This program no longer being developed
Please give the new version a try.
Please send comments to:
Mike Sherman at
wheelwrightmike@gmail.com
| Inputs | ||
| Cassette | Select the Rear sprockets, either from a preset on the pull-down menu, or by editing the
individual sprockets with +/- buttons. The X button removes the sprocket. |
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| Chainrings | Select the Chainrings by editing the individual sprockets with +/- buttons. The X button removes the sprocket. | |
| Wheel | Select a wheel and tire size from the pull down menu.
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| Crank | Select a crank arm length from the pull down menu. This value is only used for Sheldon Brown's Gain Ratio Table. |
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| Outputs | ||
| Gear Inch Chart | This is the traditional Gear Inch Chart. The values are the equivalent diameter of a direct drive wheel. Sheldon Brown has a good description on his |
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| Semi-Log Graph | This is my personal favorite.
The log graph can give you a pretty good idea of what a set of gears will feel like.
Evenly spaced gears on
this graph will feel evenly spaced to your legs.
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| Gain Ratio Table | The Link explains it better than I can.
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| Rollout Table | This table show how far the bike moves with each revolution of the pedals. It is usually expressed in meters. I provide English or Metric units. This measurement is also know as development |
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| Speed over RPM Range | The title pretty much explains it. You can set the upper and lower limits of your cadance.
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| Speed table | Shows you speed at the selected crank RPM.
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| Save/Recall/Swap Buttons | This is intended to help you compair two gearing configurations. The Save button saves the current selections to a cookie on your system. The Recall button will recall the saved selections. It does not save the current selections first. The Swap button swaps the current selections with the last saved selections. The current selections are saved. |
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| Bookmark | I thought it would be great to be able be able to bookmark a complete set of gears. Unfortuneatly,
some browsers don't allow you to make a bookmark from javascript. I can see why they did that. On some browsers, the bookmark button will re-load the page with all of the settings imbeded in the URL and puts up a pop-up to tell you what it did. You can then bookmark the page the normal way to save a gear set. |
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| Highlighting | While the mouse is any of the cog change buttons, the element changing it will effect is highlighted on
the gear table, the log graph, and the speed graph. It does force more redrawing of the effected tables A checkbox at the bottom enables this. |
| Notes about Gearing |
There are lots of ways to look at bicycle gearing. There are many people with strong opinions about how bicycle gearing should be set up. I have my own opinions. I have tried not to allow them to influence the calculator too much, but some has crept in. A user pointed this out to me with the way the sorting works on the speed range graph. I suggest you look at Sheldon Brown's article Gear Theory for Bicyclists (edited by John Allen). If you're interested in half-step gearing you might want to look at Appleblock web tools half-step gearing designer. |
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This program began it's life for me as a fortran program I wrote in about 1975.
It has evolved and morphed over the years to Basic, C, perl/cgi, and Javascript versions. Major influences over the years have been a BASIC program written in 1978 by my friend Richard Curtiss of Seattle, and a C program posted on 17 Aug 1994 23:21:36 GMT on rec.bicycles.tech by speed@etecnw.com (Paul W. Laudon x7241 (sun)). The program is now a client side javascript program. It was developed in 2004 because I lost my access to a server to run the perl/cgi program. That loss turned out to be a good thing. This javascript version has evolved quite a bit with the addition of real graphics and is proving to be quite popular. Thanks to JimG for the derailleur capacity code. Thanks to Sheldon Brown for wheel diameter data and his gain ratio display method. Thanks to www.walterzorn.com for the DHTML JavaScript VectorGraphics Library (seems to have been hijacked link farm) And thanks very much to the many users who have made suggestions and reported bugs. |
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The major new feature of v4.2 is the ability to call the page with a gear configuration
in the URL. This, combined with a bookmark button will allow the user to bookmark the
page with all the parameters they had selected and recall the complete selection later.
It will also allow other web pages to open the calculator with a specific configuration. |
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Programming notes
Append the parameters to the url by adding a question mark (?) followed by the program parameters you want in the format NAME=VALUE. NAME=VALUE pairs must be separated by a "&" character. Only the sprockets listed in the URL will be displayed Any values, other than sprockets, not included in the URL will be set to the default values. Any spaces in the TITLE should be replaced with %20. |
https://mike-sherman.github.io/shift_v4/index.html?R0=30&R1=40&R2=50&C0=13&C1=15&C2=18&C3=21&C4=25&C5=30&CR=180&TITLE=Loaded%20from%20URL
| Argument NAME |
Description |
Value |
| "R0" |
Smallest or Single Chainring |
integer |
| "R1" |
Middle or Largest Chainring |
integer |
| "R2" |
Largest Chaingring (if there are 3) |
integer |
| "C0" |
Smallest Cassette or Freewheel Cog |
integer |
| "C1" |
Second Smallest Cog |
integer |
| "C2" - "C9" |
Freewheel or Cassette Cogs |
integer |
| "C10" |
Largest Cassette Cog on an 11 speed |
integer |
| "CAS" |
Index of selected Cassette |
integer |
| "WI" |
Wheel Index sorry, this is messy |
integer |
| "CR" |
Crank Arm Length in mm |
integer |
| "RT" |
Rollout Display type 0 = Meters, 1 = inches ???? |
integer |
| "ST" |
Speed Display type (0/1) |
integer |
| "RPM" |
RPM for "Speed at" table |
integer |
| "SRT" |
Units for "Speed at" table |
integer |
| "lRPM" |
Low RPM for Speed over RPM range display |
integer |
| "hRMP" |
High RPM for Speed over RPM range display |
integer |
| "G" |
Grid on/off for Speed over RPM range display ("show"/"hide") |
string |
| "S" |
Sort on/off for Speed over RPM range display ("yes"/"no") |
string |
| "HL" |
Enable mouseover highlighting 1=ON / 0=OFF |
integer |
| "TITLE" |
Page Title Spaces must be replaced with "%20" |
string |
| 08/04/2004 | created
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| 08/11/2004 | Added Cookies with save/recall/swap Fixed direct data entry bug with < max # cogs or rings |
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Version 2.0 |
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| 07/13/2005 - 03/08/2007 | Derailleur capacity added by Jim G Added 650B wheel sizes Change some input areas to text areas (looks nicer) gearTableLabel (rearcap, frontcap) Added speed table |
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Version 3.0 |
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| 04/15/2009 - 04/18/2009 | Graphical log plot with Walter Zorn's DHTML JavaScript
VectorGraphics Library 11 speed support, Campy 11 speed cassettes Added DuraAce 10 speed cassettes Center the ascii tables when not 11 speed Fixed bug in new centering - with 1 or 2 rings |
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Version 3.1 |
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| 04/19/2009 - 05/05/2009 | Split the original file up into 3 pieces Put text areas inside div's so one html file can support both ASCII and vector graphic displays. Change graph fonts to blue. Added 29er wheels 1.95, 2.1, 2.2, more tubular widths All tables drawn with vector graphics library Some code cleanup, output functions last Added error checking logic when incrementing/decrementing cog values Added sachs 13-28, 6 sp and 13-32, 7 sp |
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Version 3.2 |
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| 07/21/2009 | check the RolloutType and SpeedType each time you draw the tables fixes a bug where display and radio buttons don't agree after a reload |
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Version 3.3 |
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| 10/24/2009 - 01/07/2010 | Added zinn crank lengths request from Greg M 130, 135, 140, 145, 150, 155, 160 and 190, 195, 200, 205, 210, 215, 220 Add 700x23 wheel size per user request |
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Version 4.0 |
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| 02/01/2010 - 02/06/2010 | Add rpm/speed range display Fixed ghosted gear number labels on the top gear table Auto scale the rpm/speed range table Add some error handling on rpm range values Switchable horizontal lines in rpm/speed range table Fix errors in cassette numbering Add labels to sorted and unsorted speed range displays Sorted rpm/speed range display |
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Version 4.1 |
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| 02/08/2010 - 03/24/2010 | Resize canvas for rpm/speed Add rpm range to cookie/save/load Add spacing between label and rpm range chart Make all color selections in the graphics functions variables. - there was a private release of the code up to this point Add zero checking to readRings() and readCogs() for when users enter |
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Version 4.2 |
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| 11/17/2010 - 1/1/2011 | Fix display 3.00 value on gain ratio tables Fix bug displaying rollout > 10 meters Add ability to read parameters from URL Add credits page (this page) Add setCrank() function Add bookmark buttons - w & w/o the data Add bookmark/url info to credits page Add revision history to credits page. Add IRD freewheels to selectCassette.js Fix bug when typing in cogs or rings Add same fix to a few other inputs Fix typo on main page - Graphical |
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Version 4.3 |
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| 02/23/2011 - 04/17/2011 | Add 20x1.5 wheel size to javascript (36) 40-406 tire (20") change bookmark to go to index.html directly Add SRAM X5 cassette to selectCassette.js & index.html (11-34, 9-speed) Clean up my internal documentation a bit. load with recall and swap - always comes back sorted sortgears is not and int - not read properly from cookie (as was showgrid) sortgears = "yes" | "no" some places it was "on" | "off" split shift.js (this file) into a bunch of smaller files for easier management selectCassette.js renamed to shiftCassettes.js recall fixed. was reading 'sort' and 'grid' from cookie w parse()= WRONG! tighten up the display a bit (index.html) tighten up the display a bit more (index.html) fix problem with testing if there is a cookie - swap/recall problems fix a bunch of html issues (thanks to chrome) update the links to the sources, moved to credits page |
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Version 4.3.1 |
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| 04/09/2011 - 05/19/2011 | Move some functions around again. Bug fix - add update to setRPM - now display will update Bookmark set now reopens link with the arguments and posts an alert to save w Ctrl-D Speed up bookmark load - was updating screen too often Remove bookmark button (not the bookmarkSet button) Work on bookmarkSet Change default upper rpm to 100 (speed/rpm graph) Fixed problems with setting rpms on speed/rpm graph fixed parseInt problem. Same parseInt problem fixed in other areas of the code Add 700x30 wheel size Add selectedCassette() to the URL save Add code to select the correct items in the pull down menus when loaded from URL. Now all picklists update from bookmarks Changed the names of the functions from 'write' to 'update' Add a small help section to this page Move the speed table to the bottom Fix so Check boxes get updated reading bookmarks |
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Version 4.4 |
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| 05/20/2011 - 05/26/2011 | Updates to this page. Add Help button on calculator page. Move bookmark button above the chart type selection Add highlight to gear table gear on hover over cog control buttons Add highlight to log and speed graphs Add checkbox to enable/disable highlighting Add highlighting to cog text boxes Editing a cog directly removes selected cassette |
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Version 4.4.1 |
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| 06/06/2011 - 06/07/2011 | Remove border from Derailer Capacity display and link to Sheldon. Make all href's open on new page/tab Do some formatting cleanup. |
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Version 4.4.2 |
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| 06/13/2011 - 07/01/2011 | Code cleanup - standardize display I/O function names. Add URL text box to main page. Fix save/swap/recall with Chrome. Tested w FF4, FF5, Chrome, and IE7. |
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A more detailed change log can be found at the top of shift.js.
Return to This version of the Gear Calculator
Return to The new version of my Gear Calculator
Return to My bike page
Return to My main page