Run the closest gearing possible. A one tooth difference from the 19 or 20 cog to 12 cog(or smallest cog), and a 2 tooth difference above 20 cog.
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Il faut de l'audace, encore de l'audace, toujours de l'audace
1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1