Tuesday, December 31, 2013

Mid Drive Conversion

The first two bikes have motors that are built into the hubs, this makes for a clean and robust design.

Geared hub motor in rear wheel, no change in derailleur setup needed.

However this is the problem:
On my road, you get your speed up on the 7 to 12% grades for the 18 to 19% sections.

When I ride over to Woodstock, it is easier to get off the bike on the steep sections and walk.  This isn't as bad as it sounds, because I can turn the motor on low and have it pull me and the bike along.  (This would not be possible with a Pedelec or BionX style throttle control.)  To put this into perspective, in my car this is a second gear hill under good conditions, and when there is washboard it is first gear at 5-10 mph, which is not much faster than the bike.

The solar electric cargo bike motor is currently set up for 500 watts of power, which isn't enough for riding up this hill. There are a few ways around this limit:
-I can reprogram the controller for more amps.  This is easy, but drains the batteries more quickly and the motor will run hotter.
-I could put on a different battery with a higher voltage than the current 36 volts, (this is called over volting), as the motor is rated for up to 100 volts intermittently.  This is more expensive.
-A second motor and extra batteries would do the job:
Fast 2WD Electric Bicycle- Top Speed 50 mph, video credit: RNickeyMouse

Since my goal isn't 50 mph, but going up the steeper hills around my area, it is also possible to use a regular power level motor and battery pack, and connect it as a mid drive to the pedals so that the derailleur gear reduction system is used, just like shifting to a lower gear in a car. I've been avoiding a mid drive because:
-it is more complex (more things to wear out or break)
-at the higher power levels it wears out chains and sprockets quickly
-2 pawl freewheels don't like the power, so a good quality freewheel is needed, and a freehub is better
-if you shift without letting up on the power you can break stuff
-they are generally noisy- the good ones sound like a turbine (which is neat), the bad ones destroy any chance of a pleasant bike ride
-the width must fit between the pedals, so it must use a small motor, or a second chain to a remotely mounted motor
-a few bikes use the one regular chain, with the motor drive tied in to the upper chain section.  This gives you only the gears on the rear wheel, and it can not use the front gears
-many mid drives extend the gear reduction train upwards, which raises the center of gravity higher than a hub motor.  However I don't think this matters anywhere near as much as where the battery is mounted, and both types of bikes commonly use the front triangle or rear rack.  I've ridden a bike with a very large battery on the rear rack and it tended to oscillate.  One way some riders are getting around this is by carrying the battery in a backpack, such as in the video above, and also on some European mountain eBikes.

I'm trying to design for average riders and average budgets.  

Of course it is possible to get a little obsessive about a mid drive setup:
Astro 3210 RC motor homemade setup running at 7000 rpm, photo credit: electricbikes.com

Which usually results in something like this:
Electric Downhill Bike (66 mph run), video credit Kim Reeg

Unfortunately this kind of usage is a pretty heavy draw on the batteries, there is a large aerodynamic drag and the range suffers.  I don't think there will be many of these bikes, as it is just too complex and costly.  In addition to the drive setup, you also have to upgrade hubs, rims and front forks, and start using moped or small motorcycle tires and brakes.  For a cargo bike it needs to be a little more balanced, trading off some of the performance for better range.

Many countries in Europe or Asia have set a power limit of 250 watts for electric bikes, or about the power of a professional bike racer.  While the solar electric cargo bike's average energy draw is 196 watts, in real life this turns out to be too small for getting the bike and cargo up many hills, and the power draw goes up to the 500 watt limit while speed drops.  I can imagine riders that aren't in good health wanting more power.  Most European manufactured drive systems (AEG, Bosch, Conti, MPF, Panasonic, Yamaha) have 250 watt motors and must be built as a mid drive gear reduction system to make it work- you shift down and just go slower.  I think it would be easy to overload a 250w motor while hauling loads in Vermont and greatly shorten it's life.   However the 500 watt hub motor is close, and with gearing added might be a respectable ride up my hill.  Looking around for good mid drive examples, Audi's eBike is pretty well balanced and has received a lot of positive comments:
Audi e-bike, at Worthensee show, ridden by Julien Dupont.  The bike in this video probably is traveling around the legal European electric bike maximum of 25 kph (15.5 mph), and you will notice that Julien is riding with his helmet unsnapped.   It also has a few things that could easily be left off of a cargo bike, such as the carbon fiber frame and wheels, and wifi control.  Most bikes like this have a custom gearbox at the pedals with slip clutches for the pedals and motor, and internal gears.

The geared hub motor was a blast for 500 miles last season, and I will continue using them, but I admit to my usual need for speed up long, steep hills (or at least riding instead of walking), so I am thinking about mid drives.  I also want the assist to be strong enough for people with different levels of health to be able to ride.  There is plenty of power available from an electric bicycle, as you can see from just a few seconds of this video:
Extremely high power tadpole trike, video credit Matt Schumaker

Gearheads.   I'm just going out for groceries.

The design problem is how to trade some of the power for range, but still have it there for the hills.  There are several ways of connecting a motor as a mid drive, and I'm waiting for all the Christmas presents to arrive so I can start experimenting.

Thursday, December 19, 2013

Helmets and safety

When I'm talking with people at events about replacing my car with the solar electric cargo bike, the elephant in the room seems to be safety. I am often asked if I wear a helmet by a person with a concerned look on their face.  For the most part I answer a polite "Yes" to avoid being misinterpreted, because it is a subject too complex for a half minute visit.  However a large obstacle to more widespread use of bikes for everyday purposes is the sense of comfort a rider experiences, so this issue needs to be covered.

I'm well aware that helmets are a contentious issue, as I've been riding motorcycles for almost 50 years and have heard a lot comments about them since day one.  (Maybe the reason this post is so long is because of that experience.)  I'm also sure there are some very serious people with strong opinions reading this that think safety is not open for discussion, so I'd like to start off with this absurd video:
The difference between an accident at 30 mph and 50 mph.

Next, I'd like to repeat that I am not an rabid bicycle advocate. I've owned cars, motorcycles, bicycles, horses, and have driven all sorts of construction and farm equipment.  I learned very young from some motorcyclist friends that cars were dangerous "cages", but I was too in love with Porsches for that to sink in very far.  I've been part of automobile, motorcycle, and thoroughbred horse racing efforts, and I've gone very, very fast, but I also love walking.  My viewpoint is about as open and equal use of the roads as anyone can be.

The prevalent concern now about bike helmets does not fit with my past experience.  Why does there seem to be such a widespread emphasis? In some people it was borderline fear.  I had ridden my bike everywhere around town solo without a helmet for a dozen years when I was a kid, and taken some awful spills.  But overlapping with this time, I had also ridden a motorcycle off road for 6 years before getting my drivers license, wearing a 3/4 helmet (covers down past the ears but not the face).  Both the bike (on the road on steep hills) and motorcycle (off road) top speeds were similar (about 45 mph), but I got hurt more seriously on the motorcycle even though I wore a helmet.  Nowadays I use a full coverage helmet when on my motorcycle, but on the bicycle?  I needed a more complete viewpoint.

Reading through websites about the effectiveness of bicycle helmets to find an answer, it became apparent the authors were polarized, just like the earlier motorcycle helmet arguments I'd heard.  Several studies proving helmets reduced injury would be followed by several saying they did not.  A few even concluded that helmets made injuries more likely, or that a decline in head trauma was matched by a rise in neck trauma.  Both sides had reputable studies from hospitals, universities, health care institutions, or government transportation agencies.  I was truly 50/50 about wearing a bike helmet- if even the meta studies could not consistently agree on a conclusion, then there was no trend for me to support. After 23 injury studies I gave up.

My personal usage position was that a half coverage bike helmet is almost a joke compared to my full coverage motorcycle helmet.  There is minimal side, face, or back impact protection, and the ability to take a hit is a small fraction of the motorcycle helmet's thick molded shell and lining.  (I believe one actual bike helmet standard is protection from a fall frontwards while standing, which would be a drop of five feet with minimal momentum.)  The bike helmet's main protection will be for a mild impact to the top of your head.  It probably will help somewhat in other situations, I've learned from off road experience that even leather gloves and decent clothing will help keep your body together in a crash.  If you want to wear a helmet I would not discourage you.  But the constant promotion of bike helmets seemed out of proportion to their value, and started to make me feel cynical about them, like this:
Good safe bicyclists on rock wearing helmets! Bad unsafe pedestrian on left without one!
Source: Kejeragbolten, Norway

I did come across one piece of information I could support:
This identifies speed as one of the main factors in the severity of injuries, (in other words go slower if you want to be safer).  My plans for fast cargo bikes had hit a bump in the road....   Perhaps if I kept it under 30?

Since the studies of accident injury data had been so inconclusive I stepped back to traffic fatality statistics, because they are much more black and white, someone is dead or they are not.  Here are national statistics for the US:
Source: National Highway Traffic Safety Administration, Fatality Analysis Reporting System (FARS)

So in 2011 there were 677 bicyclists that died.  That was definitely not good, and should be improved.  There were also 4,432 pedestrians that died, however I don't remember hearing any safety messages that I should wear a helmet when walking down a sidewalk, and there is not 6 times as much concern over the dangerous activity of walking.  Of course there were even more motorcyclists that died - 4.612 - because they have a reputation for being very dangerous (sorry, cynical again).  But most interestingly,  22,448 occupants of vehicles died- when was the last time you wore a helmet in your car?

It is surprising that bicycle fatalities are so low compared to cars, because there are known to be idiots doing stunts on bicycles (I did), but in general cars are equipped with seatbelts, impact bumpers, collision crumple zones, safety glass, air bags, carefully designed dashboards, and they form a protective cage.  The safety campaigns about bicyclists wearing helmets seemed very misplaced.  What was going on?

To be sure that the figures weren't anomalies, I checked the Vermont fatality statistics:
Source: Analysis of Fatal Crash Data: Vermont 2006-2010

Bicyclists are the bottom line.  In 2006, 2007, 2008, and 2009 no bicyclists died, and in 2010 one died.  In comparison the total other fatalities for those years were 87, 66, 73, 74. and 70.  I do not wish to make it seem like a rider can't get hurt on a bicycle, but on the other hand it appears to be one of the inherently safer forms of traveling- it is slower and simpler.  The message of how dangerous biking is really does not seem to mesh well with reality.

Another way to look at this data, is that no vehicle exists that will keep you safe in a crash.  Not walking, not bicycling, not cars, not trucks. or for that matter from recent news, not planes or trains.  The impermeable safety of your car is an illusion.  Also, the faster you travel, the more severe the injuries will be.  The 50/50 chance of survival point for pedestrians appears to be a little bit above 30 mph.  The conclusion I reach is that the best path to safety is minimizing the chance of crashes, not protection afterwards.

I should also say that there are approximately twice as many bikes in the world as there are cars, (many governments do not have accurate statistics on bikes), so lower accident statistics for bikes are not because there are less vehicle miles traveled than cars.

I apologize for not finding citations for this, but I know that falls are a leading cause of injury and death, particularly for seniors.  Logically there should there be an OSHA safety campaign ensuring everyone wears a helmet around the house, especially elderly people going down stairs and people going to the bathroom.  

It was time for a reality check.  I started looking at pictures and videos to see how riders in other parts of the world used helmets.  I noticed that despite very few riders in Copenhagen or Amsterdam wearing helmets, there were no reports of horrible survival rates when riding a bike, even though that biking population is upwards of a million people, and rides over 2 million kilometers each day. Then I noticed that through out Central America, and down into South America, there were almost no helmets, their Ciclovia's were big parties.  Finally, there was India and China, with hundreds of millions of riders- definitely the largest samples- and again there were very few helmets.  (I've posted some of the more interesting videos in the sidebar under "Traveling in other places".)  If you look in other places, for example the wall page of Women on Wheels, (which is about women who are traveling solo around the globe, a link is in the sidebar), it has 48 riders who have a helmet on or are carrying one on their luggage rack, and 39 without a helmet.  In the end, I was forced to conclude that wearing a helmet is not a requirement for riding a bike.  A distinction must be made between competitive racing cyclists at 30 - 40 mph, and average commuters at 8 - 20 mph. The overwhelming majority of people in the world do not wear a helmet when bicycling.

I would ask that you take everything you feel or think you know about bicycling on Upper Valley roads, and compare it with this video. "Cycling to School, Culemborg, Netherlands" by NL Cycling:
There is so much, so different, than cycling here in the UV, (and it isn't just the separated cycling path), that I have to question whether the common conception of cycling here is correct.

Returning to the Copenhagen and Amsterdam statistics, there was a time when bicyclists were being injured above historical averages.  The post war affluence of the 1950's and 1960's allowed more people to own cars, bicycle mileage dropped but bicycle accidents increased (!), and the segment of the population that suffered the most was children.  In response there were many grassroots campaigns during the 1970's to prioritize transportation infrastructure for bicycles, and injury rates declined, (child deaths went from 400+ in 1971 to 14 in 2010), even though bicycle miles increased.  The inverse correlation of bicycle miles traveled to injuries points out that bicycle safety is not tied to bicycle use per se, but that there is a direct connection between bicycle accidents and automobile use.

This points out that a second main factor in bicycle safety is the interaction with automobiles.  And because of the speed differential, bike helmets are not going to be very effective.

Hmm, is the focus on helmets a United States car culture phenomenon?  Post WW2 we relegated bicycle use to mainly sporting usage in favor of cars.  I am aware that GM, Firestone, and Standard Oil conspired to buy up all the streetcar lines they could in the mid 1900's and rip them out, could helmet promotion be a similar negative marketing campaign to promote auto use?  I can imagine automakers pushing back when they see data like this:
Global Bicycle Sales (upper line) vs Car Sales (lower line), source: Worldwatch Global Insights

The above graph does not include a surge in bike sales from 2008 to 2012 due to electric bikes, (mostly in China, source: Navigant 2013 eBike market summary).  Also, in 2012 bicycles outsold cars in all European countries except Belgium and Luxemborg:

Bicycle vs car sales, selected European countries (others are similar), 2012,
thousand of units, see link above for sources and other countries.

In 2009 Amsterdam instituted a traffic safety campaign, urging bicyclists to wear helmets.  Bicycle ridership entering the core of the city (where there are automated traffic counters) immediately dropped 5%, or about 10,000 bicyclists per day.  Britain's motor safety council did the same thing, with similar results. Australia passed a mandatory helmet law in 1991, and after disastrous public health results has tabled it in 2013.  (Please see the two videos that I've posted in the sidebar by urban planner Mikael Colville-Andersen talking about the Amsterdam studies.  Australia can be read about at http://www.cycle-helmets.com/ )  Helmets discourage ridership.  Now we are starting to talk about a truly large safety issue- Public Health -which I'll mention more about below.

 Fear makes people do strange things. I define fear as the absence of life.  In the sidebar I've put a link to "Culture of Transportation Fear" in the "Lets Get Serious" group, that discusses helmets and the media portrayal of bicycling as dangerous.  These messages are effective, sometimes they go too far and I occasionally have to remind myself that I was able to bike when I was 10 years old, on the street, and it was Ok.  As Colville-Anderson remarks in one of the videos, where ever he finds fear, he also finds someone lined up to sell you something.

I love conspiracy theories as much as the next person, but I'm not sure the auto industry is smart enough to pull off a campaign against bike riding, (look at Detroit).  The impetus behind helmet programs seems to me much simpler and more deeply ingrained- we are programmed to think in terms of the automobile, this is our norm. Street engineers design for the auto, and Traffic planners plan for automobile traffic.  Most bicycle helmet programs are run by government organizations whose main concern is automobiles.  When something is wrong, it must be made better for the automobile, we insist that people other than car drivers wear the helmets:
Conversation with an Engineer,  Source: Strong Towns

US transportation planning is not alone.  In the last 4 years car ownership in China has exploded, and there has been a simultaneous surge in accidents.  Traffic planners in many large cities have blamed the bicycle riders, not the new factor which is cars, and closed or narrowed down bicycle lanes.  This is a catastrophe for China's congestion and air pollution problems, so Beijing has had to order the bike lanes reopened.

Unleashing the power of fossil fuels is an addictive thrill for the reptilian part of our brain, which has spent most of history at walking speed. This is like flying by jumping off a cliff.

It is hard to see our transportation from a different angle.  A basic change would be recognizing cars as the more capable machines, and place the burden of fitting in on them.  Theoretically a car is subordinate to a bicycle is subordinate to a pedestrian, but that is not what the design of our streets say.  At the present moment a driver can simply say "I didn't see him", and be released from responsibility, thus placing bicycles subordinate to cars.  What if that option was not available, and our streets were designed so that it was not possible?
Cars subordinate to bicyclists, Source Bicycle Alliance of Washington

The above photo is called "We can dream", but Copenhagen and Amsterdam have been building transportation infrastructure for the last 30 years that highlights bicycles, and car owners drive like there will be bicyclists there.  During interviews in several videos there I've heard people remark that they ride bikes because it is easy, their relationship is based on comfort, not on fear:

Bicyclists waiting at an intersection, (note that there are no helmets).
Source: How Copenhagen Became a Cycling City, Niels Jensen, Planner, City of Copenhagen

If you make it easy to ride a bike, people will ride bikes.  If you make it easy to drive a car, people will drive cars.  In the US we currently devote most of our road works budget to making it easy to drive cars.  This change is where safety really lies.

Stroller racks on a bus, New Zealand, 1950's
Do you find that this idea makes sense?  If not, why?

I am sure that some people reading this will object that cars are necessary to keep our economy running, to which I reply that how many people bicycle and walk on a road is a good indicator of how safe they feel on that road.  (see for example the links on this page: http://www.aviewfromthecyclepath.com/2008/08/pit-canaries.html )  This raises the bar from a material goods level, to a true quality of life issue.  It is not good enough for a road to be rideable by young males with reflective protective gear on good equipment in good weather, it has to be comfortable for 99% of riders in regular clothes on average equipment in most weather. This is how you encourage people to ride.  The true safety issue is not helmets, but quality of life and participation in health promoting activities.

Road markings in Australia

Moving your body is not a new idea:
"Excess eating of sweet and fatty foods, lack of exercise and excess of sleep causes obesity.  There is impaired tissue metabolism leading to weakness and degeneration of tissues.  There is a coating and obstruction of different channels in the body resulting in decreased supply of nutrients to tissues leading to death... exercise may be protective."  Sushruta Samhita, 600 BC
This quote is from a Australian public health report conclusion that commuting on a bicycle is about the most beneficial exercise program possible, as it is active enough to trigger the body's healing responses, but not so active that it causes acute problems, it is easy on joints, and very importantly it is done regularly:    http://safety.fhwa.dot.gov/ped_bike/docs/cyhealth.pdf 

If helmets cause a 5% drop in ridership, then they truly are a safety factor, but in the wrong direction.

The summary at http://www.cycle-helmets.com/  of the tabling of Australia's national mandatory helmet law in 2013 sums it up.  Particularly sad is the note that the number of children riding or walking to school went from 80% in 1977 to the current level of 5%, with the decline starting with the passage of the mandatory helmet law in 1991.  The mandatory law contributed to Australia being the fattest nation on earth in a 2008 diabetes study.

This TED talk "Bicycling for Life" by Mark Martin at LSU looks at many of these points:

My current view of helmets and bike safety has become:
-Bike riding is one of the safest forms of transit, with the lowest fatality rate (both nationally and in my state), and a less severe injury rate, due mostly to a slower speed than other vehicles.
-The inherent safety of bikes does not mean it is Ok to ride mindlessly, all users of a road have a responsibility to drive safely.
-Bicycle helmets may or may not help in a crash, and may be of limited effectiveness because they are designed for very low speed impacts..  Bike helmets are not one of the main factors in injury severity, and Magical Powers should not be ascribed to them.
-Bicycle helmets do deter people from riding.  Mandatory helmet laws have been shown to be a bad idea, and even voluntary public education helmet campaigns have caused loss of ridership.  Because of this safety campaigns should not focus on helmets.
-Bike riding should be encouraged by public health agencies, because the benefits far outweigh the risks.
-Most importantly, safety campaigns are more effective when:
1.  They are focused on separating fast moving vehicles from everyone else that uses the road (such as in Amsterdam and Copenhagen).  Infrastructure is fail safe, and protects all riders regardless of their skill level.
2.  They review rules of the road and proper bike usage (similar to Driver's Ed for car drivers)

A website that reviews many best riding practices for bicycling is Mindful Bicycling:   http://commuteorlando.com/wordpress/2009/06/03/mindful-bicycling/

Dr Morgan Giddings also has a shorter list of 7 main considerations in her essay for Chris Martenson's Peak Oil website, about 1/3 way down this page:  http://www.peakprosperity.com/quiet-revolution-bicycles-recapturing-role-utilitarian-people-movers-part-ii 

Most of bike riding is common sense and similar to a car, such as if you ride at night, drunk, without a headlight and tail light, you are asking to die.  A few other things that I've noticed with the cargo bike:

-My traveling speed is much too fast for a sidewalk, and I've also read that where sidewalks go across roads at intersections are a leading location for accidents, so I don't ride on sidewalks.
-On a motorcycle my preferred lane location is towards the right side of the left tire track, but this is not possible on a bike on the open road.  However in downtown White River, Hanover, or even Hartland's two stop signs, I can keep up with traffic, and I ride in that lane location just like on my motorcycle, obeying all lights or traffic signs, and signaling.  Drivers treat me like a motorcycle.  (I should mention for people unfamiliar with these towns that there are no bike lanes.)  Out of the center I ride over to the right.

A little bit of humor- Stephane Bertrand is riding safely over to the right
on this section of Russian steppe highway that is under construction, 
and has red flags on his solar panels to warn other motorists.
Also note his helmet is safely protecting the headlight.
Photo credit: The Sun Trip, see link in the sidebar

-Bicyclists have a legal right to use the road- do not ride so far over to the right when the road is narrow and conditions aren't safe that it encourages car drivers to try to squeeze by you, drivers must pass safely.  Vermont law is 3 feet minimum clearance with an additional foot for every 10 mph above 30 mph.  On the other hand, the law also states that bicyclists traveling at less than normal traffic speed shall ride as far over to the right as safely possible.  There are responsibilities both ways.
-Something new I've had to learn is Dooring:
The Door Zone, Source: Allston-Brighton Bikes
Ride a few feet away from parked cars- do not use the right side of the bike lane.

In properly designed streets like Amsterdam or Copenhagen, Dooring can't happen, cars are parked on a diagonal, or removed from the travel lane entirely. The separation also makes pedestrians safer. Infrastructure is the fail safe way the way to go, good infrastructure stops mistakes from turning into something worse.  In my opinion (warning!) infrastructure is going to become more and more important, as we realize that roads are not just for cars.

My understanding of bicycle helmets now is that they offer limited protection, and a much better approach to safety is learning half a dozen to a dozen pointers about bike riding to actively avoid crashes in the first place.  (Such as how to use left hand turn lanes, lane placement, watching for right or left turning cars, or dealing with right side merge lanes.)  Next most important, I would like to see engineers and planners move away from spending most of the transportation budget on cars, and make it easier and more comfortable for most people to use bikes or walk.
Riding the solar electric cargo bike has been a blast, and drivers in my area have been great.  In the last summer and fall only one driver passed so close that it bothered me, but that person was greatly outnumbered by several dozen drivers who actually waited for me at intersections or narrow parts of a road.  On the bike I've gotten to say hello to many people I would have ignored if I was in a car, and it's been very rewarding.  It just plain feels good.  By all means if you are concerned about helmets then wear one, but don't make them a priority over good riding skills, and don't let them stop you from enjoying the far greater benefits of riding.

Sunday, December 8, 2013

Cycle Analyst and Analogger

To be able to compare the bakfiets and the longtail, I've chosen a very good speedometer. The Cycle Analyst can be ordered with an external shunt and be used on any electric vehicle, but the model used on the Bakfiets was designed to interface directly with the motor controller, and has a 6 pin plug in.  This uses the shunt inside the motor controller and should be pretty accurate, as the shunt value is specified by the factory to two decimal places.  Unfortunately this CA is not able to use feedback from the motor hall sensor phase signals to determine speed, because the geared motor has a slip clutch built into the gear carrier that disconnects the motor from the tire.  The CA installed on the bike needed to be equipped with an external sensor on the front wheel for measuring speed.

There is a wealth of performance information that is tracked, the easiest way to explain is to run through the screens:

Current Battery Voltage, Speed in mph, Current Watts energy use, and Miles traveled on trip

Same as first screen, but with Miles toggled to Amp hours

Total Watt hours used on trip, and Watt/hours per mile (this is similar to miles per gallon)

For motors that are direct drive- Regeneration electricity.  The geared motor can not do regeneration, but a very tiny amount amount usually shows up, because when the motor is turned off the collapsing magnetic field inside it generates a back emf that feeds electricity backwards.

Same Regen screen as above, toggled to show Forward (normal direction) Amps

The minimum and maximum Amps, and minimum battery Voltage.  Minimum Amps will go negative with regeneration.  Maximum Amps is programmed to be 15, but I have decide not to change the shunt value to lower the Amax to 15, because it would reduce the Wh/mile below the 13.2 average, which is not likely to be correct.  Volts minimum is how low the battery drops under a heavy load, and an older battery will drop more.

Maximum Speed, Average Trip Speed, and Elapsed Time for trip (total of any time the wheels are turning)

Number of Cycles and Total Amp hours drawn from battery, and Total Miles traveled since the memory was reset.  LiFePO4 batteries have a 1500 to 3000 cycle lifetime depending on how hard they are used, and usually the battery dies from age instead of cycles.

This is pretty much all the information needed for the average cyclist, and even one using the speedometer for light training purposes.  However since two separate bikes are being compared, it would be useful to compare the differences going up or down a hill, or cruising along flats.  A data logger (Analogger) was added to the speedometer for a closer analysis.
To ensure correlation, GPS data is written alongside the Amp hours used, Volts, Amps, Speed and Distance.  The data file looks like this (new values are written on a defined interval, currently about every second):

Ah V A S D
3.7861 40.35 0.00 0.00 11.183
3.7861 40.35 0.00 0.00 11.183
3.7861 40.35 0.00 0.00 11.183
3.7861 40.34 0.00 0.00 11.183

The corresponding GPS-NMEA information is written out in 19 sentences for sequential locations.  This gives data that should be a very close fit when comparing performance between the bakfiets with geared motor, and the longtail with direct drive motor with regeneration.

Saturday, November 30, 2013

The Pope gets an Electric Bike

There are a lot of people who have eBikes now, most of them are the usual suspects when it comes to caring for the environment- Ed Begley jr, Darryl Hannah, William Shatner, Prince Charles, Leo DiCaprio, Arnold Schwartzenegger, Adam Savage, Miley Cyrus....

As a matter of fact, when Arnold got into eBikes, he also set up a $1500 rebate for the purchase of new electric motorcycles.  But that is California.


Back in July the Pope got an electric bicycle.  In this picture Dr Dieter Zetsche, Chair of the Board of Mercedes Benz, is handing over the keys to a Daimler Smart eBike.

(photo credit the Vatican)

Friday, November 29, 2013

Sustainable Hanover Transportation Expo

The Transportation Expo in Hanover on November 16 was a lot of fun.  Sustainable Hanover arranged to use the Richard Black Community Center for Saturday morning, and had several electric and hybrid cars out in the parking lot, as well as organizations like Advance Transit, Hanover Bicycle and Pedestrian committee, Upper Valley Trails Alliance, and several bikeshops, in the building.  I thought it was great because I finally got to meet Larry Gilbert of Zoombikes and try out an Evelo ebike.  There was good crowd, and another half dozen people took test rides on the solar electric cargo bike.
The temperature was a little cool at the start, but quickly warmed up under a clear blue sky, a great day for test bike rides.  Larry had both regular style electric bikes, and a trailer with an electric motor for pushing a bike along.  Hoyt Alverson brought his homemade ebike that had extra towing power, and the solar electric cargo bike held down the utility commuting side of things.
The parking lot had Toyota, Nissan, Ford, Chevy, and two Tesla electric vehicles for people to look at.

Riders were eagerly waiting for test rides on the solar electric cargo bike.

The usual result of a test ride- a big grin.

A test rider pausing to talk with friends before a test ride around the block.

Regenerative braking

I rode down to the Thanksgiving day community supper yesterday (5.5 miles each way), because I wanted to ride a bit while thinking about the design of the second bike.  I rode a regular bike so the solar electric cargo bike wouldn't get dirty (the roads have been sanded and salted).  It was a little cool- the daily average temperature was 23 F.  In addition the daily average wind speed was 11 mph, gusting to 41.  However I was very comfortable, with a polar fleece hat under my helmet, neck warmer, and work coveralls on.  (I suppose if I was more fashion conscious I might have worn ski clothes.)  The only discomfort was on the way home, as I ate too much, and did not feel like pedaling up the hills, an electric motor would have been really nice.  I noticed two things on the ride- that traction was pretty much normal, and that the regular bike (even with knobby tires) was slightly easier to pedal than the solar bike (with the motor turned off).  I'm not sure why it was easier, some reasons might be:
-the slip clutch in the electric motor is dragging slightly (with a medium push, the motorized rear wheel spins about 2 turns, and the regular bike with a freewheel spins about 10 turns)
-the cargo bike's weight might make more of a difference than I thought
-the frozen dirt roads were noticeably easier to pedal on than the softer, thawed, sunlit sections that would be more similar to previous cargo bike riding

It does point out the quantity of energy that a bicycle uses is on the small end of the scale, and small changes can make a difference.

The mpg should be more like 2500, must be going up a hill.
(My apologies to Prius owners for this display simulation.)

Regenerative braking (regen) on a bicycle looks like it will be a grey area that might get lost in smallness, and the only way to find out for sure will be measuring energy use next summer on the second bike with the direct drive motor.  (The first solar electric bike has a gear drive motor with a slip clutch, and cannot do regen.  Mid drive bikes also have slip clutches.  See my blog post about The motor for more info.)  Some considerations for now are:

To put things in overall perspective, the simple kinetic energy equation:  Energy = half of mass times velocity squared, (E=0.5mv2), can be used to compare a bike and a car.
Using data from last summer:
-the bike's average speed was about 15 mph, and an average bike and rider might weigh 200 pounds.  Stopping to 0 mph would yield 1.13 Watt hours (before system losses)
-My car's average speed was about 26 mph, and I'm estimating the weight at 3000 pounds.  Stopping to 0 would yield 51.1 Wh (before system losses)
(I used average speeds instead of traveling speeds to be more representative of all situations.)
Stopping the car yields 45 times as much energy.  The question becomes, "Does the small amount of energy from bicycle regen matter, compared to other energy flows of the bike?

To start, I'm going to refer to "Is Regenerative Braking Useful on an Electric Bicycle?" by Brent Bolton of EcoSpeed LLC:
He covers many issues that make bike regen questionable, such as:
-The large number of stops needed to get 10% more range
-System losses (averages might be: generation about -5%, charging the battery -10%, discharging -10%, giving a -25% total loss)
-A battery has a maximum rate for accepting energy, and must discard more than that (for example going down a very steep hill)
-Parasitic drag of a direct drive motor (which I'll explain more below)

I can add four more factors to Brent's list:
-From my house to the center is an 800 ft drop in elevation.  If I charge the battery before leaving home, it can't accept any of the drop as regen energy on the way down, but will still use the usual amount coming back
-Much of a bike's energy load is air resistance, which is not recoverable
-Terrain will affect regen, because long, medium descents will yield the greatest regen, full stops that are more common to flat areas are not as effective, and steep descents that dump energy will actually cause a loss.
-Since the cost of a bike's electricity is so small, perhaps the cost of regen capability is better spent on a larger battery

Parasitic motor drag is a special situation.  Regen on bikes is done by electrically switching the permanent magnet motor to run as a generator.  The motor has to be directly connected to the wheel, if there is a one way slip clutch to allow coasting, the wheel can not drive the motor for regen.  The problem is that the magnets are attracted to the steel motor poles, and without power applied they resist moving from one pole to the next.  If you have ever turned a stepper motor (such as on a computer printer paper carriage), you've felt the cogging as the magnets moved from pole to pole.  This drag on a direct drive ebike, when the power is turned off, feels like riding with a soft tire.  In a car this doesn't matter, as the baseline drag loads are large enough that a motor has to be powering the car all the time (except during braking).   However bikes spend a lot of time coasting with no motor on, they have a state in between the motor being on, and motor regen, that helps make them very efficient.  An ebike direct drive motor can be turned on slightly to give the illusion of coasting, but does the regen energy make up for this loss?

In Vermont most roads run along valley floors, with a long steep climb and then a long descent to get from one valley road to the next.  I would love to have regen instead of having to hold the brakes during the descents, would this make regen viable?  Would local urban use in WRJ be different?  Since there are so many variables, the easy answer will be simply comparing the Watt hours per mile of the second bike that has the direct drive motor with regen next summer, versus the Wh/m of the Bakfiets without regen from last summer.  An even closer comparison will also be possible using data from the Cycle Analyst data logger on trip sections.

Monday, November 25, 2013

Inside the cargo box

The cargo box was designed to fit 3 five gallon buckets, for carrying compost around to community gardens. At first the lid simply fitted over the box using rabbets cut into the lid frame to hold it on, so that I could completely remove it for large loads, or for a person or dog sitting in the box.  But it was awkward opening the box and setting the lid down while holding groceries, so I added some hinges:

This meant my dog could no longer ride unless I unscrewed the hinges, but it has turned out that I wanted the lid for most trips anyhow, for both PV power and load protection (from the wind at 35 mph, and occasional rain).

The only time the load has gotten wet was once when I didn't screw my water bottle lid on tight and put it inside the box.  Then I found out how watertight the box is.

The box is mostly cargo space.  The original design had the battery outside, but it ended up inside with all the electrical devices for weather protection, and an inside cover to restrain the battery and protect everything from getting trashed by the load on rough roads:

On the lid at left is the controller for the solar panels, and the left back wall has an ignition key and a dc to dc converter for the lights (both hard to see in this photo), the blue battery is in the center, and the motor controller is on the right.  It's good to have the controller mounted in a protected open area, as it does get warm and needs air circulation around it, however I've also seen two controllers that were mounted outside which short circuited when rain got inside them.

The slots in the back wall are for seatbelt loops for use with a child seat.

If I were to build this bike again, one of the changes would be shortening the box by 7 to 8 inches, so that it would fit just the battery and two buckets.  It has been more than large enough for carrying groceries and recycling.  Another change would be to use a monocrystalline cell frameless and glassless solar panel as the lid.  The two modifications together should lighten the bike by 20 pounds, (although also be a lot more expensive).

FlyKly market position

I've just been asked about the FlyKly again, (I think their search engine optimization people are working overtime), and thought a post about it might be appropriate.

(photo credit FlyKly)

The FlyKly is a rear wheel replacement that has the batteries and motor built inside the hub, making it very easy to install- you simply replace your bike's old rear wheel with it.  There is no wiring or connections.  When you brake going down a hill it charges the batteries, and as you pedal going up a hill it automatically  turns the motor on.  Easy installation, easy riding.

It is very similar to MIT's Copenhagen wheel, which should have been on the market by now because they had a couple year lead on the FlyKly.  They licensed it to Ducati in Italy.
Update December 9, 2013- The Copenhagen wheel is available for preorder for $699.  While it appears to have a gear drive motor which will increase it's power up hills, it doesn't have a very big battery pack and will probably not have the reserves for very many hills.  There would probably be an overheating problem on a long climb anyhow, because larger hub motors, like the one on the cargo bike, can overheat with a larger load, and they are much more open to the air for cooling.  The spokes might also have a long term tension problem, as they are bent in a U which is more likely to move.  The torque arm in the earlier pictures appears to be removed, signifying light duty use.  It is possible to buy a kit with a slightly stronger hub motor with a larger battery mounted under a rear rack on eBay for less money.  Most of the FlyKly comments below will apply. The preorder website with more information is:

The devil can be in the details.

The motor fits in one side of the hub limiting it's size, they state it is 250 watts.

The batteries fit in the other side, and appear to be 20 cells in most of the pictures.  If they are:
-LiMn 18650 cells, they will have a capacity of 80-100 watt hours
-LiCo 18650 cells would be 158-198 watt hours
-LiMn 26650 cells would be 211 watt hours

For comparison, most ebike kits on the internet have a 300-500 watt motor, and the battery packs are about 36 volts x 9 amp hours, or 324 watt hours.

My Bakfiets solar electric cargo bike was designed to carry loads, and has a motor running at 500 watts, with 720 watt hours of battery capacity.

I'm going to quote electricbike.com, in a review they did about the Daimler (Mercedes Benz) Smart eBike:
"Smart bike has taken a big step into the electric bike market and "looks" to be trying to hit it out of the park with it's line of new ebikes.  However because they have chosen a 250 watt hub motor, their attempt looks like it will be more like a bunt-dash to first base rather than a home run."
(The whole report is at  http://www.electricbike.com/smart/  )

A further indication that the FlyKly is lighter duty is that they do not have a torque arm on the spindle of the hub, and rely only on the slots of the drop out to keep the axle from spinning.

Having only one speed is not that much of a handicap on an electric bike, I ride the solar electric cargo bike in top gear 98% of the time.  The motor does has to be functioning to make this possible, which means the batteries have to be charged.  A good analysis of the amount of energy available from regenerative braking on a bicycle is at:
Most riders should expect to get the majority of energy into the FlyKly batteries from plugging it into the wall, and then because the batteries have at most a 200 watt hour capacity, to have a limited to medium range (depending on individual circumstances).

A further complication is that regeneration will only work with a motor that is constantly engaged, there can't be any slip clutches that allow coasting.  The problem with direct drive bike motors is that the permanent magnets are constantly attracted to the steel poles for the windings, and this causes a slight drag when turning the motor, like riding with a soft tire.   If you have ever turned a stepper motor, (commonly used in computer printers, mechanical control systems, and small industrial drives), by hand, you have felt the cogging as the magnets jump from one pole to the next.  The result is that you cannot truly coast with a direct drive motor, when a rider stops pedaling there is a slight drag slowing the bike down.  A compromise is designing the system to have the motor turned on slightly to give the illusion of coasting, but this becomes a tradeoff between range and whatever regeneration might be produced.

I would point out two other limitations:
-Most bikes nowadays are not designed to adjust chain tension, that function being taken over by the derailleur mechanism.  In most cases the FlyKly chain will simply have a large droop and a lot of free play in the pedals, but in the worst case the chain may slip.
-Wifi or Bluetooth communications generally have a range of 300 feet under perfect conditions, and 100 feet or less under real world conditions.  This may affect the security functions of the FlyKly.

With the understanding of these FlyKly limitations I would still say there is a market for it, just don't expect it to haul loads up a hill.  If you are a lightly loaded bicyclist, who has a mainly level route, that is medium distance or less, and needs just a little extra help getting up that hill or two, this might be an easy to use solution for you.

Monday, November 18, 2013

The frame

Bicycle frames have evolved over 200 years, and there isn't much I'm going to do in my workshop to improve them.  A thin wall steel tube frame is probably the best choice for a cargo bike anyhow, as it won't fracture or splinter like carbon or wood when the bike gets dropped down some stairs, and is more easily repairable or modified than aluminum.  (I've seen projects that I've built a year or two after they were finished, and sometimes I've wondered "How on earth did this happen???")  Steel can take some abuse, which is good for a working bike that is carrying someone at 20 mph with no routine maintenance plan.

In general the walls of the bike frames I cut apart were about 1/16" thickness (0.060"), and they had a bead running down the inside of the seam, so they were not Drawn Over Mandrel (DOM).  Many bike frames are made of chrome moly (CrMo) steel, which is stronger than more common carbon steel.  (The tensile/yield properties for CrMo are around 70,000 to 85,000 psi, whereas 1020 is more like 45,000 to 60,000.)  However CrMo is slightly more likely to crack around welds, and isn't as workable.  So I used a good carbon steel and sized the tube slightly larger to make up for the psi.  It's a few ounces heavier, which will be more of a concern several bikes from now.

Down tube (behind front wheel), in jig ready for welding

One of the nice things about making a frame is that it can be made to suit the job better.  For example I used a 69 degree angle on the front fork stem, which gives slightly slower steering than most bikes, making the cargo bike more stable.  Also I dropped the crank as far as possible, to make it easier for riders to step through, or to stop and stand at an intersection.

MIG welding was used, which is not as pretty as TIG, but still serviceable.  My opinion here (Warning!) is that since abrupt changes in section create stress risers, the many ridges going across a TIG weld aren't as good as a smoother MIG weld, and the reason why either works is because the root section is so thick the stress risers don't matter.

I'm off grid, and the welding was solar powered.

The finished frame getting a coat of paint.

The frame, box, and lid were built concurrently, to make sure they fit together.  Porsche has been using water based paints on it's cars for several years now, so I wanted to try something other than the usual automotive spray cans.  Latex generally is too soft, so I tried to find some water based polyurethane at first, but it doesn't seem to be available anymore.  The final choice was a high gloss brush on exterior acrylic latex.  It works well, with some caveats:
-A good primer coat is needed or the steel will rust and turn the paint brown.
-Good prep work is needed for a good primer coat.
-It takes at least two months to dry.  The frame can be worked on the next day if you treat it very, very carefully, but it won't be hard.
-As it dries the brush strokes flatten out, and well brushed sections can turn out like automotive paint.
I'm planning on continuing to use paint like this, and improve the application technique.  A further experiment will be a clear topcoat, but that will require scheduling so that the first coat can dry thoroughly.