|A Software Guy's Look at Electric Bicycles|
|By David Adams on 2012-08-01 16:53:08|
|I had the chance to attend the bike industry’s annual DealerCamp in my hometown of Park City, Utah last week. It’s an event where dealers and manufacturers can meet up, and everyone can try the latest bicycle technology on the roads and trails. While there, I took a particular interest in electric bicycles, which were represented by several vendors. Electric bicycle tech has made some major strides in the past few years, but still has a long way to go, in particular on the software side.
Pretty much since their inception, electric bicycles have been characterized by sketchy-looking self-conversion kits and uninspired if not downright bizarre-looking bicycles. All of them, of course, aimed at smooth pavement riding and commuters. So when I walked by the BionX booth and saw and electric conversion of one of the craziest and coolest looking bikes available, I was immediately interested. I’m a die-hard mountain biker, and don’t have much use for road bikes of any stripe, so I’m a bit biased, but I think anyone’s head would be turned by what I saw.
It was the incomparable Surly Pugsley, a mountain bike with huge, oversized rims and tires, ostensibly designed for riding on snow, sand, and other soft terrain, but really designed just to be awesome looking. Its rear hub was built up with the PL 350HT SL XL brushless electric motor, and it had a big battery pack attached to the frame. On the handlebar was a console that looked like a conventional bike computer/speedometer, only larger.
I took this bike for a spin up a pretty serious mountain biking trail near Deer Valley, and I had a smile plastered on my face the whole time. It was about the most fun I’ve ever had on two wheels, and I have ridden some of the most amazing and famous mountain biking trails in the world.
This latest-generation electric hub motor isn’t designed to be able to propel a bike uphill on its own. You can think of it like a hybrid car, only instead of supplemented by a gas engine, it’s supplemented by the rider’s pedaling. While riding uphill, I pedaled steadily, and the motor supplemented my efforts. The amount of “help” was configurable by hitting the + or - buttons on the console, or on a thumb control keypad next to my right grip. I kept it set to “four bars” the whole time, which was the maximum amount of boost.
It also features regenerative braking, so while I was watching the battery indicator diminish as I was going up, I got it to recharge a bit on the way down. Unfortunately, most of my downhill was steep enough that I was also riding the brakes. I kept thinking, “what a waste of good potential energy!”
It was a hot summer day, and I was dressed for the office, which in my case was jeans, an under-shirt, and a short-sleeved button-down shirt. I rode steadily uphill into the mountains until the tents and vehicles in the parking lot below looked like toys. Normally, after fifteen minutes of riding like that, I’d be drenched in sweat, dressed as I was. But in this case, my pedaling was light enough that I felt as fresh as I would if I’d been strolling slowly along those shady mountainside trails. If I’d rolled up to my office, I would have been able to sit right down, with no shower necessary.
The Surly Pugsley is not the most efficient of mountain bikes. It’s a novelty act. Its big wheels take a lot of effort to keep rolling, but its big tires and low air pressure make for a comfortable roll, and I was tearing up and down the switchbacks. The electric boost made what would have been a slog into a joy. I also ride motorcycles sometimes, but this ride was completely unlike riding a motorcycle. Despite the 14 pounds of extra weight for the motor and battery, the bike felt lighter and more maneuverable than any motorbike, and it didn’t propel me along. It felt like bicycling, only easier. And of course it was completely silent.
As fun as it was to ride on the trail, it was just as fun to ride around the roads. I was able to easily ride up a flight of 12 stairs. I kept thinking that even being an off road bike, the motorized Pugsley would be a blast to ride around town every day.
But while I was riding along, I was also cataloging the bike’s shortcomings. There are the obvious ones: the motor, and especially the battery, are much bulkier and heavier than I wish they would be. Adding 14 pounds to an already-heavy 35 pound bike makes it downright bulky. Having the option of putting out more torque for a bigger boost would be nice, though it would obviously eat up battery power. And as I mentioned, the regenerative braking wasn’t up to the downhill speeds I was reaching.
And of course, what dashed my dreams of buying the motorized Pugsley was the price. The motor and battery kit is about $2100. Possibly justifiable if I were to buy it for an everyday commute, but impractical for a recreational trifle.
But I think some of the most interesting improvements to this bike, and all electric bikes, could be made in software. I’m hopeful that in the next decade, along with advances in battery technology that every smartphone owner has already been pining for, we could see electric bikes get a lot smarter, and therefore more practical, and more popular.
The BionX system isn’t just a dumb motor with an on/off switch. As they describe it, “Energy is provided in proportion to the torque applied to the pedals: Pedal harder and get a stronger and faster assistance, pedal lightly and receive gentle, gradual assistance. Stop pedaling and your assistance is automatically cut off. Each pedal stroke is analyzed separately by a microprocessor, equalizing your energy so you can concentrate on enjoying a smooth, powerful and precise ride.” I could feel that the boost was adjusting as I modulated my pedaling effort.
The BionX system’s regenerative braking was something that I was very excited about. Because of the mountainous area I live in, I often have long, steady descents, and it would be great to be able to generate electricity. Unfortunately, you’re not going to be able to ride bike up the hill, and have the ride down power you back up. For various reasons, the regeneration doesn’t recover a substantial amount of your energy. On topsy-turvy sections, I wasn’t able to reap the full benefit of either mode (boost or regeneration) because you have to be moving at a certain speed before the boost kicks in, and you have to actively engage the regeneration, either by hitting the rear brake gently or by setting it on the console. There were times when I was burning battery and spinning the hub when I didn’t need to, and likewise times where I was heading downhill and not recovering electricity, or recovering less than I could have.
The BionX system does monitor some data and adjust accordingly, but I think there’s room for improvement. For forward momentum it would take very little computing power and a few sensors to be able to calculate the various inputs (speed, incline, pedaling speed and torque, alteration in pedaling cadence, the accelerometer graph) and calculate an optimal amount of boost for each condition, second-by-second. Individual settings could be fine-tuned, with a rider’s preferred speed at various levels of incline and relative pedaling effort. The system could even be set to learn those preferences in a special mode. Managing the motor’s function more carefully could save energy. Also, with the conditions being monitored by software, the regenerative braking could be applied much more liberally, recharging the batteries more.
With a powerful-enough motor and smarter systems, it might be possible to simplify the bike’s mechanical systems to make the bike lighter, more foolproof and easier to maintain. The bike I was riding had a conventional mountain bike drivetrain with a 27 speed derailleur setup. That’s necessary to provide a low enough gear for climbing, but a high gear for riding fast on flat ground. A powerful motor might be able to make it practical to use a simple single-speed drivetrain, and possibly even eliminate the rear disk brake entirely, by supplementing the rider’s pedaling with motor power efficiently, and using only the motor to slow the rear wheel while braking.
While I was riding, I was also wondering whether it would be feasible to do a completely drive by wire system wherein the pedaling only charges the battery, and isn’t connected physically to the wheel at all, similar to the way that some heavy equipment uses a large diesel powerplant to generate electricity to electric motors, and does away with a mechanical drivetrain altogether. Would that result in unacceptable inefficiency? Maybe that would require a motor that’s more large and powerful than would be practical.
Throw in some other mobile computing capabilities, and things can get really interesting. A GPS receiver and Wi-Fi (to pull down data while you’re at home) could enable the onboard systems to recognize a trail or road that you or some other user has ridden before, and implement a power profile that anticipates every hill with perfect precision, not only applying motor power and braking efficiently, but being able to indicate exactly what point on the trail ahead it will run out of battery power. And of course, it would be nice to have a usb charging slot on your bike when your phone loses power, not to mention some built-in LED lighting for the night time.
Many serious cyclists are sure to scoff at the thought of motorized cycling in any context other than commuting and tooling around town. I’m sure that if the people I passed on the trail had known I was on a motorized bike some would have looked askance. There’s a feeling that if you’re going to be on the trail, you need to deserve to be there, by working for it. And of course one of the most popular reasons for recreational cycling is exercise. But the truth is that serious cyclists spend thousands of dollars on their bikes to trim a few grams here and there, all so they can get up the hill and not have to work as hard. Is that cheating? Does the guy with the $4000 bike deserve to be there any less than the guy on the $200 beater because he’s got it easier? As long as motorized bike users aren’t going any faster and aren’t making any other noise than other cyclists on the trail, then it shouldn’t make a difference.
The truth is, most people who shun cycling do it for one simple reason: it takes too much effort. If you remove some of the effort, you get more people on bikes. And while riding an electric bike creates more pollution than riding a regular bike, it’s a hell of a lot less than driving a car, or even taking a bus. I’d suspect that riding an electric bike for an hour takes less electricity than watching a plasma TV for an hour.
The more people you get on electric bikes, the prices for the equipment does down. The $2100 kit I rode probably has similar technology to the high-powered cordless circular saw I own. But the saw costs about $400, because it’s produced in high volumes by a large international conglomerate in a brisk competitive marketplace. The bike kit is manufactured in small volumes by a specialty outfit. I for one am really looking forward to a future where electric bicycles are smarter, lighter, and cheaper, and therefore much more popular.