INTRODUCTION ver 1: 9199
We are supplying a set of spreadsheet tools that will give a user the ability to quantify bicycle related issues such as determining power vs speed, power to climb hills, or determining your own power capabilities, seeing the influence of CdA (aerodynamic drag), Crr (rolling resistance) and many more. We are working on a method of measuring Crr and CdA (to be posted when debugged and tested).
Each spreadsheet has been set up around a range of everyday needs to reduce user overload of superfluous amounts of information. Associated text is also included that describes each spreadsheet and refers to a set of instructional texts that suggest techniques and methods of carefully collecting the data that will be used with the spreadsheets.
Collecting data will be basically done by using your bicycle as a ergonometer and as a measuring device. Ordinarily these tests are done with an array of expensive equipment. Equipment that few of us have access to. We intend to make available test results using relatively common equipment backed by careful and specific techniques. The accuracy of the results depend on care in calibrating the measuring equipment, care in collecting data, understanding accuracy and tolerances, road selection, and finally the capability of the spreadsheets. The results may not be exact but represents useful real world conditions.
List of Spreadsheets;
FMiniUSb1.xls Full Minical US units, black and white.
FMiniUSc1.xls with color.
FMiniMc1.xls Metric Units with color.
PGDUSc1.xls Power, Gearing, Distribution, US units with color.
PGDM1.xls Not available yet.
CompUSc1.xls Comparitor, US units, with color.
CompM1.xls Not available yet
USmMus1.xls Conversion US to Metric and Metric to US units.
Coaster Not available yet
PwrCap.doc Power capability
Accel.doc Acceleration and wheel weight
When the Coaster becomes debugged associated text will be on line.
Charts and plots
Repchrt.jpg List of typical CdA, Crr
Hpcap.jpg Plot of Human Power Capability
Why these particular spreadsheet calculators were developed.
Over two years ago I was in need of a detailed analysis for a patent application for an assisted bicycle. Joel Sanders from Bell Laboratories decided to do a in-depth engineering analysis. Not knowing much about bicycle mechanics he first had to come up with the formulation which he did from first principles. Then he put this into a spreadsheet form so I could explore the variables.
It was a joy for me to have my own data and search for patterns. I could see how much power various grades required. I was able to measure my power capability. I could see exactly what the effects of adding weight did. I could see the division of power between Crr (rolling resistance) and CdA (aero drag). Acceleration was another, and even the effects of Temperature was interesting.
This gave me the ability to quantify rather than use general statements about bicycle issues so I began to think these spreadsheets would make a wonderful tool for the HPV community.
A large part of the HPV population does not have the math or engineering background so many of the Human Powered articles as an example are incomprehensible to this group. These readers are essentially excluded and fall back to using general statements to convey information. I have heard the same misconceptions and questions recycling over and over about every 12 months or so on the email lists, and in general discussions with cyclists. Some reasonably easy-to-follow tools would be a boon for any bicycle rider. However, some basic familiarity with spreadsheet operations is assumed.
The presentation of these tools is
intended to address users of both non-technical and engineering backgrounds. Joel Sanders has organized the derivations of the
formulation into a “Primer on Bicycle Mechanics, with a Spreadsheet for Power
Calculations,” available as a monograph from the HPVA. Joel felt the Primer is needed because he
found that even for those who had an in-depth engineering background they were
rusty about details and unless they took the time to carefully explore the
issues they would miss important details. The Primer is also important to
establish the "correct" formulation for the spreadsheets.
Then along came John Snyder to the spreadsheet team. He dramatically changed the look and the ease of using the spreadsheets by creating layouts, colors, and outlines so that the eye can easily separate out pertinent information. He then went on to developed a new series of spreadsheet tools using Joels formulation. Comparitors, US to Metric and Metric to US, Minical and many others.
The principal effort was on pedagogy, as you can tell, for the mechanics are available for all to investigate. Having a diverse audience and attempting to bridge across technical cultures proved difficult. The effort was on practical tool-building, and getting folks of all stripes to be more quantitative in their approach to cycling.
This effort is to be treated as an introduction to quantifying bicycle related issues. We expect changes and improvements to be made as the HPV community share techniques and as we learn more about the use of these tools. We believe that a plethora of spreadsheet applications will flow from many others, once the fundamental ideas and motivation are in place.
HAVE FUN EXPLORING
John Tetz, John Snyder, Joel Sanders