microSHIFT Acolyte RD-M5185M-B SpringLock Rear Derailleur - 8 Speed, Medium Cage, Black, SpringLock Chain Retention RD0178

The heart of this microSHIFT Acolyte derailleur is the innovative SpringLock system. By pairing a customized linear rate high tension spring and a dual stage activation mechanism, we’ve developed a system that can provide substantial chain security when you need it and can be turned off when you don’t.  To engage the clutch, turn the engagement bolt clockwise until it clicks. There’s no way to overtighten the bolt. To disengage the clutch for wheel removal, flip the switch. It’s that simple.