Posts Tagged: perfection


14
May 2010
by don

The perfect bike

After months of grey skies, the sun has finally returned to Seattle.  If biking in damp weather is fun, biking on a clear spring day is nothing short of euphoric. Our area is blessed with snow-capped mountains, lakes, abundant greenery, and flowers.    It is so much easier to appreciate this on a bike, I am again pondering what it would take to get more of my neighbors on bicycles.

As I see it, there are three parts to the equation:  better hardware, better infrastructure, and a shift of expectations that allows people to consider alternatives to the car.  Given some months of experience with this bike, I’m ready to start imagining what improvements to bike hardware could expand the biking experience to more people.

Average the effort

To my mind, there should be a nice middle ground between a manual bike, where all of the energy comes from your muscles, and a moped, where none of the energy does.  It would be cool to pedal at a constant, comfortable rate no matter what the terrain.  When you’re going uphill, you would be taking energy out of the battery, and when you’re going downhill (or flat at less than maximum speed), you would be putting energy in.

On my bike, I still crank the pedals pretty hard going up the hill, even though it’s nothing compared to when I turn the electric motor off.  Then I coast down the hill, recovering a little energy due to regenerative braking, but I could do more if I were actually pedaling.  I don’t pedal because the hill is too steep: I would start going uncomfortably fast.

More power

I can ride up our hill at about 10 miles per hour unloaded, or about 5 miles per hour with a passenger.  However, I wouldn’t mind going a little faster and putting in somewhat less effort.  Perhaps the BionX motor isn’t the ideal choice for this hill, but I love its quiet operation.  It emits a very low hum under the largest loads, but it’s not a sound most passersby would notice.

Reduce maintenance

Although our cars need occasional maintenance, it’s amazing how reliable they are.  The weak part of my bike seems to be the gears: I’m still missing a few that I could probably recover by doing some adjustments to the derailleur.  It’s kind of a pain to do it myself, and I don’t want to take it to a bike shop, so I just live with it.  But I really wish I didn’t have to deal with gears at all — I want an automatic transmission like my car.  I want to pedal at that nice comfortable rate and have my bike figure out how to apply that energy to the task of moving me and my stuff forward.

The perfect hill-climbing bike

The perfect bike for our hills would feed energy from my pedals into a continuously-variable transmission, combine it with energy from the electric motor, and scoot me forward at 20 miles per hour regardless of the pitch of the hill.  However, that transmission sounds complicated and expensive, and possibly not reliable.  Instead, maybe I should have a powerful motor driving the bike by itself, and my legs just turn a generator that adds charge to the battery.  I know that won’t be ideally efficient: converting mechanical energy to electricity and then back to mechanical energy will come with a significant tax.  More electricity will be needed from the plug to compensate.  However, I’m already accustomed to recharging my battery in order to go anywhere, so I don’t think this is a showstopper.  Then my friends can put in whatever effort they want.  If it’s a hot day and they don’t want to sweat, they could ride the bike like a moped without putting in any effort at all.  Such a bike would work for people of all fitness levels.

But I like the idea of pedaling not only to contribute some of my own energy to the task (thus improving fitness), but it’s also a nice control system.  Pedal faster to accelerate, slow down to go slower.  That seems more natural than twisting a handle bar grip like a motorcycle.

Keep dreaming…

I would like to experiment with the bike I’ve described, but the first challenge is finding a pedal-powered generator suitable for mounting on a bike frame.  It’s hard to find a manufacturer with a product like this, because generating power with leg muscles is a pretty discouraging experience.  First you need a heavy flywheel to smooth out the effort.  Even then, most people who try it find that it takes a huge effort to generate a few cents worth of electricity.  This mirrors my experience.  The three cents that I spend to fill up my bike’s battery delivers a huge amount of power to my bike’s wheel compared to what I can do with my legs.  

If any of my readers knows of a leg-powered generator that might work (smooth operation but not too heavy), let me know:  don “at” mycargobike.net

What do you think?  Is there something I’ve overlooked, or do you have different ideas about how a powered bike should work?  I would love to hear them!