruments, Dallas, TX |
| email: hors...@ieee.org, kyl....@ti.com                   (214)480-3810 |
+-----------------------------------------------------------------------------+

[Ken Freeman]

I see what you're saying but it doesn't totally make sense.  Passenger trains I've been on seem to start silently, not with a great roar of diesels. 

Ken Freeman
Ann Arbor, MI USA

[Wesley Cheney]

Just like a hybrid car, they've got a battery pack. There's no mechanical linkage between the diesel engine & the wheels.  Rather the diesel engine powers a generator, which in turn sends power to "traction motors." in dynamic mode the power flow is reversed.  Diesel-electrics can run in silent, battery mode- especially useful in posh suburbs.

Fotobywes.blogspot.com
Wescheneyweddings.com

*Stupid Hurts*
*Safety First*

---

[Wesley Cheney]

Negative, not the grid.

While strictly electric locomotives (Amtrak, TGV) could theoretically return power to the overhead catenary lines & the grid, I'm not aware that it's actually done.

Fotobywes.blogspot.com
Wescheneyweddings.com

*Stupid Hurts*
*Safety First*

---

[Wesley Cheney]

Norfolk Southen just debuted a hybrid, battery-pack locomotive, where the batteries are recharged by braking.


 Thanks for the correction, Kyl!

Fotobywes.blogspot.com
Wescheneyweddings.com

*Stupid Hurts*
*Safety First*

---

[Greg Merritt]

On Tue, Dec 15, 2009 at 1:03 PM, Wesley Cheney <frie...@mac.com> wrote:
> Negative, not the grid.
>
> While strictly electric locomotives (Amtrak, TGV) could theoretically return
> power to the overhead catenary lines & the grid, I'm not aware that it's
> actually done.

Whoops! Too many subthreads and too many kinds of trains. I believe
Jan indicated that some electric (not diesel-electric) trains feed
back to the grid.

Bringing it back around... I took an electric train to & from my 200k
permanent on Saturday!!!

-Greg

[Donald Perley]

On Tue, Dec 15, 2009 at 3:47 PM, Kyl Scott <kyl....@ti.com> wrote:

> Actually, they just take the electricity from the dynamic braking and dump
> it to a very large resistor bank,

http://en.wikipedia.org/wiki/Hybrid_train has references for MFR's and
rail systems using regenerative braking to battery in their hybrid
trains. Also some hybrids that can run off diesel, 3rd rail, or
battery.

[WMdeR]

Dear Jan,

Thank you for the clarification. So as long as all power to complete
the ride is generated by the rider, directly or otherwise,, all's fair
for the C-M group?

As a practical matter, at today's energy densities (and charging
rates, apparently) for batteries, this has no practical import, but
consider the difference between pedaling 200W more or less constantly
with, say, an extra kilogram of regenerative capacity, or,
alternatively, 400W uphill, and 0W downhill without that extra kilo,
and ask yourself which is going to require greater fitness, a superior
motor, if you will, to obtain the same final results.

Managing one's speed to maximize the storage capacity and to use that
capacity fully becomes a point of optimization once one can store
significant amounts of energy for propulsion. One bleeds potential
energy into the regenerative braking system for later use rather than
"waste" the energy on high-speed descents and the resulting V-cubed
energy losses due to air friction. Descending above 30kph (until
you've got all the "power assist" you'll need for the next section
generated, anyway) becomes as wasteful a gesture as stopping every
time one eats a snack.

Others have implied the point better than I can above in the
discussion on average speed.

However, e-assist motors are potentially quite helpful in getting
otherwise sedentary folks out and riding. My mother, for instance,
has COPD, and cannot ride a bicycle uphill given her remaining work
capacity. However, a plug-in e-assist would help her out in the hilly
region in which she lives.

Best Regards,

Will

William M. deRosset
RUSA 2401

On Dec 15, 2:09 pm, Jan Heine <hein...@earthlink.net> wrote:

> At 9:35 AM -0800 12/15/09, WMdeR wrote:
>
> >I do know the intent of the Cyclos Montagnards concerning this issue.
> >Their rules specifically penalize the use of battery-powered devices
> >(including lights) as accepting outside assistance.  I can only
> >imagine the performance penalty they'd apply to a machine with power
> >storage for propulsion....
>

> Actually, we only assess a penalty if you use outside energy in the
> form of batteries, gasoline engines, solar power, etc.
>
> As long as the storage device for the regenerative braking is empty
> at the start, we would not assess a penalty at all. Cyclos
> Montagnards challenges are about teamwork and so there is no
> advantage in storing energy for a sprint anyhow...
>
> So you could even use battery-powered lights, if they were charged by
> a generator hub during the day, without incurring the (small) penalty
> we assess. What matters is that the rider provides all the power
> required to complete the ride.
>
> We only assess a penalty if your storage device is full at the start,
> and when it powers vital functions of the bike, which are required to
> complete the ride. We don't make a difference between propulsion and
> lighting - both are vital functions of the bike, and without them,
> you can't go on. (Your cell phone or your watch are not vital to the
> progress of the bike, and thus are your own business.)
>
> In racing, energy storing devices are outlawed specifically, by the
> way. Otherwise, somebody would have come up with a spring that gets
> wound up over the early kilometers of a stage, to be released for a
> final burst during the sprint to the finish line... They don't have
> rules about lights because they don't use lights...
>
> Jan Heine for the Cyclos Montagnardshttp://www.cyclosmontagnards.org

[Kyl Scott]

Sorry, I should have indicated freight trains.  I haven't crawled around the guts of modern non-electric passenger trains :(.  And even my freight trains are a bit older (70s-90s technology; pre lithium-ion).

The Japanese trains I generally ride are all electric (even the high speed ones) so they are silent.  I haven't been close to a state to state US passenger train (Amtrak) to see what they have in their locomotives.  Our local DFW commuter trains (DART) are also all electric.

I did go do some looking around, and I do see battery assisted diesel electrics, where the battery is used for power when stationary and for initial acceleration, so those should allow capturing some of the braking energy (subject to the battery charge current limits).  It also looks like there is a lot of other efforts into various diesel-electric-battery approaches.  I don't think any of them aim to recapture much or all of the braking energy for anything other than smaller, light weight commuter/passenger trains (the braking energy involved with taking a 5,000 ton (10,000,000 pound) 100 car freight train down in speed is rather large).

Thanks,

-Kyl

[TomMarchand]

You can accomplish the same thing by buying a box of tacks and
dispensing them on a ride. And it will be a lot cheaper.

[Bill Gobie]

GE's hybrid diesel-electric locomotive:

http://ge.ecomagination.com/products/evolution-hybrid-locomotive.html

A hybrid switch engine (used for pushing cars around switch yards) could be as stunningly efficient as a hybrid auto in city driving.

Bill Gobie

[littlecirclesvt.com :: mike beganyi]

Here's a vid, looks like they morphed a fixter hipster with a ... ???
I'm not sure what.
But he's coasting around in that building.

http://news.bbc.co.uk/2/hi/science/nature/8415379.stm

[Randon Nerd]

The commuter train I use to shorten my daily commute to 30 mile RT in
the winter is powered by "brand new" GE diesel-electric locomotive -
it has a beautiful V-18 turbodiesel powering the generator...and when
it pulls out of the station it REALLY revs up. It is definitely not a
hybrid but the engine is supposed to have a lower emissions than the
old one it replaced. We're in a "non-attainment"and using low-sulfur
fuel, it really doesn't smoke or smell all that bad - the train
engine, that is, not the passenger compartment.

Willie

[BLBradbury]

Kole Kantner wrote:
> I I seem to recall regenerative braking adding only a
> few percent if even that. If anyone has links to numbers on how helpful
> regenerative braking is I would like to look at them.
>
I think you're right. Regenerative braking is not the biggest source of
fuel savings for a hybrid car like a Prius. A major source of savings
is because the internal combustion engine can be used close to it's most
efficient power output rather than at the power output required at any
given point in time. Any surplus or deficit in power can be obtained or
sent to the battery. The efficiency of an internal combustion engine
varies greatly with the power it is being used at. Internal combustion
engines are most efficient at fairly high power outputs. Fast driving
wastes gas primarily because of aerodynamics, not because of the
engine's efficiency. Also having the electric motor to help frees
engineers to design an engine for maximum efficiency rather than
flexibility over a range of power outputs. An Atkinson cycle engine as
used in the Prius for example would not be practical in a non-hybrid car
because it lacks low end torque.

Jacques Bilinski

[BLBradbury]

> Compare that to my car, which has good power output from 1500 to 6500
> rpm, or a range of 400+%. The reason for the broad power band is that
> the car has only 5 speeds, yet needs to operate in a speed range of 10
> to 120 mph.
>
If you have a SUV with a 350hp V8 and only need, say, 15hp no
transmission can change that. All the transmission can do is adjust the
engine's rpm, not it's power output. You need some kind on energy
storage device as in a hybrid vehicle to do that.

[Ken Freeman]

It's well known among automotive engineers that more fuel savings is available if you can operate the engine at peak torque (really peak BMEP) all the time.  Some hybrid systems allow the IC engine to be mechanically decoupled from the drivetrain. 

CVT transmissions also enable this type of operation in cars. 

For riders with a narrow powerband, who haven't trained for flexible power delivery as Jan may have, 30 gears might approximate this operation. 

Then, there's the NuVinci.

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