Joined: Jan 2009
Posts: 43,974
Likes: 6,154
From: New York, NY, and High Falls, NY, USA
Bikes: 1962 Rudge Sports, 1971 Raleigh Super Course, 1971 Raleigh Pro Track, 1974 Raleigh International, 1975 Viscount Fixie, 1982 McLean, 1996 Lemond (Ti), 2002 Burley Zydeco tandem
Crank size doesn't figure into it. But I realize just now that I might be wrong. Your existing derailleur may require the cable housing to enter it. If the replacement requires a bare cable, then you'll need a different sort of cable guide.