sensah empire pro carbon fiber 1x12/2x12 speed road bike shifter cassettes bicycle derailleur groupset (212(carbon fibre)+28t+ybn(12s)) sensah the mechanism is similar to 'double tap' from another brand, but the shifters aren't identical to those---there aren't multiple lever paddles, there is elegantly only the one lever that operates the brake, and in the manner described ahead, also operates the shifting. actually nice to use. -on the right/rear lever, to shift to low (easier) gear, you give a strong push of the entire brake lever inward, that is, toward the centerline of bike. to shift back toward a higher (harder) gear, you press