Here’s a little photo essay about my family’s bicycles. I’m proud to say that we use our bikes a lot. Each bike is tailored to its user: I drive a cargo bike capable of carrying passengers and cargo long distances; my wife drives a slower and lighter but more stylish bike; my 11-year-old daughter Thea and her friend JJ drive bikes tailored to their 2-mile drive to school. (My son Jasper, aged 15, resists having a bike. He pretty much walks wherever he needs to go.) Ithaca is hilly, so it’s important for a utility bike to have an electric motor. I’ve spent a lot of time over the last couple of years experimenting with electric bike motors and other accessories. Maybe you can benefit from my discoveries.
From left to right my bike, my wife’s bike, Thea’s bike, and JJ’s bike in front of our bike stable.
My bike is a Surly Big Dummy Xtracycle with Stokemonkey motor, described in detail elsewhere. I named it “The Spirit of Ithaca”. I’ve changed so many parts it’s hard to give it a value, but you could probably get a comparable electric cargo bike for $3,000. Bicyclists may notice that my bike has an unusually large chainring. Last year I doubled the voltage of the motor from 36 to 72v, making my bike much more powerful—it can carry two adults up the steepest hills in Ithaca. Since by design the Stokemonkey motor moves the pedals, the increased power increased the speed of the pedals and it became necessary to increase the size of the chainrings to slow down the pedals.
My bike is powered by two 36v10ah LiFePo4 batteries in series. They give my bike an enormous range of about 70 miles at 12mph or 35 miles at 20mph. However, each battery weighs 15 pounds and they are expensive at $600 each.
My bike sports a DIY headlight I made out of about $50 in parts available at SparkFun.com. The headlight is powered by Grin Technology’s 12v voltage regulator which can take any ebike battery input from 24 to 72v and output the 12v required by the headlight. I’ve also used the 12v output to recharge my phone on long trips. The advantage of this centralized electrical system over a “regular” bike’s discrete lights is that I just have one switch to turn on all my lights and accessories, and I only have one battery and that battery is rechargeable.
My DIY headlight has a homemade look that you just can’t buy at stores :-). I keep it on both night and day. It’s bright enough that I keep it pointed down and I run it at half power to avoid annoying people.
Turns out my DIY headlight’s big heat sink is not necessary with the lower-power LED driver I’m using. I’m planning an updated version that uses the handlebars as a heat sink.
My wife’s bike is a Sanyo Eneloop we purchased used for $1,500. She named it “Zippy”. The previous owner purchased it for over $2,000 from NYCE Wheels. (At 350 miles away, NYCE Wheels is the closest ebike store that I know of.) Zippy is a highly reliable bike compared to my bikes, which are constantly breaking down and in flux as I experiment with them. Besides the reliability, the most important feature for her is the chain guard which is necessary because she bikes to work in her nice work clothes.
She has a rear rack but rarely uses it in favor of the faux-wicker front basket. The hub motor is in the front wheel and the rear human-powered hub has three speeds.
Sanyo is a battery manufacturer and built the bike around their NiMH battery. The bike is surprisingly powerful and has a range of five to 10 miles. It’s not fast but it is so stately that you don’t feel like going fast when you are riding it.
In practice bicycling can be a hassle because of all the little business you have to do when you get on and off your bike: put on your reflective bike jacket, put on your helmet, tuck in your pants cuffs, turn on the lights, unlock the bike, put up the kickstand, etc. That’s a lot to remember and it creates an unconscious impediment to biking, especially when you know that driving a car just requires opening the door, turning the key, and going. I got my wife this nice AXA wheel lock from Clever Cycles to reduce some of the hassle. Basically you press a lever and take out the key to lock the bike, and insert the key to go. No more fumbling with a cable or u-lock.
Thea (left) and our neighbor JJ (right) used to walk a few blocks to elementary school but this fall they started at a middle school about 2 miles away. They were discouraged to find that the school bus takes 45 hot and stuffy minutes to get to school. The city bus only takes 15 minutes but costs $.75 and requires a 10-minute walk downtown. Biking, on the other hand, only takes 10 minutes! Thea already had an electric bike, and we equipped JJ’s bike with a motor too so she could keep up. I escorted them for the first few months and helped them work out a safe route.
Thea has a nice lightweight mountain bike equipped for utility with a rack, kickstand, fenders, lights, and a front hub motor. It’s a kids bike with 24″ wheels, but I often ride it myself—it’s kinda sporty! The motor is powerful enough that I don’t need to pedal. In retrospect I should have installed a rear hub motor instead of a front hub motor. The front wheel spins out on hills. In general I’ve concluded that front hub motors are not suitable for Ithaca.
I added Marathon Winter studded snows tires to Thea’s bike so that we can ride together safely this winter. I unequivocally insist than anyone who rides in the winter should use these tires.
Thea’s motor is a Nine Continents direct drive hub kit from E-BikeKit.com for about $500. There are a lot of ebike kits out there but E-BikeKit is especially dedicated to excellent service. You’ll notice that I had to file off the “lawyer lips” around the dropouts in order to get the hub motor axle nuts to seat properly. Grin Cyclery’s excellent troubleshooting page tell s how omitting this step may lead to front fork failure.
Originally I built a 15-pound lead-acid battery (described in a previous post) for Thea’s bike. This fall I began experimenting with lithium polymer (“lipo”) batteries, the same type of battery used by Radio Control enthusiasts. Not only are lipo batteries lightweight and inexpensive compared to my LiFePo4 and lead-acid batteries, they have a much higher discharge rate. This makes it possible to have a very small battery that can output enough amps to propel an ebike. So on Thea’s bike I replaced the three heavy 12v 10ah lead-acid batteries in series (a 36v battery) with two lightweight 18.5v 3ah lipos in series (for a 37v battery). Here’s the score: the lead-acid battery is 15 pounds, $100, 360wh, with a 36 mile range. The lipo battery is 2 pounds, $50, 108wh, with a 10 mile range. Which is better? It depends. My bike needs more range and weight is not a problem, so lipos are not a good option for me. But for Thea’s bike the lipo’s low weight is very appealing and their short range is not a problem.
Thea’s controller and battery fit nicely in her trunk with room to spare for lunch.
Thea and JJ’s bikes both use two 18.5v lipo batteries connected in series for a 37v battery pack. The RC charger, however, needs to charge them in parallel at 18.5v. I made special connectors to switch the batteries between serial and parallel, similar to the lead-acid battery connectors described in a previous post. In this photo the parallel connector is on the top connected to the battery and the serial is on the bottom in my hand. In addition to the power output connectors, lipo batteries have “balance” connectors to enable the charger to manage each cell individually. This photo shows a parallel balance connector I made so that I can charge a 37v battery from one charging port.
Lipo batteries can be dangerous. I came across a post on one RC forum listing everyone on the forum who had had a house fire of some kind caused by lipo batteries. There were dozens of people on the list. That said, I haven’t had any problems with them myself. I try to be careful. I always balance charge my lipos. I make sure not to drain them below their limit. I charge them in a fire-proof bag as shown. That’s the charger on the left, capable of charging four batteries at a time.
On a couple of occasions I’ve had the pleasure of driving JJ’s bike a few miles even though the seat barely comes up to my kneecaps. As with Thea’s bike, it’s a perfectly plausible form of transportation for an adult since I don’t have to actually pedal. The small wheels and the hub’s internal gearing give it incredible torque. And the small frame makes it fine for riding unobtrusively on the sidewalk, nobody minds. I once rode it a mile up State St. in Ithaca and it was sort of like going up the hill in an electric wheelchair.
JJ’s battery and controller fit into a tiny seat pack. Can you believe it?
I bought this high-end mountain bike (code-named “Black Beauty”) used for $400 with the intention of building it up as a replacement for my Big Dummy. So far I’ve added a hub motor and perhaps I’ll add an Xtracycle longtail extension in the spring.
Black Beauty has very nice components, including hydraulic disc brakes and fully adjustable shock absorbers. I wasn’t looking for these but both of these features turned about to be important as described next.
A couple of weeks ago I bought a $600 Crystalyte HS 3540 conversion kit from Grin Tech. I paired this state-of-the-art hub motor with a controller capable of handling almost 3kw (72 volts at 40 amps). (For comparison my Big Dummy typically runs at 1kw.) After a few technical difficulties I was able to put Black Beauty to the test. I found a quiet level stretch of road, pulled back the throttle, and let her unwind. She accelerated quickly to 40mph. At first it was frightening. Then it was exhilarating. But in the final analysis it’s embarrassing how fast this bike can go, since elsewhere I’ve blogged about the evils of speed. My main interest in building a high-powered bike is to make it capable of carrying adult passengers. Being able to go fast is an annoying side effect.
Black Beauty sports a Cycle Analyst and an LED headlight, both from Grin Tech.
For now I have Black Beauty’s battery and controller stuffed in a pannier. As you can see I’ve also outfitted Black Beauty for carrying vegetables.
Another secret to Black Beauty’s performance is the 72v battery pack I put together out of four 18.5v 5ah lipo batteries. This battery pack cost me about $200, weighs about six pounds and has 360wh of power. That’s enough power to go about 10 miles at 25mph. I could probably go farther at a lower speed but it’s hard to go slower than that.
The Clarkbergs have two nice his and hers road bikes in the basement. One reason they are in the basement is that they are so light it’s easy to carry them up and down the basement stairs. Another reason they are in the basement is that they are recreation-only vehicles that my wife and I rarely use. I think we only took them out once last summer. I drive my cargo bike so often for utilitarian purposes that the thought of riding my road bike for recreation doesn’t appeal to me. I mean, how often do you drive around your car for recreation?
A couple of years ago I commandeered our garage for housing our bikes. I added a nice sliding door for easy access.
Our car. As a family we’re not so fanatical about bicycling that we’re willing to give up a car altogether. When we recently bought this new car I think some of my friends were surprised we got a Mini instead of a Prius, the environmentalists’ vehicle of choice. As I’ll describe in an upcoming post, I think it’s much more important to our communities and to the environment that a car be small and slow rather than use less gasoline. Large fast cars contribute to a transportation infrastructure that is inhospitable to the rest of us not driving a car. My friends take some pride in their mpg, but their lower mpg doesn’t make me feel any safer biking. Also mpg-pride seems misplaced if someone is using their large four-seat hybrid car for personal transportation. I’m not against technology, but I believe in appropriate use of technology. I only use our car by myself when I have something heavy to carry or when I have to go beyond the range of my bike. Otherwise I drive my bike.
The Aqua-Xtracycle is a do-it-yourself amphibious electric cargo bike. This video shows how it works, and the photo gallery below shows a bit of our development process. In a future post I’ll describe how you can make your own Aqua-Xtracycle.
This pontoon boat cost about $250.
The first prototype used a wooden dowel to support the pontoons.
Rear view of the first prototype.
Thea on the first prototype.
When I got on the first prototype the wooden dowels broke.
The bike got wet.
Testing tent poles.
Second prototype with 6061 aluminum poles.
Second prototype at our Stewart Park testing grounds.
For now just using paddles for propulsion.
Learning to weld and braze.
Clockwise from top: Xtracycle, pontoon frames, trolling motor and battery, front float, and pump.
Failed attempt to attach paddles to the rear wheel.
Seaweed was a problem.
A platform helps shape the front wheel float and keeps the front riding higher.
A Halkey-Roberts valve inflates and deflates more quickly than an inner tube valve.
Four BMX handlebar stems fit into the Xtracycle horizontal-rack tubes.
Two diagonal supports snap on from the pontoon frames to the Xtracycle vertical racks.
A cotter pin secures a $100 electric trolling motor to the rear of the bike frame.
Caution: shop talk blog post intended for do-it-yourselfers. For my recent 240-mile journey I created what I call my “trip batteries”—batteries that I can attach to my bike to augment my regular batteries, but that I don’t intend to carry around on a daily basis. As such, the main design criteria for these batteries is that they be inexpensive. I don’t want to pay the big bucks for a battery that I only use once in a while. The obvious choice is SLA (sealed lead acid) batteries. These are the same kind of batteries used in cars, and the technology is almost 100 years old. E-bikers out there may poo-poo this choice of battery. After all, compared to my lithium batteries, my SLA batteries are heavy (20lbs vs. the lithium’s 15lbs), not quite as powerful (600wh vs. the lithium’s 720wh), don’t last as long (300 charge cycles vs. the lithium’s 1,500) and they are dumb (that is, they don’t have a battery management circuit board in them to prevent human error from damaging them, although most controllers provide the necessary protections). But they are cheap. I can put together a 10ah 36v battery for about $120 versus a 10ah 36v battery for $600.
Furthermore, there are many reasons to have some SLA batteries around. One is that their native voltage is 12v. I’ve created custom connectors for my batteries so that they operate at 36v when they are on my bike, but I charge them at 12v (see the images below). I find that 12v chargers are much more reliable than chargers made to output other voltages. I’ve had several 36v and 48v chargers self-destruct.
I can also power 12v appliances. 12 is a magic number in the appliance world. The boating, camping, and RV industries produce all kinds of 12v appliances. I have some small solar panels and those too output 12v. And I purchased an 800w inverter ($80) to power 110v household appliances. I recently used it to power my electric weed-wacker when I was at too great a distance for a power cord to reach the weeds. I do have a 12v converter for my lithium batteries, but it can only output about 240w.
How did I make the batteries? My bike operates at 72v, so I made two 36v 10ah batteries that I connect in series when they are on my bike, one battery on each side. Each 36v battery is made up of three 12v SLA batteries in series. As I mentioned, I can quickly convert the 36v 10ah battery to a 12v 30ah battery by switching from a series connector to a parallel connector. I used scooter batteries since I figure they are designed for a similar application. I connect the batteries with 10awg wire. Thick wire is essential since these puppies will be outputting plenty of juice. The wire has spade connectors on the battery side and Anderson connectors on the output side—Anderson connectors are an awesome tool for the hobbyist. They are the Lego of the connector world. I should probably put a fuse in my battery pack. I then wrap up my pack with a layer of duct tape.
I considered making a special battery box but I decided that the batteries are waterproof enough, and they are so ugly they are probably theft-proof too. So I simply strap the batteries to the “footsies” on my Xtracycle bike. Footsies are wooden platforms that my daughter rests her feet on when she is riding with me. This spring I did a test drive out to Sheldrake Point on Lake Cayuga, some 25 miles from my house. The trip batteries performed admirably and took me almost the full 25 miles at 20mph, drawing 600wh in the process. (Note that I probably could have gone 50 miles at 12mph.) Then I switched to my lithium batteries for the ride home. Yes to switch batteries I have to actually stop, get off my bike, physically disconnect the spent batteries and connect the fresh ones. Someday maybe I’ll connect my SLA and lithium batteries in parallel, but I understand it’s important to put some electronics between batteries using different chemistries.
Let me know how it goes making your own SLA battery packs!
Also visible: Stokemonkey electric motor.
Trip battery and footsie shelf.
Charging up with the parallelizing connector.
Three 12v batteries to 12v parallelizing connector.
Three 12v batteries to 36v output serializing connector.
“Can the solar panel drive the electric motor directly?”
“Did you make it yourself?”
“What the…”
Allow me to explain. My vehicle of choice is a “stoked Xtracycle”. (For those of you not “in the know”, an Xtracycle is a type of cargo bike that has an extra long frame. And “stoked” means that my bike has a Stokemonkey electric motor that helps me out on the hills.) In general this summer I’ve been biking 10 to 20 miles a day and then recharging my battery overnight by simply plugging it into an outlet. However, next week I’m going on a 3-day 240-mile camping trip through the Adirondacks where I might not have access to an outlet. The solar panels will help extend the range of my bicycle. So to answer your questions:
“Why do you have solar panels on your bicycle?”
I use them to extend the range of my electric cargo bike for long trips (plus they were fun to make). I will carry two batteries on my trip, each giving my bike a range of 20 to 40 miles. On a sunny day the solar panels can recharge one of the batteries while I am riding, adding an additional 20 to 40 miles for a total range of 60 to 120 miles a day. I anticipate some hills and I’ll be carrying a load, so a 60-mile range is probably more accurate. I may need to pedal the last few miles on some days.
“What do you do when it’s cloudy or it rains?”
I plan to stay in a hotel some of the time and recharge my batteries there.
“Can the solar panel drive the electric motor directly?”
Not really. The solar panels don’t produce enough electricity instantaneously. For example the solar panels only produce about 40 watts of power at a given moment, whereas my bicycle needs about 400 watts of power to go up a hill. The main purpose of the solar panels is to charge the battery over time. Since charging happens slowly, 40 watts is enough to charge the battery. It takes roughly 10 hours of charging to store one to two hours’ worth of electrified riding time in the battery. And one to two hours of riding translates into 15 to 30 miles.
“Did you make it yourself?”
I already had the stoked Xtracycle, which is described on my About This Bike page. As you can read there, an electric cargo bike can be had for $1000 to $3500. And I had already constructed the canopy frame for a previous project, the Bike Wagon Canopy ($150). I found the canopy was somewhat wobbly with the weight of the solar panels so I had to strengthen it with guy wires. It remained for me to add the solar panels and the electronics. I used maritime-grade solar panels that were designed to keep sailboat starter batteries charged up, so they are extra-sturdy and consequently somewhat expensive. I’ve since seen panels with almost twice the power at 3/4 the price. Cost of panels: $900 to $1200. I am using three 12-volt panels in series to produce the 36 volts required by my battery. I spent a lot of time researching what sorts of electronics I would need between the panels and the battery, and finally concluded that I can just plug the panels into the battery directly. (I plan to write more about this in a later post.)
Total cost for a solar bicycle: $2050 to $4850. Not bad for a vehicle that can get you both out of the car and off the grid.
In a previous post I described a canopy that Thea and I made for our Xtracycle to protect her from wind and rain. It looks sort of like a covered wagon on the back of our bike. It was easy to build without special tools or parts, did not require modifying our bike and cost us less than $150 for parts. It weighs about 2 lbs. and we can set it up in less than five minutes. Here’s how to make it.
Materials You Will Need
(1) Xtracycle
(1) 7/8″ x 48″ dowel
(4) 3/4″ long wood screws for the base
(4) #6 x 3/4″ machine screws and nuts
(12) 18″ x .340″ aluminum tent poles with inserts
(2) 18″ x .340″ aluminum tent poles without inserts
(4) 18″ x .626″ aluminum tent poles with inserts
(1) 18 x .625 aluminum tent pole without insert
(4) .340″ 145 degree tent pole elbows (ignore the holes)
3 yards by 60″ of silicon-coated rip-stop nylon cloth
25 feet of light cord
(4) grommets
(4) buckles and 25 ft. of 1/2″ webbing
Tools You Will Need
hand saw
drill (although use a drill press if you have one)
#1024 1.1 OZ SILNYLON 1STS , (Tan)…3 at $9.99 = $29.97
#4060 TENT POLE W/ INS .625 18 inch Black…4 at $4.95 = $19.80
#4061 TENT POLE W/O INS .625 18 inch Black…1 at $3.95 = $3.95
#4018 TENT POLE W/INS. .340 18 inch Black…12 at $2.60 = $31.20
#4019 TENT POLE W/O INS .340 18 inch Black…2 at $2.20 = $4.40
#4055 TENT POLE ARCH-145 DEGREE .340 BLACK…4 at $2.95 = $11.80
#2000 WEBBING- NYLON MED WT 1/2 inch Black..25 at $0.49 = $12.25
#3026 SIDE RELEASE BUCKLES – 1/2 inch…4 at $0.39 = $1.56
#4200 tubing cutter…$7.95
#3235 grommet tool (5/16″)…$10.99
#3231 (10) 5/16 grommets…10 at $0.18 = $1.80
purchase at a hardware store:
(1) 7/8″ x 48″ dowel…$3
(4) 3/4″ long wood screws…$1
(4) #6 x 3/4″ machine screws and nuts…$1
25 feet of light tie-down cord such as cotton clothes line…$5
TOTAL: $145.67
How to Make the Canopy Cover
The rectangular canopy cover fits over the canopy frame and is secured at the bottom with tie-down straps. The front and back of the cover can be cinched up with a drawstring like a covered wagon. If you like, the cover’s size can be adjusted, along with the frame’s pole lengths, for different sizes of passenger. The size I give here is appropriate for a large child or small adult.
1. Cut the cloth so that it is 108″ (3 yards) by 60″. The 60″ edges will be along the sides of the canopy, and the 108″ edges will be the front and back. Hem the 60″ side edges first, then the 108″ front and back edges. Make the hems about 1.5″.
2. Next make the drawstrings. Using a stiff wire as a big sewing needle, insert about 12 feet of cord into the front hem, then repeat for the back hem.
3. Next use the grommet tool to insert two grommets on each 108″ side, about 18″ from the front and back (the video below shows how to use a grommet tool). If you are using thin cloth, reinforce it first with an iron-on patch.
4. Cut four 20″ lengths of webbing for the tie-down straps. For each strap, sew one end of the webbing to the female buckle and thread the other end of the webbing into the male buckle. Thread the straps into each grommet hole.
How to Make the Canopy Frame
The canopy frame “base” consists of two 7/8″ x 24″ wooden dowels that are inserted into the Xtracycle h-rack (horizontal) tubes and secured with wood screws. Aluminum tent poles are then erected upon this base: a front hoop, a rear hoop, and two cross pieces.
1. Cut the 7/8″ x 48″ dowel in half so that you have two 24″ pieces.
2. Drill a 19/64″ hole 1/2″ from each end of each piece. Make the holes as vertical as possible and make them exactly parallel.
3. Insert a base pole into the Xtracycle h-rack, center it, and align the holes so that they are vertical. While holding the base pole in place, drill starter holes for the woodscrews where the h-rack tube has holes in its side.
4. Screw the base poles to the bike with the woodscrews. I just leave the base poles on my bike all the time. The front pole provides a nice footrest for passengers.
5. Next make the hoop poles. All you have to do for this step is cut four of the 18″ poles to 12″ (or a different length depending on your expected passenger size). The video below shows how to use a pipe cutter.
6. Next make the cross pieces from the .625″ poles. For each of the poles that have inserts drill a 11/32″ hole in the ends opposite the inserts, about 1/2″ from the end.
7. For each of the four cross piece ends insert an elbow piece. It may take some effort to get it in and you may have to hit it with a hammer.
8. Drill a 9/64″ hole that goes through the elbow that is in the crosspiece. Screw the elbows into place with the four machine screws.
9. Cut two 6″ pieces from the .625″ tent pole that *doesn’t* have an insert. These will serve as the center parts of the cross pieces.
How to Assemble the Canopy
CAUTION: do not leave your canopy frame uncovered. Without the cover it is only held together by friction. If jostled it could come loose and snap back with surprising force (and for example break a garage window as I learned from experience). DO NOT ride your bike with an uncovered frame (again as I learned from experience you don’t want to be picking up all 20 tent poles in traffic). If you want to use the frame for some purpose other than the Bike Wagon canopy, consider putting a shock cord within it or using external guy wires as I do for using it to support my solar panels.
Final step: do me the courtesy of sending me a photo of your finished canopy!
How to Cut an Aluminum Tent Pole with a Pipe Cutter
How to Add a Grommet to the Canopy Cover
How to Make a Canopy Sack
If you have enough cloth left over you can use it to make a canopy sack.
1. Cut the cloth to 27″ x 20″. Hem the 20″ side.
2. Fold the cloth in half and sew the edge, leaving an opening for the drawstring at the ends of the hem.
