Hi team! Very cool Shimano Arabesque derailleur set! 28.6 clamp...bottom swing top pull front derailleur with the matching rear derailleur for double. Fairly certain these will work best with friction shifters. I love the Dia-Compe ENE shifters and the Rivendell Silvers shifters...they very much breath new life into new and old drivetrains alike! You can blame me if you find you forgo index shifting all together there after! I've got the matching crankset listed in a separate auction. I can work with you on combined shipping if you need both the derailleurs and crankset!