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Hub gear ratio spreadsheet

06/03/2010

John S Allen is one of the greatest technical writers about bicycle technology. He has recently produced an amazing spreadsheet of hub gear ratios, calculated from first principles. This reveals that, in some cases, the ratios quoted by the manufacturers are incorrect.

John says,

‘I felt the exercise to be useful because almost all the information I’ve seen about ratios gives decimal numbers. The actual ratios are fractions, many of which do not reduce exactly to decimals. Some numbers are given to only two places after the decimal point, not really as accurate as would be desirable. I also found incorrect rounding and in some materials I reviewed, transcription errors.’

Here’s a link to this uniquely useful spreadsheet.

Tony

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From → Gears

4 Comments
  1. Hi Tony,

    It is much work to, so I have done it. I hope the English can accept the fact that the decimal “.” is a “,” in continental spreadsheets.
    http://www.velofilie.nl/_fpclass/gearratioenglish.xlsx

    • Fantastic work, Wiel – many thanks. I’m sure a lot of people will find this useful, especially being able easily to compare so many different gearing systems. By the way, the decimal points appear as Anglo-Saxon style dots on my spreadsheet, rather than commas, so Excel apparently knows to change the format if the preferences are set for UK or other Anglophone use.
      Cheers,
      Tony

  2. Hello Tony,

    I have recently made an Excelsheet for gearing choises. There is a metric- and an inch-chart.
    http://www.velofilie.nl/_fpclass/gearchartenglishmetric.xls http://www.velofilie.nl/_fpclass/gearchartenglishinches.xls

    It may be usefull to somebody………

    Regards, Wiel van den Broek

    • Hi Wiel,
      Hartelijk bedankt – good stuff! There’s a lot of work gone into making these useful spreadsheets. However, for the results to express the gears correctly in the Anglo-Saxon inches system, all the results in the inches version of the spreadsheet need to be divided by pi (i.e. 22/7). This is because gears expressed in inches represent the diameter of a direct drive wheel (as on an Ordinary, High Bicycle of so-called Penny Farthing) rather than the distance travelled per pedal rotation (i.e. the development). Would you be able to modify the spreadsheet in that way? If so, that would make it very useful.
      Cheers,
      Tony

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