Chain rings and derailleur compatibility

[ddallam]

I have a vintage steel bike with 53/42 and a Super Record rear derailleur, all mid-80's era. Does anyone know if that derailleur will allow me to drop the front to 53/39? Will the derailleur take up the extra slack from the loss of the three teeth up front and the 14 teeth difference in chain rings?

 

[boudreaux]

I have a vintage steel bike with 53/42 and a Super Record rear derailleur, all mid-80's era. Does anyone know if that derailleur will allow me to drop the front to 53/39? Will the derailleur take up the extra slack from the loss of the three teeth up front and the 14 teeth difference in chain rings?

Most likely, but one hedge is just stay out of the small/small.