Pretty in Pink, dunno why
Join Date: Feb 2009
Location: Redondo Beach
Bike Gearing Calculator (Excel File)
I built this Excel file a while ago. Here's what it does:
This table shows the sprocket ratios for the various front and rear sprocket combinations.
Cell D14 is going to tell you what the change in gearing is going to be. A negative number means your gearing is going to be lower;
a positive number means the gearing will be higher
Effect on Chain Length Adjustment
This table will tell you how much you are going to have to move the axle to maintain the chain slack you had prior to changing the
gearing. A negative number means you will be moving the axle backwards, a positive number means the axle moves forward. The
shaded areas indicate what is likely to be possible without adding (or removing) links to the chain.
Indicated Speed Change
Based on the gearing you selected, this is what you can expect to see as indicated speed in 5th gear.
Actual Speed Change
Based on the gearing you selected, this is what you can expect the actual speed to be in 5th gear. The spreadsheet is using the
average of you observed actual speeds to derive the actual speed shown in the table.
RPM at Speed – Revised Gearing, Actual Speed
This table shows the calculated actual speeds you should see with your revised gearing. This table is useful for checking to see if
your revised gearing will have you at comfortable RPM at common speed limits, and for comparing to the stock gearing table below.
A table of corrected speedometer readings.
Since we can't upload Excel files, I had to attach it as a .zip file. It should self-extract when you download it.
Tom [email protected]
“I decided I could lose nothing by the soft approach. If that didn't produce for me—and I didn't think it would—nature could take its course and we could bust up the furniture.”
'How' are words so important they cannot be too often used.”
Sting like a butterfly.
Noli Timere Messorem
Last edited by Tom Schmitz; 07-23-2013 at 05:27 PM.