Monday, June 15, 2015

eCargo Bikes 101

Three months ago I put together a general introduction to my bikes for Drive Electric Vermont, the state agency responsible for implementing electric vehicle infrastructure and getting EV info out to people.  It was an overall view, with just a small amount of tech details to help people put the ideas into context.  Last month I repeated it for the Norman Williams public library in Woodstock, so I've decided to post a written version here for people to refer to.  These slides have a lot of info (you can click on them to expand them for reading), but I've added captions to help explain them.

Around 2010 I decided that I seriously wanted to use my car less, and in my rural area a bike seemed like the best alternative.  However I needed to cover distance while carrying loads, there are many hills, and I am only in average physical shape.  I built the first two solar electric cargo bikes shown above, and it became a large experiment that I shared with people around me as I participated in my town energy committee and Sierra Club activities.  Building is relatively easy for me as I've been doing it all my life- I grew up on an apple orchard and when I was nine I put a lawn mower engine on my sister's bike using scrap equipment parts.  Fortunately electric drives have become very good since then.

The first two bikes have worked quite well, and since the presentation 3 months ago have traveled several hundred miles and a few dozen test rides more than shown in the slide above.  I'm now building a third bike with a mid cargo box and mid motor, which should arrange the motor and battery layout nicely.  It will also be able to shift down for hill climbing, and it will have a lower seating position.  A fourth bike is being planned with more bodywork for both weather protection and fitting more solar power.

This slide shows some examples of  electric cargo bikes in use.  My Longtail is shown in the upper left with a 92 pound load, that I rode 11 miles to home using 4 cents worth of electricity.  I've also often ridden 45 to 50 miles (round trip) in street clothes to meetings on it without sweating.  In the upper center, the German utility company E.ON has a fleet of 6 eBikes for use, and they came out with a couple of Bakfiets with solar panels on the top a month or two after mine, so I like to joke that they copied me.  Upper right- I loaned the Bakfiets to the Bellows Falls Community Bike Project for a couple weeks last summer, and Bonnie took a day trip picking blueberries and visiting local farms, she simply put a large foam cooler inside the cargo box for keeping the food cool.  The lower left shows a mailman for the German postal service- they have several versions of eBikes.  UPS, Fedex, and DHL also all have cargo trikes for delivery in urban European locations, which are often faster than a delivery van driving through traffic.  In the lower middle is a family with kid's stuff in the pannier bags, and lower right is a vending bike for a craft beer company.

The rider on the E.ON Bakfiets is probably in good condition, but for all the rest of the riders the electric assist makes the difference between using a bike to carry heavy loads or not.


The table across the top of this slide shows the basic types of motors.  From left to right-  my Longtail has a direct drive hub motor (the motor case is the wheel hub), which is best suited for faster speeds and can regenerate electricity for recharging the battery when braking.  My Bakfiets has a geared hub, (with a smaller motor inside the hub that spins fast and uses gears to slow down the speed to connect to the wheel), which is slightly better (10% - 20%) for hill climbing than the direct drive hub, but can not do regeneration because of the slip clutch necessary for the gears.  All in one or add on wheels like the Flykly and Copenhagen wheel are geared hubs, and in general are weaker versions because the motor and batteries are all packed in the hub so they have to be smaller.  Their motor strength and heat dissipation will most likely be a problem on hills in my area, the all in one hubs are better suited for commuter runs in flatter terrain.  The last type of motor is connected to the chain, not the wheel, and this allows down shifting the bike for climbing hills, as well as getting by with a smaller motor (many European countries have a 250W motor limit).  It also allows fitting outrageously big motors for racing, but these usually have to be connected to the rear wheel with a separate left side chain, because the standard bicycle chain and derailleurs can handle only 500W to 1000W before they start to wear out quickly.

Having said that direct drive hubs are better for speed and geared hubs are better for hill climbing, I'll contradict that by saying I've ridden my longtail with direct drive up Mt Washington- but it wasn't easy! (left lower picture).  A direct drive was also the fastest bike up Pikes Peak a year ago  In this instance they dumped a lot of energy through the motor, and since the motor case is the hub it could dissipate the heat and not burn up, which is more of a problem with a geared hub motor that is sealed inside the hub.

The solar panel output on the bikes varies widely depending on weather, trees along the route, how long I park in sunny parking lots while stopped, etc, but it has generally been running from 25% to 40% of the energy needed during a trip.  In contrast I've been getting 1% to 6% back from regen.  I also sometimes leave the bike out in the driveway for the rest of the day when I get home, and find the battery is often fully charged when I bring it in.

The lower right photo is around the fourth version of Luke "Live for Physics" "Death Bike", which can run through a standing start quarter mile in 11.5 seconds at 110.6 mph.  Speed is not a problem for an eBike, but there is a trade off between speed and range.  Luke's bike is fast, but probably cannot travel more than a mile or two at speed.  This is a mid motor setup, and has the separate chain for connecting the motor to the rear wheel.  A mid motor can allow special gearing, unusual motor sizes (Luke is probably feeding 100 kW through this motor for a few seconds), and better cooling than a hub.  The name "Death Bike" is from the earlier versions, which had a tendency to launch unwary riders air born.  The rider in the photo is actually Stephane Melancon, who rode his electric motorcycle from Montreal to Mt Washington, where I had the chance to talk with him a bit.

On the left in this slide are the two types of controls used on eBikes.  Some bikes use a hand control such as a thumb switch or grip that twists to turn on the motor, others are connected to pedal switches, known as Pedelec systems.  The Pedelec comes in two varieties- a sensor that looks for rotation of the pedals (cadence or motion sensor), or a sensor that monitors the pressure on the pedals.  I slightly prefer the hand control because it makes starting with a load much easier to balance, but the Pedelec is legally required by most European countries. The pedelec pressure system is almost as good as a hand control, but the rotation sensor method often takes one half to two pedal rotations before it will turn on.

On the right of this slide- often times dealers will list a battery as "7 Amp hours", but Ah isn't the whole story for battery capacity.  You are looking for Watt hours when comparing systems, which is Amp hours times the battery Voltage.  For current eBikes a small battery is around 7 Ah x 36 V = 252 Wh, or about 1/4 of a kiloWatt hour (the same unit as on your home electric bill).  A large battery might be 20 Ah x 48 V = 960 Wh, or about one kWh.  Batteries are made of many smaller cells, with the round 18650 cell (18 mm diameter by 65 mm long) being more common because they are made by the billions for laptops and power tools, and are less expensive ($290 per kWh average price in 2014).  I'm using the flat pouch prismatic (rectangular form) cells in my bikes because they pack better, I'm not concerned about cooling because the battery is oversized (to allow me long distance riding), and the safer LiFePO4 chemistry that I like is common in pouch cells.  However each time I've ordered a battery (from China), it's been about $475 per kWh, and it disappears into China post for about 15 weeks and then shows up looking like the box was rolled and crushed,  The batteries have worked fine, but if Tesla makes their cells from the new Nevada factory available to builders like me, I'd gladly switch to paying $185 per kWh less and a 2 week delivery.


Our culture is built around the car, and our highway budgets are mostly car dollars.  Besides the general public test rides and talks I've been giving, I think it's important to reach out to planners and government people also.  Dave Cohen in Brattleboro has been trying to build a fleet of Cargo eBikes that can be loaned out to energy committees and bike shops around the state, (see www.vbikesolutions.org), but establishing the need for them, planning for biking systems, and funding are the usual problems.  To prepare for this my Longtail is currently (June 2015) up in Montpelier in a 30 day pilot study for the VT AOT program Go!Vermont.  This slide is a screenshot of data from a test ride I took through the capitol on February 4 for the study, (during very bad weather with 3" of snow on the road- the bike was a slush ball at the end).  My bikes have Cycle Analyst data recorders that measure electrical use and GPS location so that it can be analyzed.  You can see the trip was 4.27 miles and took 16 minutes and 45 seconds, or basically just like a car.  It had an unusually high energy consumption of 20.8 Watt hours (Wh) per mile, (which I think was primarily due to the snow and slush, and second to the temperature of 14 F), which gives a total of 89 Wh (or 1.5 cents) of electricity for the trip.  (Using a plug in charger that is 85% efficient instead of the built in solar panel, the electricity needed is about 110 Wh, or 1.8 cents.)  I've positioned the cursor at one of the peak speeds on the graph for reading the other selected measurements at that moment.  You can see that my average speed was 15.29 mph, and peak was 27.5 mph.

I've found 99% of Vermont drivers to be considerate of me on the road, with some of them going way out of their way to give me space on the road.  (I think this is because after a few winters here, you learn that if you think of the road as a race track you can get in big trouble.)  However the way our roads were built was meant for cars, and it is hard to create new traffic flow habits.  In all the major cities in Vermont I've found it easier to ride in the car lane at the 25 mph speed limit, then to try to ride slower next to parked cars and causing a traffic block.  Burlington is a special case because they have installed some bike lanes, and using them (even going uphill) I found biking to be faster than the cars.  Despite these results, the general reaction by a car driver to my bike is to try to pass.  (One example that stands out was a pathetic small sedan in Brattleboro going uphill, the driver was flogging the car for all it was worth.)  Rutland also tried to install bike lanes along Route 4 going east, but the merchant push back grew into a nasty political battle and they had to be removed, despite several studies that have shown increased business volume resulting from bike lanes.

In the lower left in this slide I snuck in my off topic wish list of projects for general biking safety in Vermont, in order of priority:
-Training- riders and drivers need to know their space on the road and how to act, as it is a public commons.
-We really need to spend more dollars on bike (and pedestrian) infrastructure and less on cars, such as wider road shoulders in rural areas, and Intermodal transportation systems that can carry bikes easily.
-Appropriate speed, since just like cars, bikes can travel too fast and get in trouble.
-Critical mass is when enough bikes are on the road that they are common and drivers expect them.
-Riders should stay aware, since riding a bike is so much fun that it is easy to get blissed out.
-Other programs- two of the main supporters of the Complete Streets legislation during it's passage into VT law a few years ago were AARP and parts of the VT Department of Health, but not so much transportation people.  There are known health benefits to biking and walking- it has been shown that the benefit of biking to a person's health is about 20 times greater than the risk.  These benefits should be promoted, as well as programs that enable people to bike or walk.
-Vision Zero is a program that started in Sweden, and has been taken up by NYC and California.  It is about using the design of roads to prevent accidents, with the goal that no one should get hurt just from traveling from point A to point B.


Since eBikes can be built to travel at motorcycle speeds, it's necessary to artificially set the maximum speed.  Some of the guidelines I'm using to build my bikes are shown in this slide.  For context I would like to point out that in real life it is difficult to enforce these rules, not just because many bikes lack speedometers, but also because regular bikes are capable of 25 to 30 mph with only human power (the human powered bike record is 83 mph), and I've reached 46 mph coasting downhill (with no motor power) on both of my bikes.

The most universal rule is the Federal limit of 20 mph under test conditions, but it is a Consumer Product Safety Act, and applies only to the first sale, i.e. from a manufacturer to first purchaser.  The state laws are a little more explicit, with a maximum speed around 20 to 30 mph, but some details such as motor only, or motor and pedaling together, are often missing.  Sometimes the vehicle classification is vague too, for example the NYC bike messengers did such a bad job of using electric bikes that they got them banned (although vendors and delivery bikes still seem to be using them), and this spilled over to a legal quandary for the rest of the state that needs an act of the legislature to assign a vehicle category to eBikes.  Vermont is generous with a 30 mph and 2 HP limit, but it is my guess that this law is from the 1960's when putting a small 2 cycle gas engine on your bike was popular.  Some interpretations of VT law use this rule to find that a license is required, others treat eBikes as bikes and it is not.  My bikes are set up for the Federal 20 mph under motor power only rule, but they do not turn the motor off when pedaling above that speed (such as California requires).  I think this is a good compromise, because I can fairly easily reach 25 mph to make it practical to travel between towns, or flow with downtown traffic.  Justin Lemire-Elmore (eBike innovator) has also stated that 40 kph (24.9 mph) is a comfortable cruising speed.

At the bottom is a typical graph of the physical limits I've also considered, the bike/ped curve is on the left in red.  This is of fatality risk versus collision speed, and you can see that up to about 15 mph the human body survives well, (which makes sense because we can run that fast).  Between 20 to 25 mph is a threshold where the risk starts to increase sharply, and I've set my design line just above that.  This keeps the eBike speeds mostly within normal bike range for infrastructure compatibility, and combined with bike component strength limits, car driver expectations, the practical need to cover distance, and enough power for hill climbing, seems a reasonable limit.

The League of American Bicyclists commissioned a survey to find out what most people think of eBikes.  In some areas, such as residential communities with bike paths, or National Parks with mountain bike single track trails, the speed of an eBike has shown up as a conflict between different users.  The first four bikes on this chart look normal and have lower power, and most people felt they were a bike.  (As Luke "Live for Physics" has said, "If it looks like a bike and it acts like a bike, then it is a bike.")  However starting with the large enclosed trike, and including a 40 mph and 50 mph bike (i.e. motor power only on level road), as well as the eScooter with minimally functioning pedals, most people felt they were not bicycles.  These opinions fit well with most bicycle infrastructure goals, however there is an obvious problem with urban delivery bicycles and trikes.

While there is a fairly vocal faction of bicycle purists that have been calling for eBikes to be banned from paths or MTB trails, this does not represent a larger group of people with physical impairments, for whom eBikes would make the path or trail accessible.


To sum up the benefits of an electric cargo bike, the main benefits would be better health, connection to the world around you, saving money, and much better for the environment than a car.  The graph shown above is from a Drive Electric Vermont presentation by Dave Roberts, and illustrates the amount of energy used by different vehicles, bicycles are the tiny bar at the bottom.

Using my energy use figures in the center of this slide to figure out range:
-If you have a small battery, don't pedal, and drive fast, it would be 250 Wh divided by 25 Wh/m, or 10 miles.
-If you have a large battery and pedal along slowly, it would be 960 Wh divided by 10.5 Wh/m, or 90 miles.

I know many people can not imagine biking in the winter, so I've added the pictures on the right.  At the top is Eric Larsen riding around the Artic, next is a Bakfiets being used to haul ski boards around a ski area for classes, then another Bakfiets pulling the kids along a snow covered street, and at the bottom is Maria Leijerstam on her trike at the South Pole.  Vermont has a very strong winter sports culture, and it is only a small step to include biking.


This last slide is from the Bicycling Without Ages program, which is in many cities around the world.  This is from Oslo, Norway, a climate known more for cold than being tropical, but where biking is still common.  If you look close at the four trikes that are carrying seniors, you can see battery packs under the rear racks and a motor in the rear wheel.  (There are also perhaps 20 other bike riders following them.)   Bicycles are very valid solution for many purposes, and the main problem we have with them here in the U.S. car culture is that we have forgotten how to use them.  Electric bikes with better bike infrastructure are a serious car substitute.



Sunday, January 25, 2015

Bicycle tire hydroplaning test from Mt Ascutney STAB

There has been a lot of water under the bridge since my last post, and I'm almost ready to write again.  In the meantime here is a short clip from my neighbors in the next town over.  The Mt Ascutney ski area has been closed for a year now, but people in town have been developing a good mountain bike singletrack network since 2007.  You can find more info about them at:
-Ascutney Trails, the webpage for information about the trails
-Sports Trails of Ascutney Basin (STAB) facebook page, the group that maintains the trails
-Vermont 50 mile mountain bike and ultra run race, a yearly race that benefits the Vermont Adaptive Ski and Sports Foundation

Not all of us are into Solar Electric Cargo Bikes.  They posted a video from an Ontario shop doing some fat bike tire hydroplaning testing last month.   I should mention that a regular bike on the street can not hydroplane...


Thursday, October 23, 2014

Oct/Nov news + REV conference

The solar electric cargo bikes have been rolling nonstop.  Although I have notes for 21 more blog entries, things have gone a little over the top and I haven't had a couple of days to write a good post.  The motor for the third bike has also arrived and I wish to spend time modifying it, so I'm going to try something unusual here and let other people write for me this time.

(Update added November 24):  One more press article- The Longtail was down at the Brattleboro EV event, and Jan Lambert mentioned it in a short article in November issue of The Valley Green Journal.  The issue can be read here:  http://www.valleygreenjournal.com/current-issue-and-archives/

(Second Update added November 26, and then I'll get back to finishing "Building the Longtail 3/3");  The region where I live is a section of the Connecticut River Valley.  Although the Vermont and New Hampshire state border runs through the middle, it still functions as one single population center and ecoshed.  An example is our Sierra Club Upper Valley Group, and I've been appointed to be one of the alternates that represent the group during meetings of the SC Vermont Chapter:
At the UVSC autumn social, Norwich, VT,  Photo credit:  Robb Kidd

I am finding that building the bikes is relatively easy for me, but then there are cargo bike loads of public relations and education that have to happen.  At least some of it is enjoyable- a.k.a. "a bike ride"- with stops along the way for questions.

Earlier in October Katy Savage wrote a nice article about the bikes in the Woodstock Vermont Standard newspaper, you can read it here:  http://www.thevermontstandard.com/2014/10/karl-kemnitzer-inventors-bikes-see-the-light/

My display booth at the REV annual conference.

The bikes went up to the annual Renewable Energy Vermont conference (http://www.revconference.org/) in Burlington for October 16-17, and were displayed alongside 38 other companies, from small solar, geothermal, and legal companies up to UVM, Stiebel Eltron, Gro Solar, and Hydro Quebec.  I had a great time, with dozens of cross discipline conversations and spreading ideas about renewable energy and alternative transportation options.  One high school teacher may build a bike as part of a Science, Technology, Engineering, and Math (STEM) class curriculum.  I also attended one presentation session about the Problems and Risks of Renewable Energy, which was devoted entirely to financial, insurance, and banking concerns.  It's been my belief that the chance the sun will come up tomorrow is a safer bet than the price of oil next week, but oh my word now I'm not so sure...

The Burlington Free Press wrote a nice article about the conference and the bikes, which you can read here:  http://www.burlingtonfreepress.com/story/life/green-mountain/2014/10/16/solar-bike-builder-charges-ahead/17372883/

The Seven Days newspaper also did a short article:  http://www.sevendaysvt.com/OffMessage/archives/2014/10/16/renewable-energy-conference-draws-hundreds

After the conference was over, I rode down to the center of Burlington to take part in an alternative transportation exhibit:
Lineup of Cargo Bikes on Church St, with reclaimed cooking oil truck
in back, and electric cars and natural gas garbage truck across street.

The ride back from Church street went uphill from Lake Champlain, around UVM, to the conference building.  Normally I find that I can keep up with traffic on an urban street, but this time the bike was faster than traffic because of the bike lane.  In between traffic lights our speed was the same, but at each light I was able to ride up to the stop line, thus gaining 3 or 4 cars each time.  Another recent commuter test across the Connecticut river from Norwich to Hanover by Vital Communities gave similar results:  the bikes took 9 minutes, the bus took 11.5, and the cars in the test took 20 and 30 minutes from start to parked.  (Link to article:  And-the-bikes-win! )

I've also attended an Upper Valley Transportation Alliance meeting, and learned about the latest work being done on the Lebanon to West Leb (New Hampshire) rail trail.  It's the only slow speed connector route in that transportation corridor, so the plans are to make it suitable for bike commuting.  Part of the plan includes snow plowing only half of the path for bikes, so that skiers and sleds can use the other half.  Now that I'm designing the third bike, I'm starting to pay more attention to fenders and weather shields for year round bike use, so I'd like to end this post with one more link, to a blog about bicycling during winter in Oulu, Finland:   http://wintercyclingblog.org/2014/10/17/oulu-finland-winter-cycling-capital-of-the-world/

Friday, October 3, 2014

Mt Washington

The ALT Energy Summit (http://altenergysummit.org/) alternative vehicle climb at Mt Washington was held on September 13/14.  The mountain road starts at 1565' elevation, runs 7.847 miles up to about 6200' at the parking lot (the summit is 6288'), and has historically been used as a test of vehicles- the first motor vehicle to go up was a steam powered Stanley Locomobile in 1899.  After a lapse of the event for several years, Ted Dillard, (President of the Boston Chapter of the  Electric Auto Association), wanted an excuse to run his electric motorcycle up the road and revived it.  He secured sponsorship from the local utility- NH Electric Coop- and organized a Summit last year.  I had debated whether to attend, and later regretted not going because Michael Corbin brought his Sparrow electric auto.  Michael had lived two houses up from me when I was a teenager in 1970's Connecticut, and made Corbin Gentry motorcycle saddles in the old mill in town.  He also had an orange fiberglass bodied Phaeton with a VW motor, and at the time I had just started to put Porsche 356 motors into a VW bug and a Karmann Ghia, so it would have been nice to finally connect.  Unfortunately he didn't attend this year, but it's interesting that we have both moved towards electric.

Since Ted had graciously taken part in the Upper Valley Electric Vehicle Forum and Demo last May, it gave me a push to attend the Summit this year.  I also wanted to display Sierra Club information because of their sponsorship (along with Plug in America and the Electric Auto Association) of National EV Week (https://driveelectricweek.org/).  Although I would be out riding the Longtail up the mountain, Dolores Rebolledo of the NH Department of Environmental Services had a table next to mine, and was able to answer questions.
Mt Washington is known for it's bad weather, and there were
clouds around the summit when I arrived...

I had designed the solar electric cargo bikes to cover ground between towns, so I knew that hill climbing was not their strength.  The Longtail also has a direct drive hub motor, which really isn't the best for hills.  My game plan was to get off for the very steep parts, and walk along with the bike turned on low.  (My bikes have a speed control on the grips, not pedelec control.)  Based on hills around my house the climb seemed very possible but slow, and a major goal was to not burn out the motor or it's controller and get too expensive.  It was also encouraging that another (highly modified) direct drive bike had not only climbed Pike's Peak but had third fastest time, an article with some details is at:    http://www.electricbike.com/pikes-peak/

Inside the base tent- my Upper Valley Sierra Club display was on the far table.
Directly behind me was Chargepoint EV charging stations, and
Dolores Rebolledo of the NH Dept of Environmental Services,
Other displays were from sponsor NH Electric Coop,
Dragonfly Aerials, National Electric Drag Racing Association,
and Mohawk electric mowers.  When it started  raining later
the vehicles were moved inside around the edges of the tent.

In addition to several Teslas, there were two race cars from Entropy Racing,
an electric Cobra, a Fiskar Karma, and a Mercedes converted to a grease wagon.

Dartmouth brought their Formula race car up, and there were
EV team members from Olin and MIT.  Photo credit: Benswing Rich

A cute little kart with an ETEK motor.  Nicely done layout, with huge fins on the
motor controller.  I'm not sure why a main contactor is mounted on the steering though.

Dr Bass of the Endless Sphere forum rode his Zero to the event.  Notice the
panniers on both his and Benswing Rich's bikes that are packed with extra batteries,
and also upgraded chargers to make long distance travel more feasible.
To make a long trip like this, Dr Bass showed me a route map he creates
with software that lists the details of charging stations along the way.

The RooPod with both hatches open, and in behind it is a Dirigocar,
and then a Ford Fusion Energi.  These are internal combustion engine cars.

Bikes included two Outriders, as well as eVelos, and a RANS recumbent.

Heat management is an important consideration when pushing design limits.  I did a dozen runs up a 12% slope, 1.25 mile long hill near my house with an infrared thermometer in hand to prepare for the Summit.  On one sunny day the controller peaked out around 119 degrees F- hotter than I like but within limits. (I use the "too hot to touch is too hot" rule for electronics.)  I then modified the Longtail by adding a sheet metal bracket that moved the controller out into the air flow.  One of the Outriders pictured above had it's motor overheat at mile 3, and unlike my Longtail they didn't have the option of getting off and walking alongside, so rather than burn it out the owner decided to coast back down.  (The trikes that climbed Pike's Peak had custom cooling fans.)  I'm trying to decide how to cool the mid motor on the third bike, because long before the electrical insulation catches on fire the permanent magnets start to degrade.  At the moment I'm thinking of a small fan on the outboard end of the shaft (away from the drive sprockets), with small holes in the motor casing for air flow.  If moisture turns out to be a problem, the holes could be sealed, and then the motor would become a regular TEFC (Totally Enclosed Fan Cooled) frame style.  An advantage of a hub motor over an RC (Radio Controlled) type motor is the larger surface area, (most of the time only the frequency of magnetic transitions is considered).

This is what a mid motor kit looks like on a recumbent.  John Anderson 
(see Yahoo groups: power assist) added a Cyclone RC type motor with
planetary first stage speed reduction to his RANS, and fed the power
into a large fourth front sprocket riding on a crank freewheel.
This was the fastest bike of the day, however I would have some
reservations about building this and selling it to the general public,
as an unskilled mechanic could easily mess this up.

Randy Bryan had his Prius generator conversion display, and the 
next display over was about weatherization and energy efficiency.

The climb turned out to be reasonable, not as steep as I had imagined, just much longer than the climbs on my errand runs.  There are actually two 500' long sections of my town road that are steeper.  Of the 7.8 miles, I ended up walking the Longtail for about 2.  My original plan was to stop every mile and measure the temperature of the motor and controller, but they never got above lukewarm (~80F) so I didn't bother after the first few times.  Part of the reason they stayed cool was the weather- the top third of the ride was 30 degrees F, with a 36 mph headwind (gusting to 42), and no solar heating (i.e. in the clouds).  Another reason was that I was favoring the motor to prevent burning it out, but a large third reason they stayed cool was that the motor controller cut back on the energy it was delivering.  I'll write a blog post about electric motor voltage (Kv), efficiency, rpm, and work, but for here the short explanation is that electric motors are sensitive to rpm just like a gas engine, and neither likes being lugged at a slow speed.  It's true that at stall an electric motor develops it's greatest torque, but because the shaft isn't spinning all the energy going into the motor is coming out as heat, not as work.  At low motor rpm's, there is a large amount of slip in a motor's field between the magnets and coils as it approaches the stalling condition, and the motor controller on my bikes (Infineon EB3xx series chip) reduces the current.  (I have not studied the algorithms yet, only a program that allows me to reset some of the controller parameters.)  I had noticed this effect occasionally for a few seconds during regular errand runs:  At speed (20 mph) going up a slope the motor would be running around 700 to 750 watts with peaks around 800 w, but as the bike slowed down (on the same slope) the wattage would drop (due to amps, not battery voltage sag).  During the sustained climb up Mt Washington at 3 to 9 mph much of the ride was around 480 watts, sometimes dipping to 340.  I could try to remedy this by resetting the controller amp limits, but the motor would still be running at a less efficient slow speed.  I've noticed a Chinese company that is now building a two speed geared hub bike motor, and a few companies that have also started offering gearboxes (often having only 2 speeds) for electric vehicles that need a wider speed range.  For an EV under average use a gearbox is just added weight, expense, and something else to break down.  As an example the first Tesla model had a two speed gearbox, which was discontinued.  However under extreme situations the lack of low rpm performance can be noticed:

Luke Live for Physics's Death Bike racing a Tesla S
Neither of these vehicles has a gearbox, but the extra mass of the Tesla accentuates the low rpm problem.  For the third bike I'm planning on using the derailleur system to allow the motor to be shifted, and the question isn't so much the benefits of shifting down, but more of how long a shifting mechanism and chain will last at 700 watts.

The road up Mt Washington is a medium width tar road for the first 5.5 miles, switching to dirt for one mile, and then back to tar at the top.  I didn't take pictures on the way up, and am going to use a video from Entropy Racing to show you what it looks like, (notice the first 15 seconds as the motor speed gradually increases to a more efficient rpm range):

The EVSR car reaches the top in 7 minutes, 28 seconds, or around 60 mph. My time was 1hr 31min 31sec, which is OK- faster than walking, but since the record time for a bike is 49 minutes, there is definitely room for improvement.  In all fairness it should be noted that that I was able to get off the bike at the top and walk around looking at the views like a normal tourist and then ride down, whereas I've been told by a person who has been a pit crew for a bike racer that their job was basically to scrape the racer up off the pavement at the end and ferry them back down.

The summit building with a cog railway train approaching.

The four eBikes that made it to the top during the ALT Energy Summit (l to r):
-John Anderson, riding a RANS recumbent with Cyclone mid motor kit
-Larry Gilbert and coworker of Zoombikes riding eVelos
-Me with the solar electric longtail cargo bike

A closeup of the Longtail at the top.  I need to get the rear panniers finished,
they would have looked nicer for a photo than a shopping bag.  If you click
on the photo you can see the infrared thermometer in the front basket.

The cairn at the very top of the mountain (6288'), with people having their picture taken.

There were at least 200 people hanging out in the summit lodge.  This photo
is blurry because of the high indoor humidity condensing on my cold camera lens.
The building is built for severe weather and has an extremely tight envelope.

Looking down from the summit area to the parking lots, with the Longtail
at the base of the stairs.  It was neat watching the clouds move by,
very much like ocean waves rolling over and around nearby mountains.

Gazing down into the deep blue depths of the ocean.

After looking around for awhile, it was time to head back down,
especially since Ted had asked us to be back for an exhibition period.
It was just as well, because shortly after the weather turned to freezing rain.

3/4's of the way down I stopped to take a picture of a row of knobs with a very deep
valley between me and them.  However the wind was probably around 45 mph,
and I had a hard time standing on the edge and holding the camera steady.

There were some fantastic rock formations,

About half way down I realized that I was looking down
at a ski area  under the clouds.

The Longtail used 670.97 Wh of electricity on the way up, giving 86.4 Wh per mile, at an average speed of 5.14 mph.  This is one of the worst fuel mileages I've seen, similar to the other end of my road.  Coasting back down I turned on regeneration and had a pleasant, leisurely ride looking at the scenery.  Regen put 151 Wh, or 22.5% of the energy back into the battery, reducing trip energy use to 35.2 Wh/m, however a second glitch in the electronics showed up.  After a few minutes of regen around 320 watts (15-16 mph), it turned off, and after I slowed down it turned back on again.  The controller was cold, so my best guess was that the battery voltage rose above the upper limit, and the Battery Management System (BMS) shut off.  I rode the rest of the way down using the brakes occasionally to hold the speed down to 200 watts (10-12 mph), (and also pedaling on the more moderate declines to keep the regen up), and the regen stayed on,  At this point I don't think regen is all that helpful on a bike.  During the last summer it has usually returned only 0.5 to 4% on my longer trips, and the only large regeneration happens for short time periods down one or two hills on my routes.  It's best use seems to be a substitute for braking, but even then I haven't used it much- if I am coasting 15-25 mph down a hill I prefer to stay at that speed and cover ground, I've mostly turned it on above 25 mph for only brief periods of time.  The solar panels are usually several times more productive (20-40% generation of load).

For comparison:
-John Anderson used 750 Wh on his RANS recumbent, at an average speed of 7.1 mph, (showing the advantage of using gearing to keep the motor rpm higher).
-Dr Bass commented that his 2012 Zero S, modified with a 2013 motor and ZF15 equivalent battery (13 kWh usable), with of total weight of 500 pounds, took 2071 Wh from start to the summit and got 800 Wh of regen on return.
-Ted Dillard had estimated about 2 kWh usage for his homebuilt electric motorcycle.
-Tim Letourneau commented that the Ford Fusion Energi regenerated about 6.92 kWh on the way back down from the summit, giving him a 91% charge on the battery.
-I heard anecdotally that last year a Tesla had regenerated about 60-65% of the energy used during the climb.

At the end of the climb after the group photo.  In behind my bike is
one of the Outrider trikes, the MIT 914 electric car conversion, and the
MIT trike with an Agnelli axial motor (see Cedric Lynch) and battery trailer,

Besides getting a better feel for designing a cargo bike for both distance and hill climbing, there were two other rewards for the day.  The first was that a picture of the Longtail got posted on the Tesla Motors Club forum: (http://www.teslamotorsclub.com/showthread.php/30898-2014-Mt-Washington-Trip/page4).  The second was that after pushing some limits climbing Mt Washington, the upper Connecticut river valley forests and hills were an indescribably beautiful trip home.

Monday, September 8, 2014

Cedar Circle Strawberry Festival 2014

On June 29, Cedar Circle organic farm held it's annual Strawberry Festival.  The farm is managed by Will Allen, (author of The War on Bugs) and Kate Duesterberg, who had put in a large roof top solar array on one of their barns several years ago, and are now arranging a community array along the Ag fields on the northern border in a buffer zone that cannot be farmed organically.

The strawberry fields along the Connecticut river.  Most of the displays,
tents, music, and food were behind me in the farm buildings up the hill.

I had taken part in the festival a couple times before, with a solar education display for Solar Hartland, and also with the Transition Town bicycle blender:

Farm Education Coordinator Cat playing music with the band at a previous
Berry Brunch in the Fields event while making a bicycle smoothie.

My display was on the border of the fields and buildings,
between the farm's electric tractor and Sun Common's booth.

Cedar Circle converted an old Allis Chalmers model G to electricity by replacing the gas engine with an electric motor.  It's turned out much nicer for the field crew planting and working alongside the tractor.  A problem has been the lead acid batteries.  I've read several times that lead acid batteries do not work well in an electric bike, simply because if they are discharged below half full the plates become sulfated quickly and ruin the battery.  Most people cannot stop using an eBike assist during a ride as long as the batteries have any charge left, with the result that generally lead acid batteries do not last a year.  After the festival we talked for awhile about the benefits of using lithium batteries (which can be drained almost to empty), and adding a few solar panels to the battery box cover.

I brought up the Bakfiets, along with the new glassless, frameless solar panel and some pictures of the Longtail.  It turned out to be a very cosmopolitan crowd, with 2 separate people telling me they had owned a Bakfiets (one in California, one in Amsterdam), and another young family who said that their Bakfiets was in storage in Chicago at the moment, awaiting shipment to Hanover.   They had been using it in Portland, Oregon on relatively flat terrain, and we talked about the process of adding an electric drive to make it more usable in this area.  Unfortunately there were no test rides, as there were too many people (1400) and little kids were running everywhere,  I also had my picture taken with 3 high school students from NYC!  They were looking for environmental projects to write about for a science class report.

There were 3 teams of draft horses giving alternative transportation
hay wagon rides, this team is Jim Fitch's from Cornish, NH,

A local theater group also had horses that the kids could get close to.

The bike parking area.  Cedar Circle offered free admission to the 
Festival for anyone arriving by bike or walking.  Hopefully this
will grow greatly in the next few years.


Saturday, August 23, 2014

Longtail construction (2/3) Rear rack

In the first post about building the Longtail frame, I covered extending the chain stays and putting in a platform for the battery box to sit on.  The next step was adding on the rear rack and then tying the top and bottom horizontal tubes together to form a truss structure.
After installing the wheels, the frame was propped up along a line drawn on a flat and level floor.  (You can do this work at any angle if you are willing to do a lot of measuring and calculating offsets, but it's much easier and more foolproof to just hold up a level.)  I used an oxy acetylene torch to heat the tubing while bending human friendly curved ends on the rack, as the radius was too tight for any cold bending forms I had available.  It was then rested on top of the battery box with 3/8" thick spacers to create space for a tie down rope to fit through, leveled, propped in place at the rear, and then notched to fit to the seat tube.  There are wedges centering the front of the tire in the chain stays so that the tire tracks straight, and the boards clamped on each side of the tire are the right width to hold the rear of the rack centered.  At this point the old seat stays are not connected to anything at the top.

The sequence for connecting the chain stays to the rack was based on working from the fixed point at the seat tube towards the tail end, and fixing any errors from welding heat warping as I went along:
1.  Tack weld the front of the rack to the seat tube to stop things from moving around.
2.  Cut and tack on uprights that just clear the back of the battery box.
3.  Readjust the rack to be square and level, and add diagonals from the drop outs to support the back of the rack.  The upper ends are notched as usual with a grinder to fit, but the lower ends were slit for an inch and squeezed in to make a taper on the tubing, and then hammered square to fit over the existing luggage rack mounts on the drop outs.
4.  At this point the assembly is starting to be self supporting, and cutting tools can now be used on the top of the old seat stays to fit them to a new cross stay inside the rack tubes.
5.  A diagonal is then run from the cross stay to the main chain stay junction.

All of the fitting work had to be done inside on the flat floor, which is OK for one project, but if I were going to build several bikes I'd make a table or jig in a better space or outside.  Each diagonal was briefly tack welded in place with many plywood shields around it to contain sparks, and when enough triangles had been formed to stabilize the structure it was moved outside for more complete welding.  Tack welding an assembly first also helps control warping from welding.

The cross stay that connects the top of the old seat stays to the rack tubes.
It also links to the diagonals running down to the chain stay extension junction,
and holds the rack tubes at the right width.

After making several mock ups, I decided that the board on top of the rack should be about 5" to 6" wide.  If it was wider the corners cut into the insides of a passenger's thighs, and if it was narrower it wasn't as useful for supporting a load.  Since standard 1"x 6" lumber is 5.5" wide, I used that width so it could be an option even though I planned on using thin plywood, as 5.5" would also allow strips to be cut from a sheet of plywood with a margin for a kerf but not too much waste.  The rack tubes are 5 5/8" wide, so that the tubes stick out 1/16" further than the plywood on each side to act as a rounded bumper.

With diagonals welded in to form triangles, the rear section of the frame was pretty stable, and I went back to finish up the front of the rack.  (Although some parts look yellow in this photo, there was no brazing, only welding.)  I added two strips for attaching the top of the battery box, and finished the seat tube welds.  Unfortunately the rack landed on the original seat tube exactly at the top, so I removed the old seat clamp lugs, and then welded a few inches from the top of another tube on top.  

I try to work as cold as I can to avoid changing the properties of the steel, while still achieving a good weld penetration.   But even though I also used a piece of aluminum tubing (it doesn't stick to a weld) inside the seat post to align the top extension, all the welding in this area deformed the seat tube enough that a seat post would not go in.  I don't have the proper size reamer to fit this bore, so I taped a 1" wide strip of coarse grit belt sander cloth on a 3/8" rod, wound it around to build up the width until it just fit inside the tube, and spun it with a drill for about 20 minutes inside the problem section to open it back up.

Looking at the rack attached to the lower chain stay assembly from the rear.

I prefer priming the work after I've finished a section, mainly because it splits hours of sanding and cleaning for paint preparation into smaller sessions, but also because it immediately protects the newly worked metal from oils and salt from my hands and dirt, so there is less prep needed.  With this method the primer needs only a light cleaning with a degreaser, a scuff sanding, and then a quick tack wipe when I'm ready to paint.  I've always preferred a self etching primer for automotive work as it adheres a bit better, but I found out on the Bakfiets that the chemicals in it do not work well with an acrylic latex top coat.  The water based paint reacted through the primer and rust spots bled through.  For this Longtail I used a regular plain lacquer style primer and had no problems.

A side view of the rack assembly.

The weak spot in this design is the hole for the battery box, as it has only a short height diagonal brace under it that lands in the center of a seat tube section.  However overall this design is overkill, as the loads in a truss are carried mainly in the top and bottom chords, which in this frame are well braced straight tubing spaced 17" tall.  To give you a rough idea of the strength, compare this to a 10" or 12" high floor joist in your house- the load carrying capacity of a beam increases proportionally to the square of the height.  Without considering the effect of width, a 17" high beam is 2.9 times stronger than a 10" high beam.  A stiffer frame will also give better handling (more precise steering).

Wednesday, August 6, 2014

The Strolling of the Heifers

The Strolling of the Heifers was founded in 2001 to benefit local food, farmers, and healthy agriculture.  It has grown over the years, and now has a Slow Living Summit to go with it.  Brattleboro cargo bike advocate Dave Cohen put out a call for cargo bikes for the parade, and I took the Bakfiets down to it.  A full range of bikes showed up, which included panniers, racks, trailers, trikes, longtails and bakfiets.  I tried to take some pictures while riding, but there is a more complete video of the parade on their website (the bikes are at minute 41). My overwhelming impression was amazement that so many people wanted to watch cows walk up main street.  Bikes are much faster.  But in keeping with the spirit of things, we rode at a heifer's pace, (which I think is just a little faster than the pace set by the preschoolers in my town's 4th of July parade).
I parked on the south side of town and rode in to the parade.  On the way I had to stop at the offices of Building Green, the energy efficiency building journal, next to the Estey organ museum, for a Green Photo.  The row of old mill buildings along the street all have slate siding.

This was our staging area, the hill in the background is across the river in NH.
(Click on pictures to enlarge.)

Among the bikes were Kathleen's trailer/canoe,

a local newspaper bike delivery service,

the frame of a new vendors cart bike being built by Hannah,

 and a nice cargo bike with a front box built by Jesse of Seneca Bicycle Works.

This is Todd's custom ebike with a 2 speed front hub, pulling a trailer.

The drive system of an Outrider trike in the parade.  Note there are only 3 large wires coming out of the motor, so there is no rotor position feedback.  This makes the motor harder to control and not as efficient, I'm in the middle of planning the motor and gearing for the third bike right now, and plan to cover this more in a future post.

Peter explaining his motor upgrade in his very dairy (decorated with cow spots) ELF.

Two Yuba el Mundos with a Stoke Monkey and a Bionx, and a passenger who is ready to ride.

Heading up Main Street.

Looking back down Main Street, (with 1/4 mile of people already).

Rolling UnThunder.  Quiet saves lives?

Stephan and Eliah in their Quadracycle.  Each rider was connected to one rear wheel,
with no link connecting the two sides.  Photo courtesy of Dave Cohen

My Bakfiets. The person riding the bakfiets next to me is Dave Cohen.
His passenger (sitting backwards) is reading the book "Life is a Wheel".
Photo courtesy of Dave Cohen.

About 2/3's way along the route.

Sometimes you don't want Dad's help, you just want to peddle yourself.
She actually rode the whole parade!

My word, the people!  It's heartening to think that most of them are in favor
of local food and agriculture, and so were probably very interested in biking too.

Our line up of bikes during the afternoon after the parade at the Bike Petting Zoo.  We answered all sorts of questions about our bikes.  I took a picture for a mountain biker from Virginia while he sat on the Bakfiets, and I had a great conversation with a couple from New Jersey about urban versus rural biking.

Yes, the LED flag staff lights up!