the 6 I get using 13t/ 16t [1,2,3 ..]

[TABLE]
[TR]
[TD][TABLE]
[TR]
[TH]30.8[/TH]
[/TR]
[TR]
[TH]25.0[/TH]
[/TR]
[/TABLE]
[/TD]
[TD][TABLE]
[TR]
[TH]48.2[/TH]
[/TR]
[TR]
[TH]39.2[/TH]
[/TR]
[/TABLE]
[/TD]
[TD][TABLE]
[TR]
[TH]75.6[/TH]
[/TR]
[TR]
[TH]61.4

[/TH]
[/TR]
[/TABLE]
[/TD]
[/TR]
[/TABLE]




You missed the OP saying they substituted a 39t , perhaps? a non standard Brommy chainring
the new B spider crank allows any 130 BCD chainring to be used. they got an Ultegra one.