Friday, August 3, 2012

That GUY

I am obsessed with e-Bikes.

The year was 1976. I was 14 years old and put a used lead-acid car battery and 12VDC electric permanent magnet motor onto an old blue salvaged Schwinn bicycle. Thank you Bob Frisby, (owner of Frisby's Gulf station) for giving me that used lead-acid battery. You changed my life!

It was heavy: the battery alone was 50 lbs, more than the weight of the bike and motor together.

It was unstable: the only way the bike could stand up was with my weight on it, countering the weight of the battery.

It was slow: my mechanical Schwinn speedometer showed me reaching 18mph. Faster than a 14 year old could go on a heavy old steel Schwinn. Pretty good but not fast enough to avoid traffic any better than a bicycle.

It had short range: I could go a maximum of 6 miles with the car battery, unreliably. Meaning I could only reach out 3 miles and still get back home for a recharge.

It was fantastic: I loved it so much that I should have dedicated myself to the technology and pioneered better systems. But I had other, more pressing problems to solve. Instead I took a path that would raise my standard of living and allow me to provide for a family. 

The kids are grown and on their own. I achieved the family and career objectives. I never forgot the ebike euphoria. 

Now I have a chance to get it back.

Times have changed. Now we have Lithium Polymer batteries which have a power-to-weight ratio of over 10 times the old lead-acid batteries. We now have compact, powerful motor controllers using IRFB4110 FETS that didn't exist back then and hub motors that are so simple, efficient and refined that anyone can build an ebike simply by swapping out a rear or a front wheel and adding a "torque arm" to keep the high torque of the motor axle from damaging the bike frame. (It can "spin out in the dropouts", a dangerous event. The wheel literally tries to leave the bike frame from the motor power. :-) )

Converting a bike you already own is now something mere mortals can do for less than thousands of dollars - you can spend about $800 on the electric components and end up with with smooth, strong, consistent performance and incredible efficiency. Imagine cruising around for 10 miles or more at 20mph for pennies a mile and not needing licensing or insurance (in North Carolina, USA) It's a great short-distance transport in situations where a bicycle can work, but you don't want to arrive sweaty.

The Story So Far

For the last year, I have been experimenting with a converted "Short Wheelbase Recumbent" (SWB recumbent) . I converted it to an ebike by replacing the rear wheel with a hub motor wheel, adding a controller, a computer display and a Lithium Polymer battery (in the little plastic box on top of the rear rack). Where I got most of my components from is Tell Justin "James Sent You"! :-) 

From the rear left, showing the big pannier bag that can hold clothes, laptop and cellphone:

Better view of the pedal drivetrain from this angle. The front sproket is 52 tooth, good for pedaling up to 30mph!

I could not resist stopping and taking a photo of today's gas price at a gas station on the way home. 

No gas today, thank you!
There's a problem with this machine: it's very unstable - so much so that I consider it unsafe at speeds I can attain with the electric motor. So I'm moving the components over to a new conventional upright bike, today. (August 3, 2012)

Next Machine: Gen2 eBike

The first ebike was experimental: I already owned the bike, so I didn't have to buy one. I figured out where to buy a low-cost version of a 26" rear motor wheel, added a controller, a monitoring computer and a Lithium Polymer battery.

I used the initial test machine, the SWB recumbent, to learn how to size the battery and what kind of performance to expect. The recumbent allowed me to "just do it": get on the bike, get somewhere, learn something. But it's not safe enough to ride to work every day, it has two different size wheels (so you have to carry different size tubes) high speed maneuvering is not stable, and low speed maneuvering, forget it: the bike wants to fall over to it's side very badly. Recumbent fanboiz may disagree with me, but you'll never see a recumbent in the X-games BMX tubes, that's for sure!

eBike performance is dependent on the particular bike, rider weight and the "mission": the distance, speed and route you need to make sure you can travel. To figure out what an ebike can do for you, there's this "experimental time" where you have to figure out if it will even work: the amount of power you have available and the durability of the bicycle components must be able to handle the loads and speed demands you plan to place.

More importantly: building an ebike is an abomination: bicycles are designed and built for people less than 250lbs pedaling up to 15-16 miles per hour.

When you convert to an ebike, you add about 30lbs in motor, battery, controller, cables and electronics. And you push the bike to be ridden, routinely, well beyond it's design speed. I'm aiming for 25mph - some ebike builders aim for 40-50mph: which is into the realm of an electric moped or light motorcycle.

The new ebike must be the production model: a daily driver - something I can use to get to work with at least two days a week. I went out and bought a bike specifically for the purpose with the characteristics I needed:

- a stable, crank-forward upright bike design
- 26" wheels front and back
- V-brakes (although I can switch to a disk brake up front and probably will)
- large, strong frame with a large main triangle for battery installation, braze-ons for water bottles, rear rack/panniers
- A big, cushy, comfortable seat
- Something faster than mountain bike gearing. I'll probably swap out the front sprocket/shifter at some point also....

I don't want to build an electric moped or light motorcycle. This is to be a true hybrid bicycle with both the motor drivetrain and the human pedal drivetrain to be fully functional, viable means of propulsion. If the battery runs out of juice or some component fails (up to and including the motor) then I want to be able to get home under my own power. That emergency transport mode is important to me for everyday reliability. Plus, there is an exercise aspect to it that I want to preserve.

This bike is very big, you just can't tell it from the photo. The wheels are 26" diameter mountain bike wheels. The tires are so huge, they make the wheels look small: those tires are over 2 inches thick. For reference, conventional road bike wheels are "23c" - less than an inch thick. These fat 2" tires will eat even more energy but I'm going to try them out for safety's sake: they should much easily absorb road bumps and obstacles.

This bike will be much less comfortable and much less efficient than the SWB recumbent. I'll wear "office clothes" into work, but change into riding shorts on the way home for the hard workout.

I expect power consumption compared to the SWB recumbent to rise from 15 watt-hours/mile (SWB) to 20-25 watt-hours/mile (new bike). That's never a good thing for a battery powered vehicle as it shortens the available drive range. I'll be looking for ways to improve the efficiency.

If you've never ridden an ebike, stay tuned. I'll post pictures, data and describe how it works and what it's like. I have a "build thread" over at endless sphere forums. For more information, check out

The plan is to ride into work with very little, light pedaling. Enough to wake me up but not enough to get sweaty. Then after work to ride home hard as I can go, both from pedaling and the motor assist, getting a shower when I get home.

I am under no illusion, this idea will become much more of a challenge as we go from summer to fall to winter here in the eastern US. I don't want to give up just because the weather goes cold, dark and wet, but I'm not at all certain this is a vehicle I'll want to be riding on a dark, late fall day in rain just a few degrees above freezing.

Becoming "That GUY"

A good friend of mine now says I'm becoming That GUY...the fruity fellow you  see at some point during your commute: he's walking, biking (maybe riding a really strange bike or some weird motorcycle). He's always out there, come rain, shine or cold. Why would he do something stupid like riding a bike in bad weather during rush hour, rather than just give up and get a car, stay warm, smart and anonymous? Just who does that fool think he is? :-) :-) :-)

If I have to become That GUY to get my fat ass out of the car and quit spending money and wasting my life riding around on cushy seats insulated from the environment around me and burning petroleum, then OK. If getting out of the spam can with the rest of the lemmings makes me That GUY....then so be it.

I am obsessed with being energy efficient and what I burn in gasoline or electricity is of great interest to me. I drive a hybrid for that reason. But the hybrid, as good as it is, doesn't tell me everything. The ebike, with it's onboard computer measuring watt-hour usage, gives me even more data second-by-second. I'm excited to know exactly how much energy I spent getting to work on an ebike! (and BTW, it was about 548 watt-hours each way on the SWB recumbent, or about 1 kilowatt-hour round trip. For comparison, one gallon of gasoline can produce about 36 kilowatt-hours.

On the ebike, I'm 54 times more efficient than my hybrid Toyota Prius. If I burn 1.5 gallons getting to work and back (75 miles round trip, 50mpg, about 1.5 gallons), then it's the equivalent of getting 2700 miles per gallon! That's a pretty good reason to be That GUY, and I'm not alone: there are enough of us doing this that we call it "The Electric Revolution". We have suppliers, we have storefronts, we have parts being made and we have ongoing innovation.

But I don't want to be a cold, shivering That GUY. I'm interested in meeting the challenge comfortably, getting some exercise and seeing if that kind of a ride is usable even in terrible conditions.

My motives are stingy and selfish. I want to spend very little to get to work and stop putting miles on my expensive Prius. To do this successfully, I plan to stay comfortable and more importantly, ensure that the bike performs as it should!



  1. I'm looking forward to seeing the result! The granola peeps in Colorado would pretty much boo me right off the road, but a 13 mile ride to work with a total of 1000 feet of altitude to crest (5800 start, 6800 peak)... and myself being not being a endorsement encrusted uberbiker... I am intrigued by the electri-bike concept!

    Make sure your build pics and data are plentiful as promised!

    What was your top speed reached on the recumbant by the way? For future comparison's sake?

  2. Hey Steve: Top speed on the recumbent was 33mph (under power) at 72v, with 35mph possible downhill. At 96v, I could hit 41mph on good, level road. On that SWB recumbent, NEITHER one of those speeds did I consider safe, and dismantled the bicycle. However, I did not discard the bike - I put it back to what it was before and I fully intend to ride it again in the future. At normal bike speeds of 5-25mph, it's safe and comfortable.

  3. Side note about the new ebike: I've hit a snag regarding the "torque arm": this is the part that prevents the motor shaft from spinning in the dropouts and is a vital component. I've been trying to find an off-the-shelf part that will fit, and nothing fits this bicycle. I've come up with a solution, though, and should be able to implement it by this weekend (Sept. 22). YES, I will gladly post plentiful build pics and data :-) :-) :-)