When I had downtube shifters, the friction had to be adjusted really tight (and often) or the bike would shift up or start clacking occasionally when I was out of the saddle. I've never had that problem with STI.
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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