The Search for Fuel Economy

Pages from a Designers' Notebook

Sep 25, 2008

Chap. 18: Where should the nose weight be? How much?
Well, we are not quite finished with the weight. After riding this thing for a while, I realized that there might be a difference between having the weight low - or the weight high. I decided to build a structure at the nose that would allow me to add or subtract weights - and move them up or down.
5 pound divers' weights
10 pounds installed
When I removed the original bar bell weight and lead balls, I weighed them. Instead of 25 pounds, they added up to only 20 pounds. Never the less, they felt too heavy. This was not because they collapsed the front end. The front suspension handled the weight just fine....

They just "Felt" heavy.

I found 5 pound lead weights at a local dive shop and put 10 pounds at the top and10 at the bottom.

Riding with 20 pounds of lead
U-turns were hard to do with 20 pounds. One nice thing: I did not have to put my feet down at stop signs. The streamliner wanted to balance upright, by itself.

I began to realize that the weights tended to do what I thought they would do. I began to distrust the way I was doing things. It was time for a double blind test.

Double blind test
We rode down to Big Sur and found a very windy pass where the air whipped back and forth. It was a very scarey place to ride but a perfect place to test.

Son, Zak randomly arranged the weights while I averted my eyes. After each pass, I wrote down my impressesions... how it felt in the wind and other observations. I also noted where I thought the weights might be bolted on. It was soon clear that four weights were too much so we reduced the tests to three weights, or 15 pounds.

I was surprized at how hard it was to do a double blind test. Right away, I could tell when the weights were high because it was harder to get off the side stand and harder to turn onto the road.

Weights at the bottom made the bike feel much lighter. U-turns had a normal feeling and still seemed to defeat the winds fine.

Other than that, any combination of three weights seemed to do defeat side winds the same. The logical conclusion, then was to put all three at the bottom, which was convenient.

Weight at bottom just "feels better."

I should have known that weight at the front was good for stability.

We feel the stability everytime we load a big bag of dog food at the front of our shopping cart. A cart loaded like this is very hard to turn and wants to go straight.

Three, 5 pound lead diver's weights fit neatly in behind the nose cap. I suspect that 10 pounds will do the job. I will ride with this for a while and after I get used to three weights, I will remove the bottom one and see how it feels.
Now it is time to return to finishing up the streamlining...

Master Index to the Last Vetter Fairing Story

Page posted Sep 25, 2008