larger front chainring, smaller low cog, pedal faster. my top is 45.3 in 53,12. search this topic and you will find numerous threads asking for top speeds. I think the max was over 60.
__________________
2010 Kestrel RT900SL, 800k carbon, chorus/record, speedplay, zonda
2000 litespeed Unicoi Ti, XTR,XT, Campy crank, time atac, carbon forks