HUMAN ELECTRIC HY-BRID

May 28, 2007 – Memorial Day

I took my electric motorcycle out for a ride this morning. As I rode past a fisherman on the banks of the Grand River he turned and said, “That is the quietest motorcycle I have ever heard”. While I enjoyed the quiet and peacefulness of the electric ride, I was thinking about building a human electric hybrid.…

Could I get the speed of my motorcycle coupled with the good qualities of my bicycle?

So, I decided that it was time to part out the motorcycle and build my Human Electric Hybrid: A bicycle with a supplemental electric drive system. The ideal invention would allow for fast, sweat-free commute times when required, unlimited range (if the battery dies, I can pedal to the next town), exercise, and quiet.

My Burley cargo trailer and my sons BMX bike.

“Hmm, maybe I can mount my electric motor in this baby?”

“Is getting pushed by an overloaded, flimsy cargo trailer 45 miles per hour really a very good idea?”

“Not really, but if it works it will be AWESOME!”

And think about the possibilities,

Ø Coasting to work.

Ø No sweat.

Ø Easy swap from one bike to the next.

Ø Ability to pick up groceries on the way home.

Imagine my surprise and delight at my 10 year old sons response to this question, “Hey Ben, do you mind if I take the wheels off your BMX bike and use them to make an electric powered trailer to push me to work?”

“Sure dad. But what about my bike? I really like riding it.”

“Ben, if this works I’ll buy you another bike.”

“Okay.”

5-30-07: BMX wheels mounted on trailer, a sturdy piece of plywood added to support the batteries and motor. Notice my electric motorcycle with the motor and batteries removed.

5-30-07: Motor and Batteries fit nicely in an old wine box.

6-10-07: Trailer hooked up and ready for first test run.

Notice fixed chain tensioner on wrong side of chain! Number 40 chain sprocket has same pitch as bicycle chain. So I was able to alter the sprocket in a lathe by thinning it up.

6-12-07: Floating chain idler works much better.

6-14-07: First distance run. Went to River and back (15 miles) in 17th gear on bike (20 mph?). Had over 50% of battery capacity at end of ride. Notice lid covering wine box to keep sand out of motor.

6-15-07: Rode bike to work this morning in the dark with head light and extra 10 pounds of cargo in trailer. Rode in 18th gear all the way (22-24mph). 16 miles, battery voltage at 45.1 volts at end of run (nearly empty). On way home, hit some holes in the road really hard and bent trailer frame enough for tire to rub on chain tensioner.

KEY LEARNINGS...

Safety concerns related to torque steer and lifting rear tire were not a problem in practice (at 3 Hp and less).

Hy-brid concept works great! Trailer pushes bike and synchroizes with pedaling so that rider can get as much or as little work-out as is desired.

Bike can pull trailer when batteries are dead but at less than 10mph speeds. Not ideal, but possible.

Need less weight in trailer (lower battery mass, lighter motor)

1,500-3,000 watt hub motor is recommended for next trailer build

Trailer must have stronger everything (frame, hitch and axles) and have full cover to protect from dirt and water and to improve aerodynamics.

Over 20 mph is too fast for enjoyment- Over 20mph, wind noise greatly reduces joy of ride. Need to wear a helmet to cover ears or install a fairing.

Commute time is still too long! Velocity is not enough - need more speed

Burley Aluminum Trailer is too weak (as expected) for 80 pounds of batteries and motor.

Don't use wine box as structural member (it should be veneer only)

Rear tire of bike and wheels of trailer throw a lot of dirt into trailer and gears should have fenders if to be a commuter vehicle

Pay attention to width of trailer (it must fit through a standard doorway).

Electrical quick disconnect location should be at same location as mechanical connection.

Building something half ass takes nearly as much time as buiding it well. A little extra time up front in design and during build will GREATLY improve the quality of the end product.

Trailer is potential problem in traffic. It takes extra room and automobile drivers are impatient with slow moving traffic. Cannot swerve to miss all pot holes (for all three tires) without being at risk of being clipped by a car.

Low speed commuter vehicle on road with people in cars going to and from work is not pleasant. Car drivers are very agressive and don't have patience for slow vehicles. How can this vehicle be made faster?