For those who like math, here's a set of formulas you can paste into an Excel spreadsheet and it will give you the most evenly-spaced cog combination.


[TABLE="width: 1000, class: grid"]
[TR]
[TD]Cassette builder[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]# cogs[/TD]
[TD][/TD]
[TD]Top[/TD]
[TD][/TD]
[TD]Bottom[/TD]
[/TR]
[TR]
[TD]5[/TD]
[TD]x[/TD]
[TD]14[/TD]
[TD]to[/TD]
[TD]28[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]ideal ratio[/TD]
[TD]=(E3/C3)^(1/(A3-1))[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]gear[/TD]
[TD]ideal[/TD]
[TD]step[/TD]
[TD]cog[/TD]
[TD]actual ratio[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]=A10+1[/TD]
[TD]=IF(A9<=$A$3,$C$3*$B$6^($A$3-A9),FALSE)[/TD]
[TD]=ROUND(B9-B8,0)[/TD]
[TD]=IF(B9=FALSE,0,C9+D8)[/TD]
[TD]=IF(B9=FALSE, "no gear",D10/D9)[/TD]
[/TR]
[TR]
[TD]=A11+1[/TD]
[TD]=IF(A10<=$A$3,$C$3*$B$6^($A$3-A10),FALSE)[/TD]
[TD]=ROUND(B10-B9,0)[/TD]
[TD]=IF(B10=FALSE,0,C10+D9)[/TD]
[TD]=IF(B10=FALSE, "no gear",D11/D10)[/TD]
[/TR]
[TR]
[TD]=A12+1[/TD]
[TD]=IF(A11<=$A$3,$C$3*$B$6^($A$3-A11),FALSE)[/TD]
[TD]=ROUND(B11-B10,0)[/TD]
[TD]=IF(B11=FALSE,0,C11+D10)[/TD]
[TD]=IF(B11=FALSE, "no gear",D12/D11)[/TD]
[/TR]
[TR]
[TD]=A13+1[/TD]
[TD]=IF(A12<=$A$3,$C$3*$B$6^($A$3-A12),FALSE)[/TD]
[TD]=ROUND(B12-B11,0)[/TD]
[TD]=IF(B12=FALSE,0,C12+D11)[/TD]
[TD]=IF(B12=FALSE, "no gear",D13/D12)[/TD]
[/TR]
[TR]
[TD]=A14+1[/TD]
[TD]=IF(A13<=$A$3,$C$3*$B$6^($A$3-A13),FALSE)[/TD]
[TD]=ROUND(B13-B12,0)[/TD]
[TD]=IF(B13=FALSE,0,C13+D12)[/TD]
[TD]=IF(B13=FALSE, "no gear",D14/D13)[/TD]
[/TR]
[TR]
[TD]=A15+1[/TD]
[TD]=IF(A14<=$A$3,$C$3*$B$6^($A$3-A14),FALSE)[/TD]
[TD]=ROUND(B14-B13,0)[/TD]
[TD]=IF(B14=FALSE,0,C14+D13)[/TD]
[TD]=IF(B14=FALSE, "no gear",D15/D14)[/TD]
[/TR]
[TR]
[TD]=A16+1[/TD]
[TD]=IF(A15<=$A$3,$C$3*$B$6^($A$3-A15),FALSE)[/TD]
[TD]=ROUND(B15-B14,0)[/TD]
[TD]=IF(B15=FALSE,0,C15+D14)[/TD]
[TD]=IF(B15=FALSE, "no gear",D16/D15)[/TD]
[/TR]
[TR]
[TD]=A17+1[/TD]
[TD]=IF(A16<=$A$3,$C$3*$B$6^($A$3-A16),FALSE)[/TD]
[TD]=ROUND(B16-B15,0)[/TD]
[TD]=IF(B16=FALSE,0,C16+D15)[/TD]
[TD]=IF(B16=FALSE, "no gear",D17/D16)[/TD]
[/TR]
[TR]
[TD]=A18+1[/TD]
[TD]=IF(A17<=$A$3,$C$3*$B$6^($A$3-A17),FALSE)[/TD]
[TD]=ROUND(B17-B16,0)[/TD]
[TD]=IF(B17=FALSE,0,C17+D16)[/TD]
[TD]=IF(B17=FALSE, "no gear",D18/D17)[/TD]
[/TR]
[TR]
[TD]=A19+1[/TD]
[TD]=IF(A18<=$A$3,$C$3*$B$6^($A$3-A18),FALSE)[/TD]
[TD]=ROUND(B18-B17,0)[/TD]
[TD]=IF(B18=FALSE,0,C18+D17)[/TD]
[TD]=IF(B18=FALSE, "no gear",D19/D18)[/TD]
[/TR]
[TR]
[TD]1[/TD]
[TD]=IF(A19<=$A$3,$C$3*$B$6^($A$3-A19),FALSE)[/TD]
[TD]=ROUND(B19-B18,0)[/TD]
[TD]=IF(B19=FALSE,0,C19+D18)[/TD]
[TD][/TD]
[/TR]
[/TABLE]