Schultz Engineering Project: Electric Motorcycle Conversion

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At the 2009 AMA Vintage Days swap meet, we purchased a reproduction cafe racer style tailpiece from The HotWingGlass pieces are high quality and they have great prices.

I mounted the tail with a hinge at the front edge so I can use the hump for storage.

This tail is not just cosmetic. It helps with the aerodynamics a fair bit. I can cruise in a more upright position for the same energy I needed to crouch in without the tail. The tail gives about a 5-10% improvement in the upright riding position, but doesn't really help much in the crouched position. tail1.jpg
First of all, the dustbin fairing on my bike is VERY narrow. This caused great problems getting the front wheel to fit, but reduces the frontal area of the bike. This picture shows clearly that the dustbin is just a tad bit wider than the rear springs of the bike. An interesting web page I found today is a novel approach to solving the dustbin wheel clearance and air leakage problem:

Here is the frame work for the tail. The frame work is comprised of 4 aluminum tubes. It is simple, lightweight, stiff and strong; Buckminster Fuller would be proud.

Once, the frame work is built, putting a foam insulation skin on takes less than 1 hour. Yes, I know it's ugly and crude, but inventors must be humble while testing crazy theory's. Prove out function first, then work on cosmetics.

Quick release tail!

Each bottom tube is held in the front with one (1) ball detent quick release pin (in the vertical axis). The verticle tubes are slipped onto 2 pins (on a horizontal axis) under the hinged fiberglass tail. So, to remove the tail, just pull two pins, lift the hinged fiberglass tail and the aero tail comes off.

August 5, 2009 - No Measurable Difference

I rode 27 miles testing the tail today. The first 17 miles I rode with the full blue foam tail...After that I started cutting away portions at 2 mile intervals to see if I could improve it's performance. Pretty much, it makes no difference. It's as if it isn't there at all.

This reminds me of an important lesson I've learned over the last few years of experimenting with fairings (to see some fairings I've experimented with CLICK HERE). Pretty much anything you do with making a crude wind deflection device will not make the aerodynamics worse. The bare motorcycle and human body are evidently so aerodynamically bad, that just about anything that deflects wind around them will make energy consumption better or about the same. The main benefit of fairings, then, is that cold air, bugs, birds, stones, dust, etc. don't hit the human riding the bike which results in a more comfortable ride without wasting any additional energy.

Does this mean that crude fairings will not give me the improvement I am looking for? Perhaps. But, I know phenomenal results can be achieved without spending $10,000 making a fiberglass shell. The P-38 human powered bike is a great example. It takes 1/4 the power of my motorcycle to go 30 mph. 50% of that is probably due to rolling resistance.

September 20, 2009 Note: On review of tail, I can see that I made it way too narrow. It was not picking up the air flowing around my body and providing a clean path to recombine the air behind me (it doesn't fit my butt or kiss the back of my legs). The tail was so narrow that all the turbulent air didn't even know it was there. I need a bigger tail more like the one on Brenda Wilverts bike (getting 112 mpg) from the 1982 Craig Vetter Fuel Competition :

My first two electric riding seasons, I was riding in a nice, upright-cruising position. But, I wanted to increase my average cruise velocity and improve my range between recharges, so this season (2009) I experimented with a dustbin fairing. Just changing the handlebar and foot peg position totally changed the riding experience from one of peacefulness to one of more agreesive driving. I also lost the comfort and the great view but gained a thirst for more speed and performance. So, leaning forward was not the solution.

But, there is a fundamental problem with this seating position. It is very uncomfortable for longer rides and the view sucks! I enjoy riding a motorcycle because I like the view. I like to be IN nature; the wind in my face, breathing the air, feeling the sunlight on my body, being in the outdoors with nothing between me and the environment - a silent electric motorcycle makes this experience just that much better. Being crouched over with my belly touching the seat and my neck all kinked up barely able to see over the fairing ruins the experience.

So, I need to start over. Here is the next chapter of my Motorcycle journey; A multi-riding position design.

(Next Chapter - Building a Multi-Riding Position Motorcycle)

This webpage was written by Kraig D. Schultz. Copyright 2009-2010, Schultz Engineering, LLC