UNO´s rear derailleur puts shifting technology where it makes the most sense: in the derailleur, where the shifting action happens. Command it to upshift by pushing the lever to transmit hydraulic fluid and UNO´s rear derailleur responds by precisely upshifting from 1-4 gears based on your preferred setting. Downshift and UNO´s secure shifting instantly puts you in the gear you want without unintended downshifting. You can also adjust your UNO derailleur to your desired cog size and fine tune your gear selection.